[MrFixr55]

Hi Mike,

Make sure of a couple of things:

If you have another battery TRF set, test the tubes in that set.

Make sure that the 2 transformers in the 3 Tube TA are not coupling to each other. They need to be placed "orthogonally". Having one standing up and the other laying down should help. This is what they did in the transformer can of the RCA Radiola 16, 17, 18, etc.

Run the set with only the 2 AF tubes. There should be no "whistle" no matter how high you turn up the filament resistors.

Add the detector tube. Touch a wire to the condenser / secondary coil input to the detector TA (Left hand side terminal closest to the detector tube, marked "In"), and try to tune in a station with the rightmost tuning cap. If there is a strong station nearby, you should get it. At least, you should not get the whistle

Add the 2nd RF amp and touch a wire to the grid terminal of that tube. Try to tune using the center and right condensers. You should get a station.

Finally, add the first RF Amp and repeat.

The AK20 had 1K wirewound resistors between the grid of each stage and the junction between the stator of the cap and the "high" side of the secondary of the RF transformer. Both A-K and RCA had problems with TRF sets oscillating. Also remember that these sets are not neutralized.

If the set oscillates when adding a tube, swap out that tube.

You can also "signal inject" to check out the radio. Use a transformer between the signal (CD Player, etc.) and the stage that you are injecting into. If injecting into the grid of the 1st audio amp, you should hear the audio that you are injecting. You will also hear a signal if you inject it directly (through the transformer) to the grid of the detector

[morzh]

MrFixr

I have both transformers standing, at an angle.
I am sure they don't couple much as these have close magnetic circuit. Theoretically they can, but I doubt it.
I also think, the whistle starts only when all tuybes are in; when only the detector and two audio are in, there is no whistling.

I use 22V as per ARBE's recommendation.
All schematics and the Ak10A diagram in the manual, as I said before, recommend 45V on the detector. I do not see harm in it. But somehow they called it +20.

Tomorrow. Today is too late, I am tired.

[MrFixr55]

Hi Mike,
Try 45V on the detector if you are using a 201. If a 200, then 22.5 is correct. Note that they also say 40 for the other 2 tubes in the TA 3 Tube Island. However, if you try to run the set on 45V for all tubes, pe prepared to use head phones. I would start out by trying 45V on the detector.

Newer versions of the AK10, especially the 10C but I think the B also used "Orthogonally" mounted RF coils where ine coil is standing up, one is aligned forward and back and the last is mounted left and right.

If you get a signal now but it breaks into oscillation, try 67V on all the tubes except the detector and see if that stops the whistling.

[morzh]

I use 201A

[morzh]

So, what I did was, first I took out both RF tubes, and tried the "antenna" (OK, a spool of wire with about 4-5' straight piece of it at the "IN" terminal of the island amp). No reception. Then I put my finger on the terminal and got the reception.
https://www.youtube.com/shorts/E5d05qvjjzI

[morzh]

then added the second RF tube.
https://www.youtube.com/shorts/AtqsvEWRDPI

[morzh]

then the 1st RF tube.
https://www.youtube.com/shorts/vrVw-cjTzyg

[morzh]

This is a short music clip

https://www.youtube.com/shorts/hixfifu-SaI

Of course, the radio is not fully tuned and aligned (if it can be).
I need to look at the microphonics, at the reception, learn the optimal potentiometers positions etc etc.
But it receives, and with a good antenna I suspect it could be somewhat decent.




Hey Ron!

That one's for you, man!

[radiorich]

Hello mike,
that Sounds good I guess I will need to work on my AK maybe this winter !!
Sincerely richard
P.S. I have never worked on a AK before mine does work I brought it up on the variac .

[morzh]

Rich,

What model AK is it?

[radiorich]

Hello Mike,
From what I’ve read, this appears to be an Atwater Kent Model 85 in a lowboy-style cabinet. It came from a family where it spent its entire life in one home. I’m the second owner, and I also got a Zenith tabletop from the same family.

Sincerely Richard
P.S. the family farm house is still on the road that was named after the family where this radio came from.

[Arran]

Rich;
Is your A.K a model 85, which is an AC set, or an 85Q which is a battery set?
Regards
Arran

[Arran]

Mike;
The set sounds pretty good for a first power up. This model 10A is a perfect example of why single dial tuning was such a big improvement just a few years later. It also illustrates why they made such a big deal out of "screen grid" tubes, more gain, less feedback, this was why so many of these early sets had a rheostat to adjust filament voltages for each stage. I did think that they had feedback neutralizing condensers to prevent the oscillation, but maybe that was on the model 20 and later A.K and RCA sets?
The microphonic issue was also why they quit making tubes with globe style envelopes, which why it's ironic how audiophools seem to gravitate towards them, also demonstrating how technologically illiterate they are. If type #50s were really "the bomb" with high fidelity why did they replace them with #45s, 2A3s, etc.? For that matter pentodes and beam power tubes are much more complicated to make then triodes.
Regards
Arran

[morzh]

Yes, I just found an article on UX-201A, where the guy is evaluating it for audiofiles' purposes.
I honestly don't get it.

[morzh]

Wow...1,740 views on that music clip video.

Should I retire, monetize the channel and become a bloger?
Whad'yall think?