Gilbert Davey's forgotten pre-war writing
for Practical Wireless and other journals. Pre-War Writing
I have had a long-term aim to find out about Gilbert Davey’s pre-war radio writing, and to add details to this site.   A document found by his daughter among his Army records has now given me a huge head-start in opening up this aspect of his work.   With the help of PW Publishing Ltd, current publishers of Practical Wireless, a selection of Davey's pre-war articles is available for download from this page.


Welcome and introduction,
contact details, disclaimer,
rights notice, BVWS link,
site map.
The man who introduced radio
construction to several generations
of boys, many of whom became radio
or communications professionals.
The history of the famous
one-valve circuit, 1948-78.
The Studio 'E' 1-valver and
the Focus Transistor radio:
downloads for these famous
designs, and lots more!
A growing resource for those who
built Davey designs years ago, or who
simply wish to know more about them.
(This page)
Davey's forgotten pre-war writing for
Practical Wireless and other journals.
Downloads for seven pre-war articles.
The Boy's Own Paper - a
complete listing of Davey's
designs and articles.
Davey's articles in the
compendium books produced 
by BOP's Editor, Jack Cox.
Davey's most well-known book,
which ran to six editions.
The other titles introduced young constructors to
every aspect of the radio and electronics hobby.
Davey sets built by contributors -
including designs that could have been
lost but for some prolonged detective work.
Two home-made coils to use in place of the all-too-scarce
commercial types, suppliers for other components, and
other sources of useful information.
Latest news, links to other sites of interest,
and news archive.
Hover your mouse over the
navigation buttons above for
brief page contents.
Pages marked  >  give access to
one or more subsidiary pages -
see also Site Map at bottom
of WELCOME page.


DOWN TO
PRE-WAR ARTICLE DOWNLOADS
The list is not necessarily exhaustive.
    Gilbert Davey's list of pre-war articles, probably typed during enlistment in the Royal Signals.

    Image courtesy Claire Davey; reproduced by kind permission.

The key document is a list of 31 articles written during 1933-35, plus another article dated June 1941, for Practical Wireless and other journals. Davey probably typed this up himself as part of the formalities in enlisting with the Royal Corps of Signals.

The list is not exhaustive.   Davey himself stated that he was writing freelance articles by the age of 16 (1929), so there are some earlier articles to be sought.   Two Practical Wireless articles have so far been found that Davey did not list: one in 1932, and one in 1934.

There is seemingly an error in Davey's listing of the last three articles, dated 1935.   These dates were Wednesdays in 1935, but Practical Wireless was dated every Saturday.   So far, every weekly edition of PW has been searched for the years 1932-35, 1937 - when the dates in question did all fall on Saturday - and 1941, but these three articles have not yet been traced.

For convenience, I have included in this "Pre-War" section the one wartime article found so far.   Given that Davey spent the war in Europe on his clandestine work, it seems unlikely that many further wartime articles of his will be found.

Much thus remains to be done: completion of the trawl through Practical Wireless for the pre-war years, and a search for material published in any other journal from about 1929 to World War 2.   For the time being, therefore, this page must be regarded as very much a first reconnoitre!

Leafing through the "wireless" magazines of this period, one is immediately caught up in the excitement of those times, when radio was still regarded by some as a near-miracle.   The popularity of radio construction as a hobby, not only for its own sake but for many as a means of acquiring a radio set cheaply, is attested by the sheer number of magazine titles (see below).   The wireless set was morphing, from a laboratory-style instrument grudgingly given space in the corner of the living-room, into an imposing item of fashionable furniture.   Technical innovations came thick and fast.   For commercially made receivers, superhets were rapidly supplanting "straight" sets.   Real improvements in reproduction came with negative feedback and vastly better loudspeakers.   And Baird's experimental transmissions marked the birth-pangs of television . . .

Gaining access to these magazines at the British Library is cuurently a little less straightforward for me (living near London) than previously.   The outdated Newspaper Library at Colindale (north-west London) has been closed, and most newspapers and periodicals have been moved to a new environment-controlled facility at Boston Spa, West Yorkshire.   All this material is to be digitised over the coming years for eventual instant on-line access.   Meanwhile, yet-to-be-digitised materials - including pre-war radio journals - have to be transported to the St Pancras site on request, with a 48-hour waiting time.

The next difficulty is the frequent title changes among the many pre-war radio journals, usually marking one title's absorption of another, or a split from one title into two.   These changes are faithfully recorded (most of the time) by the British Library's catalogue, but are confusing for the researcher.   Entering "Practical Wireless" in the catalogue's search facility, for example, yields nothing before 1950 (see below).

Finally, the magazines themselves present some further hindrances.   Contents lists are either basic (e.g. "On Other Pages"), or completely lacking.   Some magazines produced indexes, which are often found bound in with the magazines that the British Library holds, but article titles only are mostly given.   Authors were anyway often either uncredited or hidden behind pen-names such as "Detector", "A Radio Engineer", or "T Onearm" (he reviewed records, of course).

