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

Philco 118 AVC Levels
#1

I have been chasing an AVC level issue on a 118 that I have completely recapped, resistors checked, tubes checked, and recalibrated. I find that the AVC level rarely gets above -3VDC and often will slip positive approx 1.5 VDC with no signal. I am looking for guidance as to whether a slight positive voltage is normal on the AVC bus with no signal and if not, suggestions as to where to begin my investigation. I thought AVC was always in the range of zero to negative values. Thanks for all of your help and guidance.

Gary
#2

Average AVC voltage is highly dependant on incomming signal level.
Weak signals will make the AVC hover near zero (max gain), like is should.

Since this set needs (and was designed for) an outdoor aerial of at least 30ft.,
I suggest trying that. Be sure to also use a lightning arrestor and install it properly.
Also very inportant is a good Ground on the set to a cold water pipe or ground rod.
This will also maximize your receiving signal strength.


Chuck
#3

Thanks for the response. I do have a 100 ft long wire on it although no ground. The receiver sounds good on AM and SW bands so I tend not to tamper any further. The shadow meter functions good for the most part but really only narrows up on really strong signals. I measured the AVC on the left side of the 2 meg resistor R15. I just wasn't sure that AVC should swing slightly positive like it does when it is at max gain.

This radio was quite the challenge but I am very pleased with its performance so far.

Gary
#4

Makes a lot of difference with what type of meter you are using. Going positive goes against the 'book' but I don't have enough knowledge to address this specific model.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 60 Squealing
I seem to remember eliminating a squeal by changing the IF frequency by a few KHz. Not that you should put too much tru...fenbach — 08:48 PM
Philco 42-390, code 121 speaker
These speakers pop up on eBay regularly, even if at bloated prices. Honestly, have not seen many parts on swapmeets.morzh — 08:38 PM
Philco 38-7 Speaker
The put-put is not like the speaker problem.morzh — 08:29 PM
Mission Bell Model 19A Car Radio
Hello everyone,  As mentioned in my last post I was going to see if the vibrator / rectifier section could be persuaded...Antipodal — 08:21 PM
Philco 60 Squealing
Wondering if I did it backwards. If a coil was wound backwards, the oscillator would not work at all. Old school...Chas — 07:23 PM
Philco 38-7 Speaker
4-ohm speaker. Black, Green leads.tludka — 07:00 PM
Philco 42-390, code 121 speaker
#87 on the schematic.  This radio had a 8" Zenith  speaker attached to it when I got it. I do don't know the hist...Stevelog — 06:39 PM
Philco 60 Squealing
I'm pretty sure I now have the litz wire soldered. This did not make any difference. Back in April I rewound the seconda...dconant — 06:25 PM
Philco 38-7 Speaker
Just to make sure, you chose either 4 ohm into 5K or into 10K? (blk-org or blk-grn)morzh — 06:23 PM
Philco 38-7 Speaker
I have let this one sit because of other duties. Now I am back, and I have a couple of questions. I hooked up a Hammond ...tludka — 05:34 PM

[-]
Who's Online
There are currently 2831 online users. [Complete List]
» 2 Member(s) | 2829 Guest(s)
AvatarAvatar

>