Plate voltages for UV-200 tubes
Posts: 1,532
Threads: 242
Joined: Sep 2012
City: West Bend, Wisconsin
I'm working on an Atwater Kent model 20C 7570 and am wondering what the plate voltage to ground should be for the UV (or UX) 200 & 201 tubes? I'm measuring 27 DC Voltage on the 200 and 94 - 97 DC Voltage on the 201 tubes. The 201's seem right where they should be, as I'm using an ARBE III Battery Eliminator and the B voltage is set for 90.
Here's a link to a PDF file of the schematic:
http://www.atwaterkent.info/TechData/Dra...570sch.pdf
I had to replace both audio interstage transformers with the P-T156's available from Antique Electronic Supply. If the secondary of the audio interstage transformer's polarity is reversed or in the opposite direction of the primary, is that critical?
And for the ARBE III Battery Eliminator if interested:
http://www.arbeiii.com/
Many thanks for any help you can provide.
Greg V.
West Bend, WI
Member WARCI.org
Posts: 16,266
Threads: 566
Joined: Oct 2011
City: Jackson
State, Province, Country: NJ
What do you mean by measuring AC volts on plates?
Posts: 1,532
Threads: 242
Joined: Sep 2012
City: West Bend, Wisconsin
Sorry meant DC voltage....
Greg V.
West Bend, WI
Member WARCI.org
Posts: 599
Threads: 24
Joined: Jan 2014
City: Edmonton AB CA
The detector plate voltage should be 22.5 volts but you are close enough it should work. Do you have that detector B+ lead connected to the 22.5 volt terminal on the ARBEIII? If so you should be go.
Gregb
Posts: 1,114
Threads: 14
Joined: Feb 2013
City: Irvington, NY
UV-200 tubes operate at low plate voltages, usually from 22 to about 45 volts. These tubes contain a low concentration of argon gas, and they must operate a low enough voltage that the gas does not ionize.
Posts: 1,532
Threads: 242
Joined: Sep 2012
City: West Bend, Wisconsin
Thanks, Mondial. I was worried I wasn't getting enough voltage off of that tube (or too much, as they are hard to come by!)
Yes, GregB, I do have the detector B+ lead connected to the 22.5 volt terminal on the ARBEIII. I think I have to replace the .002 "phone condenser" yet with a .002 mfd and see if that makes a difference. But my gut feeling is it may be a reversed polarity on the secondary of the AIT. If anyone has any experience with those Antique Electronic Supply replacement AIT's, let me know.
Greg V.
West Bend, WI
Member WARCI.org
Posts: 599
Threads: 24
Joined: Jan 2014
City: Edmonton AB CA
What is the issue Greg? Is there no output? Do you have a signal tracer or a scope?
Gregb
Posts: 1,532
Threads: 242
Joined: Sep 2012
City: West Bend, Wisconsin
There's hum, and the rheostats do change the output level, but I'm not receiving any semblance of a station. The 3 coils all check out fine, and none of the rotars or stators are touching on the tuning capacitors. I just came up from the basement shop tonight and will dig out the signal tracer tomorrow night and see if I can find anything with that. I was mainly concerned I may have the green secondary wires on the new AIT's reversed and that it could be causing problems.
Greg V.
West Bend, WI
Member WARCI.org
Posts: 599
Threads: 24
Joined: Jan 2014
City: Edmonton AB CA
Try touching the grid leak with a screw driver and see if you get the some buzz in the output, that will prove that side of the set.
Gregb
Posts: 1,532
Threads: 242
Joined: Sep 2012
City: West Bend, Wisconsin
Well here's an update on what I found tonight. The audio output section is working fine, however I'm not getting a signal through the 2R section and back (RF section). When I touch the plate of the UX-201 tube in the 2R section I get no buzz only very faint change in static. The 3 coils all check out fine, both primary & secondary for continuity. The antenna connections check fine for continuity (but I get no change in sound when I touch the antenna connection lug with the set on). I'm thinking it has something to do with the tuning capacitors themselves. I know that the 1st tuning capacitor had 'fins' touching and I tried adjusting it a bit. More work tomorrow I guess. Funny how quickly 3 hours can pass when you're working in the basement on a radio 
Greg V.
West Bend, WI
Member WARCI.org
Posts: 7,294
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
I believe the 20 has wire wound resistors in series with the tuning caps to prevent oscillation. Check to see if any are open.
Terry
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
Bingo, Terry hit the nail on the head. The 20 does have wirewound resistors in series with the tuning caps, and they are probably all open.
If you haven't heard a properly restored three dialer in operation, you will be amazed at how well such a crude receiver can perform. Good luck - you will enjoy that 20 when you get it going. 
--
Ron Ramirez
Ferdinand IN
Posts: 16,266
Threads: 566
Joined: Oct 2011
City: Jackson
State, Province, Country: NJ
Just out of curiosity....not doubting the open wirewounds but....why would those open unless the oxidation does it to them? Even a shorted tuning cap in this setup in grid circuits will not do anything bad to them.....is that it? oxidation?
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
Probably. All I know is that I owned a 20C-7570 (Compact) several years ago, and all of those resistors were open. Once replaced, the set came to life and worked extremely well.
--
Ron Ramirez
Ferdinand IN
Posts: 16,266
Threads: 566
Joined: Oct 2011
City: Jackson
State, Province, Country: NJ
BTW it's a neat solution (I never dealt with battery tube radios so far) to only switch filament battery off by the Power switch. The rest do not discharge since there is no emission.
Users browsing this thread: 1 Guest(s)
|
|
Recent Posts
|
|
Philco 91 Restore Code ??
|
| Can someone tell me if my 42 tubes are connected triode or pentode in fixed or cathode bias? How could I tell by looking...dconant — 10:47 AM |
|
Philco 40-120C Restoration
|
| Hello David,
that is great news about the tubes source being local !
Sounds like you got good start on the radio .
...radiorich — 09:41 AM |
|
An attempt to remove the Field Coil from a G speaker
|
| Mike;
I've only run into a speaker with an open filed coil twice, and they were on newer speakers from the 1940s. One ...Arran — 12:48 AM |
|
An attempt to remove the Field Coil from a G speaker
|
| Arran
Yes, this is my plan for now and what do I got to lose, this is not even the speaker from this radio, but one o...morzh — 10:44 PM |
|
An attempt to remove the Field Coil from a G speaker
|
| Mike;
I would unwrap the field coil, and see if maybe there a break near one of the ends, like where the coil wire att...Arran — 10:23 PM |
|
An attempt to remove the Field Coil from a G speaker
|
| ...and this is what I did. I fed a little LT into the screwholes with a small brush, and a little on the rim next to the...morzh — 09:52 PM |
|
Philco 40-120C Restoration
|
| I combined the two 40-120C threads together as we like to keep the discussion of the same radio together. It helps with...klondike98 — 09:36 PM |
|
Philco 40-120C Weak, Distorted Ouput
|
| Just checked were I buy tubes price is four dollars. So living in Florid we have a local source for tubes. David David — 09:14 PM |
|
Philco 40-120C Weak, Distorted Ouput
|
| The higher voltage may be due to higher mains voltage. My mains run 120-125AC when the set was new mains would be 110-11...David — 09:09 PM |
|
Philco 40-120C Weak, Distorted Ouput
|
| Thank you for your reply. I pulled a speaker from a Philco 41-221 and received the same result. I used a signal tracer t...bluecap — 08:45 PM |
|
Who's Online
|
There are currently 2989 online users. [Complete List]
» 3 Member(s) | 2986 Guest(s)
|
|
|
|
 
|
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
