Well, here's another one.
No sch.
No info.
The tube lineup is 4 tubes, 12BE6, 12AT6, 50B5 and 35W4.
Very similar to some other cheap miniature tube-based ones.
The oscillator arrangement is the same as in the Garod I just finished.
No frame/mag antenna
Now the radio receives the strong local station and judging by the tuning cap position it is in the vicinity of where it should be.
The problem is two-fold: 1) no other stations meaning very low sensitivity, 2) strong hum. Changes with volume, no change due to the tuning.
Would really like to have the sch.
Update: from what I saw I thought the IF alignment could be way off, as after replacement of the Be6 tube that is very weak things did not improve.
So I alugned it roughly, without digital readout from my oscillator, just setting it to 455kHz. I first tried to peak out what the radio was aligned to and it was waaaaay of, and all these guys were 455kHz, so I aligned it, and what do you know, the radio now is receiving fine across the dial with me touching the antenna.
It is not supersensitive, and what could one expect from an AA5 4-tuber with the IF amp tossed out.
But it does almost as well as my tabletops with me touching the antenna.
There's still the issue of the hum. While not heard during reception it is quite noticeable while between stations.
But without the sch I might let it alone.
(12-31-2016, 09:09 PM)morzh Wrote: [ -> ]Update: from what I saw I thought the IF alignment could be way off, as after replacement of the Be6 tube that is very weak things did not improve.
So I alugned it roughly, without digital readout from my oscillator, just setting it to 455kHz. I first tried to peak out what the radio was aligned to and it was waaaaay of, and all these guys were 455kHz, so I aligned it, and what do you know, the radio now is receiving fine across the dial with me touching the antenna.
It is not supersensitive, and what could one expect from an AA5 4-tuber with the IF amp tossed out.
But it does almost as well as my tabletops with me touching the antenna.
There's still the issue of the hum. While not heard during reception it is quite noticeable while between stations.
But without the sch I might let it alone.
< with me touching the antenna.
It's your magnetic personality!!!!!
ps I'd stay inside during lightning storms!!
I am still looking online for any info but there is NOTHING!
When are you going to stop buying undocumented junk and start buying respectable radios with proper papers?
Carl
Thanks. In fact from what I saw the 153 looks very close.
While I was trying to figure the hum out the 35W4 rect tube quit.
But the 153 sch is indeed close. Very few things are different.
Carl, thanks again.
http://www.nostalgiaair.org/Resources/772/M0021772.htm
Well, I can't seem to help the hum.
The schematic at the linkmis very close, practically the same, and no matter what I do the AC hum persists.
The hum stops when I short the grid of the 12AT6 (pin1) to GND.
IF it is disconnected with the 10M resistor to GND it hums, if connected and the volume pot is in the low position, the hum gose away, in high position the hum is pronounced. The reception is fine.
Oh, if the output tube's grid is disconnected the hum stops. So it likely comes from the 12AT6.
I replaced 10M resistor with 100K one, the hum went down quite a bit with the reception still being fine.
But all in all, I am not sure why the hum is there. I tried a cap from AC lines to chassis, or across the lines, or parallelling capacitor across the electrolytic.
If it is a result of AC lines routing....it is where I think it was originally.
Heck with it, maybe it was designed to hum.
(01-15-2017, 09:35 PM)morzh Wrote: [ -> ]http://www.nostalgiaair.org/Resources/772/M0021772.htm
Well, I can't seem to help the hum.
The schematic at the linkmis very close, practically the same, and no matter what I do the AC hum persists.
The hum stops when I short the grid of the 12AT6 (pin1) to GND.
IF it is disconnected with the 10M resistor to GND it hums, if connected and the volume pot is in the low position, the hum gose away, in high position the hum is pronounced. The reception is fine.
Oh, if the output tube's grid is disconnected the hum stops. So it likely comes from the 12AT6.
I replaced 10M resistor with 100K one, the hum went down quite a bit with the reception still being fine.
But all in all, I am not sure why the hum is there. I tried a cap from AC lines to chassis, or across the lines, or parallelling capacitor across the electrolytic.
If it is a result of AC lines routing....it is where I think it was originally.
Heck with it, maybe it was designed to hum.
Mike;
Maybe it has some heater to cathode leakage in either the 50C5 or the 12AT6 tubes? Try some tube substitution.
I did, Arran, the first thing I did amongst others was swapping the tubes. Nope. No dice.
Hey Mike, I have one of these radios and it is hum free. If you need a picture of the layout or any other info let me know.
Gregb
Greg
Would be much appreciated. By chance do you have the exact schematic of it? I mean, the Sterling? I am going by that Teletone documentaion, it is 98% the same with minor differences that I do not think account for what I am seeing but still.....
Mike
I don't have a schematic for it. Tonight after supper I will get a picture of the chassis layout and post it here.
Gregb
Here is picture Mike, hope it helps.
Gregb