A Five-Valve Browning-Drake

Radio Record, Volume II, Issue 10, 21 September 1928, Page 28

A Five-Valve Browning-Drake

Successful Home Construction

N enthusiastic South Island constructor, writing under the nom-de-plume "Satisfied Constructor," forwards a photograph and report of the 2R.F. Browning-Drake receiver which he has constructed, including the amplifier in the same cabinet, making the complete 5-valve set. The cabinet certainly does our correspondent credit, and extracts following from an interesting and lengthy report show that reception performance is correspondingly good. " BUILT the 2R.F. Browning-Drake recently described by you and you will be interested in the following report. The volume is tremendous, and it beat a 7-valve néutrodyne for distance and volume, both tested out on the same aerial (a 87-foot high 60-foot long T), but before I secured these results I had a bit of trouble, which one can ohly expect when making up a new eircuit. I altered the lay-out slightly and instead of a wood base-board with copper covering I made up a solid brass (1-16in.) base with sides turned down 1iin. I think for all the extra expense it would be far better for constructors to carry out this plan. "Y wound all the coils with No. 22 D.C.C. wire supported with celluloid strips. I did not space the turns, as I eonsidered the covering to be sufiicient, and from results I think it is. The tuning condensers are W.R.C. The neutralising condensers are also W.R.C. midgets with all plates re-

moved except one fixed and one moving. I am using a rotating tickler.. "Audio is transformer coupled, all built on the one base, making a complete receiver. The panel is a fornier 24 x 83 x 38-l6in. with a 26-gauge copper shielding on the back.

"When I finished building it and switched on, all I could get from it was a high-pitched whistle. If I coupled a .002 condenser across the grid of first audio value to A- the whistle stopped, so I took out the first audio transformer, an All-American 5-1, and

fitted a Jefferson 2-1 in its place; the whistle stopped. I still retained a 8-1 All-American in last stage, so I tuned in 3YA, and then neutralised. No signal would come through, even with the tickler turned full in. I considered this a good test, but when I tuned in a low-powered station in Sydney and pushed the volume up with the volume control with tickler set well back, the R.I. valves would oscillate, so I went over the balancing again but it was all the same, so I tried connecting a No. 2 Hmmeostat between grid and N.C. of first R.. valve. That gave it full volume and better tone. I am using 16 turns No. 380 enamelled buneh-wound primary and 38 Mullard P.M.5X valves, 1 Geco first audio and a P.M.6 last audio. "T am using a Philips power-plus B eliminator and a Philips baby grand loud-speaker, which are splendid instruments. "There is very little background noise and in between items it is so silent that you would have to stand with your ear to the speaker to hear any hiss. You might think I am ‘stretching it,’ but it is true. It is a wonderful dis-tance-puller, I heard 1ZQ, Auckland, at good speaker strength on Thursday, August 30. I never heard this station before, even when using an 8&-valve super-het. In two nights’ searching have heard 21 stations, including three Japs."