Many of the Practical Wireless articles on Davey's list are indeed not credited to him, and are annotated as such in the entries below.   Whatever the reasons for this practice, it probably means that Davey (despite his considerable output) became less well-known before the war than he might, and certainly does a real dis-service to the future researcher.   When I come to extend my search beyond his list, the only proper course will be to exclude anything that was not credited to him unless I can point to overwhelming evidence of his authorship.

When I move on to look for other Davey articles to fill in the gaps mentioned above, I will be faced with the sheer number of magazine titles produced between the mid-1920s and mid-1930s.   Searching just for journals whose titles included the word "Wireless", one finds no less than 14 at the peak of the wireless frenzy during 1925, settling to 8 or 10 during 1928-1934.

In the entries for these articles, I have given a little more detail about the content of each than for the post-war work listed on other pages within this section.   This seems justified for the light these early articles throw upon the range of Davey's interests and knowledge in the period around his twentieth year.   As will be seen, only a minority of the articles on Davey's list describe fully worked-up designs; others give basic information for experienced constructors.   The rest are hints, tips and experiment ideas; the great majority of these (over twenty) are for the short-wave listener.   Most articles give basic component information, but valves are rarely specified beyond type (e.g. RF pentode, triode, etc).

The entry for each article available as a PDF download (bottom of this page) carries a note indicating this.

The following paragraphs give brief historical notes about each periodical.   In view of the possibility that those interested may resort to the British Library to access them (it is necessary to register as a Reader), basic catalogue information is given at the head of the list of articles for each journal.   Use the links below to get quickly down to the detailed article lists.

Modern Wireless
Published monthly during 1923-33 by Amalgamated Press, Modern Wireless was then absorbed by its sister journal Popular Wireless.   Nicely produced, it used many re-touched photographs as well as line illustrations.

Armchair Science
Published monthly during 1929-41 by Wyman & Sons Ltd, the journal carried articles on contemporary science and technology appealing to the teenager and adult, with numerous photographs and futuristic illustrations.

Popular Wireless
This journal passed through several incarnations: as Popular Wireless Weekly (1922-24), Popular Wireless and Wireless Review (1924-26), Popular Wireless (1926-34), and Popular Wireless and Television Times (1934-37) - this latter title contains the article listed by Davey.   It was published by Amalgamated Press Ltd, and shared an editorial team with Wireless Constructor.   Subjects covered a wide range, including constructional articles, short-wave topics, news on broadcasting, technical notes, and television developments.   Sir Oliver Lodge and P P Eckersley are listed as Scientific Advisor and Chief Radio Consultant respectively.

Practical Wireless
Editied by the formidable F J Camm for its first 26 years, Practical Wireless was perhaps the flagship of the "Practical" titles published by George Newnes Ltd and affectionately known as "Camm's Comics".   It began in September 1932 as a supplement to Hobbies, which was renamed temporarily as Hobbies and Wireless Supplement.   In 1933, the two titles split to become Hobbies (later Hobbies Weekly) and Practical Wireless, which itself later spawned a companion title Practical Television.   The unapproachable standard of its illustrations, drawn either by Camm himself or by members of his artistic "school", is well-known; many of them are instantly recognisable as they also appeared in the Wireless Constructor's Encyclopaedia or Everyman's Wireless Book.

Before using the list, please read the caution and usage notes on this section's introductory page.

  Modern Wireless, Amalgamated Press Ltd.
BL shelfmark: (P) RT 40-E(42).   Serial holdings are not recorded; the year and date must be specified.   Monthly editions are bound by calendar year.

Edition:   Article: Construction and key components, or description:
Coils: A = aerial winding;
          MW = medium wave winding;
          LW = long wave winding;
          SW = short wave winding;
          R = reaction or reflex winding

Page:
No 83, Vol 20
1933 November
  Curing Hum in A.C. Sets -












Lead-covered house-wiring cable suggested for heater wiring,
     with sheath earthed, as alternative to twisted flex.
Short connections from grid components to grid terminals.
Electrolytic capacitors across auto-bias cathode resistors -
     this seemingly not standard practice then.
Adequate decoupling of anode circuits, especially at detector.
Output filter capacitor also serves to isolate speaker from HT.
Chokes and transformers placed at right-angles, and no more
     than one trannsformer coupling between stages.
Pair of HF suppression capacitors across mains, centre point
     earthed.
Value of good earth connection in avoiding hum.
397













  Armchair Science, Wyman & Sons Ltd.
BL shelfmark: P.P.1447.bac.   Serial holdings are not recorded; the year and date must be specified.   Monthly editions are bound by publisher's volumes, running from April to March.

Edition:   Article: Construction and key components or description:
Coils: A = aerial winding;
          MW = medium wave winding;
          LW = long wave winding;
          SW = short wave winding;
          R = reaction or reflex winding

Page:
No 10, Vol 5
1934 January
  Wireless in Every Room -



Simple scheme for feeding speaker signals to points
     around the house.   Runs of twin DCC wire connect
     speakers in series, with shorting switches.
637




  Popular Wireless and Television Times, Amalgamated Press Ltd.
Weekly editions are bound into two books per calendar year (each year with its own shelfmark).

