Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

38-610 Code 126 signal issues
#1

I've been working on this set for a few days now. I don't have the service packet from Chuck yet, but the radio is essentially the same as the schematic from the Code 121-122 schematic.

I finally have the radio stable enough that all three bands are good, except above 19 MHz, where the LO seems to die. I'm going to order a new 6A8 to try to take care of that.

Also, I now have enough gain to get some noise floor on all bands.

Now here's the fun part(s):

With no antenna attached, I get signals on all bands, but at lower volume levels.

With my random longwire attached, the stations get very much louder. The AGC is developing good negative voltages to the grids of the 6A8 and 6K7. Unfortunately, that voltage does not seem to actually DO anything to regulate the input signal.

Add to this that when the longwire is connected, I have input overload across the BCB to the extent that there are spurs all across the dial.

The antenna coils all seem to be fine. The primaries are all continuous and the secondaries are continuous and also tune properly.

The 6A8 cathode resistor measures 106 ohms, whereas it should be 100 ohms. Well within tolerance.

Any ideas? This one really has me scratching my head. Other than the total lack of AGC action (despite a good range of voltages being developed: -1.5 to -13.5V), the set seems to perform quite well.


Messages In This Thread
38-610 Code 126 signal issues - by BrendaAnnD - 05-01-2014, 02:36 AM
RE: 38-610 Code 126 signal issues - by BrendaAnnD - 05-01-2014, 01:28 PM
RE: 38-610 Code 126 signal issues - by gregb - 05-02-2014, 04:12 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco Model 38-7: what caps & resistors do fail typically?
Since you stated earlier, you have a console 38-7XX.  They also had a 38-7T (table), and 38-7CS (chairside).  A very nic...GarySP — 01:18 PM
Part numbers to model cross
That I wouldn't know, but sometimes the radio document itself shows one, same as the capacitor cans' etc pinouts.morzh — 12:46 PM
Part numbers to model cross
Thank you morzh, that is exactly what I was looking for. Now , is there some where that shows pinouts for Philco power ...Jim Dutridge — 11:37 AM
Restoration of the Canadian General Electric A-87
Thanks for your help Michael. In fact, this video is only an intermediate result. Later I had to apply another tinting l...RadioSvit — 09:01 AM
Restoration of the Canadian General Electric A-87
Great job on the cabinet. PS. In the US notation, "kenotron" refers to specific type of tubes; we call re...morzh — 08:24 AM
Part numbers to model cross
This document has at least some tables of models and parts used. Example: Choke 32-7572, used in 604 radio. Search f...morzh — 08:19 AM
Restoration of the Canadian General Electric A-87
I also checked all the radio tubes on my Hickok 530 tube tester. The 5Z3 kenotron turned out to be faulty, all the other...RadioSvit — 08:02 AM
Restoration of the Canadian General Electric A-87
Well... While the varnish is drying up, I started repairing the chassis... Of course I started by replacing the pa...RadioSvit — 07:12 AM
Philco Model 38-7: what caps & resistors do fail typically?
Hello Martin, Welcome aboard our little community what great Model 38-7 Sincerely Richardradiorich — 12:30 AM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum Martin. I count about 9 paper caps, the 3 electrolytic caps and 2-Y2 safety caps to replace th...RodB — 09:44 PM

[-]
Who's Online
There are currently no members online.

>