Atwater Kent Model 30 Question

[DavGoodlin]

With all the High MFD caps from my car stereo, I added 27,000 and 36,000 MFD to the A supply, its finally quiet. I like the battery idea for short demos, but they go down quick.

The coil is ordered and a resistor is in place of it. Several stations now are pretty clear, but not room-filling loud. Could it be that the Radiola 100A speaker may not be the right one to use with the 71A output tube?

[Kevin Kuehn]

A 71A should drive the 100A very well. There is an adjustment on the driver pin/magnet gap on those 100A's that can have quite an effect on volume, but it's been too long since I messed with one to remember the adjustment procedure. If the speaker works well with other radios, then I wouldn't mess with the adjustment. Those 100A speakers were one of the best sounding of the day, almost hi-fi by period standards.

[DavGoodlin]

Thanks everyone! I got a 6v rechargeable battery and now the hum is gone. My 130 foot antenna is about 20 feet above ground gets good day and night reception. The 71A tube drives the speaker loud enough for weak stations.

What I find odd is that many of late-20s AC sets had tubes (27s and 45s with direct-heated cathodes) with filaments served from a dedicated transformer winding. There are hum controls in the 27 and 45 filament circuits on the Temple 8-60 I just picked up. it appears to be a means to cancel hum on the filament by varying grounding reference of the cathode.

This was the first TRF set I ever tinkered with. What an experience!

[polyphase]

A final observation if I may..

I had a Stewart Warner 385, which is much like the AK30 in
that it had 6 tubes (71A output) and the 3 tuning caps
ganged together.

This set had poor sensitivity which I traced to mis-alignment of the tuning caps. I recall I had to loosen some set screws and slightly move the individual caps, one at a
time, to get maximum output from a good station and then re-tighten the screws.

Thereafter I got good perfomance from a 15ft indoor antenna (actually the aluminum track of the window blinds). I still use this antenna but now with a 5 tube Arborphone 27.