Edition:   Article: Construction and key components, or description:
Coils: A = aerial winding;
          MW = medium wave winding;
          LW = long wave winding;
          SW = short wave winding;
          R = reaction or reflex winding

Page:
No 634, Vol 25
1934, 28 July
  Some Famous Circuits of the Past -

Strapline reads:
     "It is always interesting and enlightening to
     look back over past events, and in radio this
     process is particularly fascinating, as is
     shown in this article".

     Davey wrote a similar article, entitled
     "Experimental Circuits", covering much the
     same ground, which was published in the
     June 1941 edition of Practical Wireless
     (see below).







Some obsolete circuits recalled that must have looked odd
to readers of 1934 (and look quite outlandish to the modern eye),
but which Davey thought might serve for new experiments with
improved valves.   These included:
DeForest Ultra-audion: leaky-grid detection; grid signal fed from
     junction of series-connected coil and tuning capacitor.
     Filament rheostat as reaction control.
Gernsback Monodyne: HT+ve connected to earth, and to aerial
     via an aperiodic coil.   Most of circuit thus negative
     with respect to earth; grid leak ran to HT/earth line.
     Davey could not personally confirm performance of this circuit!
Armstrong and Flewellyn regenerative circuits.
Simple Super: leaky-grid detection, with coil between grid
     capacitor and grid, coupled to coil in anode circuit.
Filadyne: an attempt to feed aerial input to filament circuit.
     Filament current flows through two coils, one of
     which is tuning coil, tapped for aerial connection.
     HT+ve led to grid, via phones and a third coil.
     Anode connected to slider of potentiometer across LT supply.
499




















  Practical Wireless, George Newnes Ltd.
Pre-war editions are catalogued by the British Library as "Practical wireless and practical television".   Weekly editions are bound into two books per calendar year (each year with its own shelfmark), but publisher's volumes run from September to March, and March to September.   This means that each bound volume carries parts of two publisher's volumes.

Edition:   Article: Construction and key components, or description:
Coils: A = aerial winding;
          MW = medium wave winding;
          LW = long wave winding;
          SW = short wave winding;
          R = reaction or reflex winding

Page:
No 7, Vol 1
1932, 5 November
  Causes of Instability (not on Davey's list) -







Suggested cures for old sets with inadequate decoupling, which
often became unstable when fitted with more efficient valves:
Output filter: LF choke in anode circuit (c 20H), and 2μF
     capacitor from anode to speaker terminal.
Anti motor-boating circuit: 25kΩ resistor in HT supply to
     detector, and 22μF capacitor from anode side of resistor
     to ground (i.e. RC decoupling).
334







No 46, Vol 2
1933, 5 August
  Causes of "Rattle" -












Mechanical troubles in speaker or cabinet to be ruled out first,
then these strategies suggested:
Output valve overloaded: check grid bias voltage and
     anode current.
Check readings on preceding valves also.
Screen-grid RF stage overload: variable capacitor in aerial
     lead, or try substituting variable-mu valve.
Power-grid detection: substitute higher value grid leak, and
     increase anode voltage.
Less common troubles include loose covers of chokes or
     transformers, faulty grid-leak resistors, run-down
     or faulty batteries, especially grid-bias batteries.
639












No 58, Vol 3
1933, 28 October
  Make Your Set Selective -














Suggestions for improving listening spoiled by poor
selectivity, especially after dark:
Shortened aerial, if desired stations received at
     good strength, or aerial trimmer, ideally as
     variable control on panel.
"X" coil (aerial tapping towards earth end?) in place of
     centre-tapped tuning coil, or find optimum tapping point
     in existing coil by trial and error with needle through
     double-cotton insulation.
Aperiodic coil: new separate coil, or form new aperiodic
     winding, either as layer on top of solenoid-type coil,
     or as hank-wound coil tied beside annular coil.
Band-pass tuning best done by wholesale modification to
     tuning circuits.
303














No 67, Vol 3
1933, 30 December
  Preventing HF Leakage -











Symptoms of stray HF listed, including instability, overloading,
harsh or sibilant tone.   Cures suggested include:
HF choke in detector anode circuit, and bypass capacitor
     from anode to ground.
Arrangement as above, with additional bypass capacitor
     from HT side of choke to ground.
Stopper resistor at grid of AF stage.
For short-wave sets, hand- and body-capacitance effects
     minimised with bypass capacitor from output valve
     anode to ground, with possibly HF chokes
     in both phone/speaker leads.
769











No 74, Vol 3
1934, 17 February
  An Ideal Set for Family Use -
Strapline reads:
     "A Description of an Interesting Receiver
     Employing an Unusual Circuit Arrangement".
PDF download available below.















