[morzh]

Well, in the declining years folks sometimes tend to use what disposable income they have left to pamper themselves to their youth's dreams which they had no money when they were young and no time when they were mature.
After all money is not to be taken to the grave, so why not treat oneself to one or two luxuries that we salivated all over in our teens...

[morzh]

My memory had not failed me when I was writing about those inductances. I found them, both 5.6mH and 10mH, both small axial ones.
So, I think, I will use the 10mH one; it is about 47 Ohm (which I think is not even important) and about 40mA (which is way more than I need there).
Today I could not do anything: came home, cook the meal, took out the recycling (ours is every other week, so it is lots of it), called mom...by then it was already 8pm.
Not today, no...

[morzh]

So, I sat down, and first tried 40 AWG wire. It broke quickly. I retook diameter: this one was 0.05mm whereas the one I took off was 0.08 to 0.09mm.
I took AWG 38 I have, which is 0.09 to 0.1mm, and in 30 minutes or so put manually 580 turns (it was 700). Condisdering this is a filter choke, this should be just fine.

I took the ohhmeter to it, and it gave me 64-65 Ohm (66 is the target), so that was right on, and the inductance on my LCR was 5.2mH (my first calculated value on one of the inductance calculator was 6mH).

So it is just fine.
I took a candle and heatgun and potted the open wire.

Tomorrow I will connect it back and try to power up.

   

[radiorich]

Hello mike,
Nice job hopefully it works and I am sure it will.
Sincerely Richard

[Arran]

Mike;
Where was this RF choke located? I remember seeing on a few sets that had detector-amplifiers ahead of the power output stage that that they often had an RF choke involved to prevent IF interference from getting into the audio (at least it think that was what it was for). Sets that had a proper second detector diode, or pair of diodes didn't need it so much.
Regards
Arran

[morzh]

http://www.nostalgiaair.org/PagesByModel...001491.pdf

The 66 Ohm filter in the 1st detector's plate circuit.
Look in the early version sch.

   

Here it is, the spiral that marked 66 Ohms.

I should've just used that 5.6mH or 10mH small inductance I have, but then I just wanted that a bit more original...absolutely no reason for it.

[morzh]

Almost decided ot turn it on, but didn't like the power switch being 50 - 100 Ohms, so it is the same exact switch as in 96, and I gave it the same exact treatment: sprayed D5 into the small opening under the domed lid from both sides and worked it a bit.
Tomorrow then.

[radiorich]

Hello Mike,
that D5 is great for switches and I do the same I will try spraying it through a side hole first before taking it apart .

Sincerely Richard

[morzh]

That one cannot be taken apart well. It is riveted. But the domed switch luckily has some spacing (not much and not intentional), and oen could even see the actuator move through it.
This is what I use.

[radiorich]

Hello mike,
that is lucky that you were able to do that !
I have one of my radios that the volume control is getting scratchy again hopefully it's does not have bad spot .
Sincerely Richard

[462ron]

Interesting design in that the plate circuits of the first detector and IF stage take full B+ right from the filament of the 80 rectifier with only small resistances in series of coils and IF transformer. The negative end of the power supply from the center tap of the power transformer going through a series of resistors and the field coil instead of putting the fc in the B+ side, my Philco 37-116 has a similar design!

Ron

[morzh]

So...

4 out of 5 resistors in the resistor section were too much off, so I had to fix it.


I opened up the caps, removed the rod, and then parallelled the proper value resistor to them. Pretty much using them as solder posts.
   

Then I soldered them back (the caps were already soldered and re-soldered to, so they are abut ugly) and, after having manufactured the insulating pressing gaskets from fishpaper (there was one original, but it was brittle, and I need two with extra resistors soldered) I put the back.

   


Then I eventually powered the radio up, and heard nothing but hum. The signal from the generator would not come through. Neither IF, nor the BC frequency.
The oscillator was fine, and the rest of everything checked out fine.
Then I put the scope on the 2nd detector Grid cap...it showed good signal when the radio was tuned to the frequency. All of a sudden the modulating beep slowly rose up and the signal became large.
I was able to tune the local station.
Then I removed the scope clip from the Grid cap, and the signal slowly faded away.

I am not sure what I did, but eventually the signal stayed.

So I removed the tubes, took Qtips, D5, and cleaned every single tube socket pin and tightened those that I thought were too wide.
Will let it dry and retry tomorrow.

The signal has some distortion. There could be two reasons:

1. The AK uses Plate detector
2. The speaker has been repaired (the cone), and the adhesive seems to be tar. I might procure a newer speaker or send this one for being re-coned.

[morzh]

OK, it worked, but there is that hum issue.

I traced it to the balancing resistors from the 47 tube's filament to GND.

   

They are supposed to be 10 ohm (the sch shows that).
Removing the GND center removes the hum almost completely, but, of course, it is not right as the filament should be referenced to GND.

When I desoldered one resistor, it showed 5 Ohm from the center, and the one I did not desolder was 10 Ohm from the same point.
Upon desoldering it, both became 5 Ohm. The fact it was soldered by one end could not change that.

So, I am hesitant to solder it back as I suspect there is some issue in the resistive wire going to the lugs.
I have ordered 10 ohm resistors and will solder them instead tomorrow.