Suitable enclosure required if mains-derived power is used.
Unorthodox design for which Davey claimed excellent
performance, result of latest update of "family" set
(undertaken about six-monthly):
Initial arrangement shown, with screen-grid RF stage,
     triode as diode detector (cathode to grid, no HT),
     and two transformer-coupled audio stages.
Then three modifications to detector stage described, which
     had been tried in turn for introducing reaction
     (absent in first arrangement), leading to final design.
No constructional details, components list or valve types,
     but circuit diagrams and perspective schematics
     with values given.
Output valve directly heated, with humdinger feed to
     its filament and to other heaters.   Humdinger
     centre tap carries bias components.   Speaker
     is parallel-fed.
Coils unspecified, but two similar MW/LW coils shown;
     matched pair recommended for ganged tuning.
1030



















No 84, Vol 4
1934, 28 April
  From Moving Iron to Moving Coil -












Hints on making the best of moving-coil speakers:
Davey notes the need to match low-impedance speakers
     to output valve with transformer.
Causes of distortion (often masked by moving-iron speakers)
     to be sought in overloaded or worn-out output valve,
     or inadequate output transformer.
If increased HT could be provided, higher-rated output valve
     could be worthwhile for greater volume;
     moving-coil speakers less sensitive than older
     balanced-armature types.
Readers encouraged to buy a good speaker, and to beware
     of out-of-date or liquidated stocks.
170












No 114, Vol 5
1934, 24 November
  Keep Contacts Clean (not on Davey's list) -







Article prompted by a troublesome 2-valver in which
dirty LT switch was not shown up by voltage measurements,
but would easily have been traced with current tests:
Components benefiting from being kept clean are listed,
     including all types of switches, variable resistors,
     older fixed resistors of clip-in type, valveholders,
     and terminals of all types.
355







No 123, Vol 5
1935, 26 January
  Reaction Arrangements for Short Waves -


























Several circuits described for smooth control of reaction,
essential for short-wave listening:
Throttle control: reaction capacitor connected from
     HT side of reaction coil to ground.   Alternatively,
     connect reaction capacitor across an RF choke in
     anode circuit, but neither side of this could be
     grounded to avoid hand-capacity effects.
Further arrangement shown in which aerial input is led to
     anode circuit.   Neither tuning nor reaction capacitor
     could be grounded, so extension spindles and screening
     are recommended.
Armstrong super-regenerative circuit described.   This
     offers an increase in sensitivity right up to point
     of oscillation, and Davey reports on its revival
     for use on the 5 to 7-metre wavebands.
Two forms of resistance control of reaction discussed,
     both amount to controlling HT voltage.   Davey
     recommends these for experiment, but advises good-
     quality variable resistors to avoid noisy performance.
Two arrangements for grid-leaks finally described.
     In the first, LT supply is connected across ends of
     potentiometer, whose slider is connected to LT end of
     grid leak.   Potentiometer adjusted for smooth control.
     In the second, two parallel grid leaks shown: one
     from grid to ground (itself connected to LT+ve); the other
     connected to common HT/LT negative.
672


























No 124, Vol 5
(Cover shows Vol 6)
1935, 2 February
  Using Mains Units with Short-Wavers (not credited) -


















Suitable enclosure required for protection from mains.
Davey notes that mains units had only recently found
favour for use with short-wave sets, and describes ways
of overcoming difficulties in their use:
An effective output filter recommended for use with
     headphones, and useful for loudspeaker also in
     combating hum.   2μF capacitor in each output lead.
Adequate decoupling essential for stability.   Arrangement
     shown for detector stage also giving control of HT voltage.
     HT supply is taken from slider of 50kΩ potentiometer
     wired across supply.   2μF capacitor from slider to ground.
Decoupling of other stages also recommended.
Add-on smoothing circuit for mains unit described, giving HT
     outputs for different stages, ideally in screened enclosure.
Filters for mains-borne HF described.
Davey comments on rise in popularity of all-mains short-wave
     sets, resulting from development of efficient indirectly-
     heated valves.
722


















No 125, Vol 5
1935, 9 February
  About Tuning Coils (not credited) -

















Davey comments that low-loss materials spell increased
     reliability in tuning arrangements for short-wave work.
He argues for interchangeability of plug-in coils of
     differing manufacture, for convenience of amateurs.
One range of ten plug-in coils (Bulgin) is noted, with
     a switch unit available which allowed one of any
     five coils to be put into circuit.
For short-wave work, Davey recommends good-quality
     tuning capacitors with vanes spaced to minimise
     noise caused by dirt, pigtail connections to moving
     vanes, and smooth-acting bearings of suitable material.
Smoothness of operation, and freedom from noise, equally
     important for slow-motion dials.
Requirements less critical for reaction capacitors, but
     cleanliness recommended to avoid noise due to
     HT leakage.   Series capacitor recommended
     as extra safeguard.
769

















No 131, Vol 6
1935, 23 March
  An All-Mains Short-Wave Three-Valver (not credited) -
Strapline reads:
     "An Article Describing a Simple but Efficient
     Receiver which Tunes from 13-85 metres with
     Wavechange Switching".
PDF download available below.









Suitable enclosure required for protection from mains.
Earliest Davey prototype seen illustrated so far:
Davey claims to have received US stations on this set.
Plywood baseboard, ebonite front panel and rear terminal
     strips; base and panel copper foil covered.
Lissen triple-range coil (SW bands, R); 2 x RF choke;
Interstage transformer, output transformer, speaker.
Tungsram HP4100 (RF pentode), tuned anode coupling;
Tungsram AR495 (detector triode) with reaction;
Tungsram AP495 (output triode) or APP4130 (output
     pentode); transformer coupled to detector.
Circuit diagram, layouts, photos and components list.
Power supply included in circuit diagram (voltage doubler
     for HT), but is not described in detail.
19














No 133, Vol 6
1935, 6 April
  A Three-Valve Short-Wave Portable -
PDF download available below.












Portable set useful in exploring effects of weather, buildings etc:
Phones suggested as more appropriate for experimental work.
Plywood baseboard, four pillars supporting top control panel.
     Assembly housed in case.   Optional rod aerial of
     4BA studding lengths.
Coils (each SW band, R) wound on old valve bases, plugged
     into valveholder on top panel; no details for winding.
Osram "K" or Hivac Midget valves specified for compactness;
     no type nos. given.
Variable-mu RF tetrode buffer stage, triode detector with
     reaction, transformer-coupled to pentode output
     stage with phones.
Circuit diagram with most values, simple layout drawings.
80













No 135, Vol 6
1935, 20 April
  At the Short-Waver's Bench, 1 (not credited) -

     First of 13 articles under this title, appearing
     almost every week until 27 July 1935.
















Idea for quickly changing grid leak during trials - crocodile
     clips screwed to grid and LT+ve terminals
     of valveholder.
Reminder to keep pins of plug-in coils clean and open
     them out a little to maintain good contact.
Use of old 2-pin plug-in coils as RF chokes suggested,
     especially for suppression of mains-borne interference.
     Unsafe by modern standards - purpose-made
     components should be used for mains suppression.

Use of plug-in coil in aerial circuit as wave-trap (with pre-
     set capacitor in parallel) to suppress strong local station.
Choice of loudspeaker important for short-wave work:
     Davey finds bass response of moving-coil types
     too great for searching, and suggests use of old
     horn-type speaker for this purpose.
Arrangement shown for variable bass cut: switched
     capacitors in series with speaker.
High-ratio reduction drive recommended for tuning
     below 20 metres.

145



















No 135, Vol 6
1935, 20 April

(same edition as above)
  Short-Wave Meters -



















Usefulness of accurately calibrated wave meter in
station logging outlined.   Use of high-quality
components and robust construction stressed.   Home-
made coils with switched tappings suggested (no details).
Autodyne circuit described, in which screen-grid valve
     with tuned anode circuit is made to oscillate;
     screen grid supply at higher voltage than anode.
Additional circuit shown having second coil in grid circuit.
Calibration explained: graphs drawn up plotting known
     transmitter frequencies against dial readings.
Usage of meter explained: meter tuned until its whistle
     is imposed over unknown station heard on receiving
     set.   Alternatively, meter may be tuned to required
     frequency, then receiving set tuned to match.
Mains-powered meter suggested.
Suitable enclosure required if mains-derived power is used.
     Directly-heated valve used.   Mains hum
     modulates oscillator's output.
Two circuit diagrams with some values.
146



















No 136, Vol 6
1935, 27 April
  At the Short-Waver's Bench, 2 (not credited) -























Simple RC coupled audio booster stage for short-wave
     listening:   Small baseboard, with valveholder,
     associated components, leads to main set, and
     speaker output terminals.
Idea for short-wave detector stage:   RF pentode as
     sensitive leaky-grid detector, with RC or
     resistance-fed transformer coupling to next stage.
     High resistance in anode circuit, and resistance
     in series with reaction winding for smooth
     reaction control.
Neutralised RF stages:   Davey reminds readers that
     inter-electrode capacitance had formerly been combated
     by neutralising circuits, and gives three circuit examples.
     Experiments on similar lines suggested with screen-grid
     valves, even though they have much reduced inter-
     electrode capacitance.
Automatic treble boost in sets with reaction:   Variable
     capacitor in parallel with primary or secondary of
     interstage transformer.   Both reaction and tone-
     control capacitors are of type with shafts at front and
     rear.   Mounted back-to-back with insulated shaft
     coupling; as reaction capacitance is increased, tone-
     control capacitance is reduced.   Circuit given.
188























No 137, Vol 6
1935, 4 May
  At the Short-Waver's Bench, 3 (not credited) -








     Two-valver with one valve:







Davey remarks that he has temporarily been using short
     aerial   Searching found easier in that Morse stations
     are "not nearly so troublesome".
Suggestions for improving selectivity by providing additional
     tuned circuit to RF stage.   Three circuits suggested.
     Several ways of coupling reaction coil also listed.
Volume control:   Davey recommends volume control at LF
     stage rather than sacrificing volume at RF stage.   Three
     arrangements suggested.
Double triode valve used as leaky-grid detector and LF stage.
     Circuit with values, but no coil details.   HF stage
     could be added for powerful 3-valve equivalent set.
Low-loss components:   Simple scheme for home-made air-
     dielectric capacitors using aluminium plates supprted on
     studding.
Plug for Everyman's Wireless Book (Newnes).
218
















No 139, Vol 6
1935, 18 May
  At the Short-Waver's Bench, 4 (not credited) -



Simple short-wave "superhet" converter:










Idea for all-wave set comprising 2-stage transformer-
     coupled audio amplifier, with two switchable RF and
     detector stages.   Circuit given, with switching
     arrangement, but RF stages not shown.
Pentode RF stage followed by triode detector (kept in
     oscillation), whose output is led to aerial socket
     on broadcast set.   Circuit with most values given.
Old valves as small-value capacitors: Table shows inter-
     electrode capacitances for three Mazda valves.   Use
     of low-loss valveholders or soldered connections to
     pins suggested.
Davey mentions Ostar-Ganz valves with heaters that take
     full mains voltage, and suggests that their heaters could
     be run from HT supply.
272














No 141, Vol 6
1935, 1 June
  At the Short-Waver's Bench, 5 (not credited) -


















Variation on Ultraudion circuit suggested for experiment:
     Reaction controlled by variable resistance in series
     with HT, and filament rheostat.   Reaction settings
     have no effect on tuning.
Band-spread tuning: brief reminder of principle and method
     of use.   Davey recommends adding band-spread to any
     short-wave set that does not have it.
Trouble with All-mains Three-Valver:   Davey reports
     peculiar fault with this set (see Practical Wireless
     No 131, 23 March 1935) when he tried out directly-
     heated output valve.   Loud transients caused loud hum
     lasting several seconds, then decaying.   Davey surmised
     that filament was vibrating.
Hum-dinger principle (for balancing AC supplies to heaters)
     explained, with circuit and diagram.
Care of headphones: simple precautions listed, including
     not dropping them, re-magnetising services, care
     of diaphragms.
330


















No 142, Vol 6
1935, 8 June
  At the Short-Waver's Bench, 6 (not credited) -











Hartley circuit: regarded as vulnerable to hand-capacity
     effects as neither side of tuning and reaction capacitors
     could be earthed, but Davey suggests use of extension
     shafts with earthed metal panel.
Alternative to connecting phones in HT+ve supply: connect
     from HT-ve to LT-ve.   Phones are on earth side of
     circuit, and RF current can be bypassed direct to earth.
     Circuit given.
RF stoppers and bypasses: Circuit given showing how RF
     can be blocked or bypassed at each stage in receiver.
Short-wave earth connections discussed.
357











No 143, Vol 6
1935, 15 June
  At the Short-Waver's Bench, 7 (not credited) -
PDF download available below.







     Two-valver for short-wave newcomer:








Tracing noises:   Noises due to faulty fixed components
     (resistors, transformers, capacitors etc) should be
     ruled out first.   Tuning and reaction capacitors
     should be checked for worn-through solid dielectric,
     rubbing of pigtail connection to moving vanes, and
     noise due to unsuitable bearing materials.   Other
     causes of noise listed, including poor contact at valve
     pins, low-emmision valves, and increasing prevalence
     of atmospherics.
Coil, plug-in type (SW band, R), RF choke, interstage
     transformer, speaker with output transformer.   Valves
     not specified.   Few constructional details, but circuit
     diagram with some values and suggested layout of
     detector stage.   Leaky-grid triode detector with
     reaction ("throttle" control: capacitor from HT+ve
     side of reaction winding to ground), transformer-
     coupled to triode output stage.
382

















No 144, Vol 6
1935, 22 June
  At the Short-Waver's Bench, 8 (not credited) -







     Simple 2-stage amplifier:










Suggestion to use jack plug and socket (rather than screw
     terminals) to connect/disconnect speakers and phones.
Ultra-slow-motion tuning: fit tuning capacitor with slow-
     motion dial of type installed behind front panel, and
     drive it with older-type front-mounted slow-motion dial.
     Accurate logging aided by using both dial readings.
Virtues of using separate audio amplifier to which
     experimental detector stages can be connected.
Circuit with most values.   Triode first stage coupled to detector
     by parallel-fed interstage transformer.   RC coupling
     to output stage.   Davey recommends this arrangement
     as transformer blocks RF from both amplifier stages, and
     bass response is reduced (desirable for short-wave work).
Detector efficiency:   Davey asserts that values of grid leak
     and grid capacitor should be found by trial and error for
     detector valve in use.   Some valves require high-value
     grid leak, but useless unless insulation resistance of other
     components is good.   Recommends pre-set grid capacitor.
410


















No 145, Vol 6
1935, 29 June
  At the Short-Waver's Bench, 9 (not credited) -
PDF download available below.
     Receiver for 20- and 40-metre Amateur bands:




     HF Unit using RF pentode (for interposition between
     aerial and short-wave set with detector first stage):



Summertime listening:   Advice on what can be heard during
     summer months.
Circuit diagram with values; no constructional details.
     Proprietory or home-made coils.
     RF pentode buffer stage, with variable capacitor coupling
     to leaky-grid triode detector (throttle-controlled reaction),
     RC coupled to triode output stage.
Front panel and baseboard (foil covered).
     Circuit with most values, and layout drawing.
     Hints given on adjustment and operation with
     "slave" set.
431











No 146, Vol 6
1935, 6 July
  At the Short-Waver's Bench, 10 (not credited) -
PDF download available below.











     Mains/battery short-wave 3-valver:




Importance of keeping contacts clean.
An aerrial coupling effect:   Davey relates that volume and
     sensitivity of conventional 3-valver (RF, detector/reaction,
     output) were much enhanced when aerial connection was
     wound once round tuned coil of detector stage.
     This prompted suggestion for experimenting with applying
     reaction to RF stage.
Variable control of voltage on RF stage screen-grid: reminder
     that this can serve as useful reaction control.
Position of reaction coil: Advice to place this on former
     between aerial and grid coils, reducing damping
     and aerial movement effects.   Idea extended by
     combining aerial and reaction coils (circuit given).
Battery-powered triode detector; pentode output stage with
     mains power supply.
     Suitable enclosure required for protection from mains.
     Circuit, with most values given.
457

















No 147, Vol 6
1935, 13 July
  At the Short-Waver's Bench, 11 (not credited) -


















Advice to builders of 2-valver featured in "At the Short-
Waver's Bench - 7", (15 June 1935).
     Set may be unstable if high-efficiency valves are used, and
     HT voltage is low.   Decoupling advised (circuit given).
     Threshold howl (at brink of oscillation) - reduce inductance
     in detector anode circuit by parallel-feeding interstage
     transformer (circuit given).
     Aerial dead spots - fit aerial trimmer capacitor, allowing
     dead spots to be eliminated or moved to unimportant place
     on dial.
     Smooth reaction build-up assisted by connecting LT end of
     grid leak to slider of potentiometer across LT supply.
     Hand-capacity effects: earthed foil covering to back of panel.
Short-wave log useful.   Recommended headings: Date;
     time (GMT, 24 hour clock); station received; signal strength;
     readability; signal quality; distance from sender; weather
     conditions; phase of moon; receiving setup (unless always
     the same; sender frequency.
479


















No 148, Vol 6
1935, 20 July
  Quality Equipment -





     Low-power amplifier:


     High-power (PA) amplifier:


     HF and detector unit:



Suitable enclosures required for protection from mains.
Designs prompted by search for quality - two amplifiers, and
HF detector unit designed to operate with either amplifier.
No constructional details given.   Amplifier circuits appear
incomplete.   Most component values given, but transformers,
coils, etc not specified.
Triode first stage, RC coupled to PX4 triode output stage
     (cathode circuit missing, but auto-bias voltage given).
     Voltage-doubler (metal rectifier) power supply.
First stage identical with above amplifier, RC coupled to
     PP5/400 (or PP15/400?) triode output stage (cathode
     circuit missing).   Full-wave valve rectifier power supply.
Pentode RF stage with wavechange, capacitance coupled
     to pentode detector stage with facility for connecting pickup.
     Unit powered by either of above amplifiers.
494















No 148, Vol 6
1935, 20 July
  At the Short-Waver's Bench, 12 (not credited) -







Advice to check capacitors (decoupling, bypass) for
     breakdown, upon trouble with noises, crackles etc.
Idea for coil former using four small combs screwed to 1"
     square wood block.
Report cards: uses explained, and specimen given.
Solid-dielectric reaction capacitors recommended, as air-dielectric
     types can give trouble when dust builds up between vanes.
501







No 149, Vol 6
1935, 27 July
  At the Short-Short-Waver's Bench
     (13th and last of series, not numbered or credited) -







Davey notes trend toward smaller-value tuning capacitors for
     short-wave work, and suggests modifying older capacitors
     by removing plates.
Aerials: Davey reports changing from 40-foot "inverted L" to an
     almost vertical aerial 5 metres high, with good results.
Ideas for making tuning and reaction coils for 5-metre band.
Idea for using porcelain stand-offs to support coils clear of
     metal or foil-clad chassis.
529








No 420, Vol 17
1941, June

(journal now monthly)
  Experimental Circuits -
PDF download available below.

     See similar article in Popular Wireless,
     No 634, Vol 25, 28 July 1934.














Davey recalls some older circuit arrangements suitable for
experiment during wartime, including:
Single-valve "reflex" circuit: valve serves as both RF and
     audio amplifier; two transformers couple anode and
     grid circuits, with diode detector in coupling circuit.
     Davey suggests an (untried) modification for experiment.
DeForest Ultra-Audion: leaky-grid detection; grid signal fed
     from junction of series-connected coil and tuning capacitor.
     Two methods of applying reaction are suggested.
Monodyne: HT+ve connected to earth, and to aerial
     via an aperiodic coil.   Most of circuit thus negative
     with respect to earth; grid leak ran to HT/earth line.
Armstrong and Flewellyn regenerative circuits.
Semi-reflex circuit: crystal detector feeds audio amplifier, but
     capacitor-controlled amount of RF is fed to grid, allowing
     reaction to be incorporated.
Anode and filament input circuits: both "reputed to give
     excellent results".
282



















Downloads for
seven full pre-war
Davey articles
By kind permission of PW Publishing Ltd, and with images either kindly provided by them or British Library images reproduced with permission, the PDF downloads below offer a selection of seven full Davey articles from pre-war Practical Wireless editions.   They are available for your personal non-commercial use.   Please also read the copyright notice on the WELCOME page.   If you wish to pass them on to a friend, please send a link to this web page.   He will then have access to the viewing and printing suggestions as below.

Each download contains the full PW article, with my notes and comments on the design.

PDF files:   (You need Acrobat Reader installed on your PC.)   File sizes range from 2.1Mb to 7Mb, and a broadband connection is recommended.

Click the icon to download the chosen PDF file.   If Acrobat Reader opens within your browser, use the "Back" button to return to this page when download is complete.   If Acrobat Reader opens in a separate window, close that window to return to this page.

The images supplied by PW Publishing Ltd (Downloads 1, 2, 3 and 6) are high-quality digitally cleaned images scanned from unbound editions. I am most grateful to Tex Swann for preparing these images for me.

The British Library images (Downloads 4, 5 and 7) were taken from bound volumes using a scanning rostrum camera.   Whilst they are of lower quality, they are entirely legible, and full of character!   Some of them suffered from distortion at the binding, so I have undertaken some careful editing to reduce this.

The Practical Wireless editions of the 1930s are about 8 1/4 x 11 1/4 inches (209 x 286mm).   The wartime 1941 edition is somewhat smaller.   The images have been reduced in size very slightly where necessary to fit comfortably on an A4 sheet to ensure complete printing.   It is easiest to simply print each page on its own A4 sheet.   Alternatively, you could arrange printout so that pages facing each other in the original magazine still do so.

  An Ideal Set for Family Use Download 1:
AN IDEAL SET FOR FAMILY USE

First published in Practical Wireless on 17 February 1934; reproduced by kind permission of PW Publishing Ltd.
Images kindly supplied by PW Publishing Ltd.
Unorthodox design for which Davey claimed excellent performance, the result
of his latest update of the "family" set (undertaken about six-monthly).

  An All-Mains Short-Wave Three Valver Download 2:
AN ALL-MAINS SHORT-WAVE THREE-VALVER

First published in Practical Wireless on 23 March 1935; reproduced by kind permission of PW Publishing Ltd.
Images kindly supplied by PW Publishing Ltd.
The earliest Davey prototype seen illustrated so far:
Davey claims to have received US stations on this set.

  A Three-Valve Short-Wave Portable Download 3:
A THREE-VALVE SHORT-WAVE PORTABLE

First published in Practical Wireless on 23 March 1935; reproduced by kind permission of PW Publishing Ltd.
Images kindly supplied by PW Publishing Ltd.
Portable set useful in exploring effects of weather, buildings etc, and
for assessing the performance of a nearby transmitter.

  At the Short-Waver's Bench - 7 Download 4:
AT THE SHORT-WAVER'S BENCH - 7

First published in Practical Wireless on 15 June 1935; reproduced by kind permission of PW Publishing Ltd.
British Library image; Copyright © British Library Board: Shelfmark: LOU.LON 642 [1935].
First of three articles selected from Davey's 13-part series published April to July 1935.
Noises in the Short-Wave Set - hints on tracing elusive noises in short-wave valve sets.
Two-valver for the Short-Wave Newcomer - a conventional set with good performance for the beginner.

  At the Short-Waver's Bench - 9 Download 5:
AT THE SHORT-WAVER'S BENCH - 9

First published in Practical Wireless on 29 June 1935; reproduced by kind permission of PW Publishing Ltd.
British Library images; Copyright © British Library Board: Shelfmark: LOU.LON 642 [1935].
Second of three articles selected from Davey's 13-part series published April to July 1935.
Summer Listening - advice on what can be heard during summer months.
A Special (3-valver) Set for Amateur Bands - a set for the 20-and 40-metre bands.
An HF Unit for ShortWaves - an "add-on" unit to a receiver having a detector-with-reaction first stage.
Conditions on Short Waves - a note on the effect of the weather upon short-wave reception.

  At the Short-Waver's Bench - 10 Download 6:
AT THE SHORT-WAVER'S BENCH - 10

First published in Practical Wireless on 6 July 1935; reproduced by kind permission of PW Publishing Ltd.
Images kindly supplied by PW Publishing Ltd.
Third of three articles selected from Davey's 13-part series published April to July 1935.
Dirty contacts in the short-wave set - the importance of keeping contacts clean.
A curious aerial coupling effect - a simple experiment to increase volume and sensitivity.
Variable control of the screening grid - a reminder that this can serve as a useful reaction control.
The position of the reaction coil - advice to place this on former between aerial and grid coils.
Mains-fed output stages - battery/mains set with pentode output stage.

  Experimental Circuits Download 7:
EXPERIMENTAL CIRCUITS

First published in Practical Wireless in June 1941; reproduced by kind permission of PW Publishing Ltd.
British Library images; Copyright © British Library Board: Shelfmark: LOU.LON 398 [1941].
Davey recalls some older circuit arrangements suitable for experiment during wartime.


BACK TO TOP
CONTACT ME
Whilst Davey’s post-war writing and broadcasts are well remembered - as attested by the dozens of reminiscences I have received - it seems improbable to me that at this distance in time there are many left who recall his pre-war writing.   But I would be delighted to be proved wrong!