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

38-15 Restoration
#31

Well, the reason was as I expected it a stupid one: when I reconnected the tuning cap, I soldered back the pentagrid's cap but forgot the antenna coil.
I noticed that when I connected the generator - it was coming through but extremely weak....

Well, it sings where it's supposed to...mostly, and the alignment seems to be where it should be, with a single problem: at the Short Wave band when I use the generator the beep disappears right about between 8MHz and 7.5MHz. I knew the tuning cap is OK as at the BC band it works in the same position.

So I theorized the oscillator is not oscillating starting about 7.5MHz and connected the scope to the IF coil output...I was correct, the oscillation sharply decreases at about 8.5 and fully disappears after 8MHz.

6A7 is my pentagrid. Since it oscillates otherwise I think the coils are OK (I think I checked the continuity but will check again just for s..ts and goggles).
The pentagrid was the single weaker tube: the pentode section is supposed to test at about 1000uMho and it gives me about 700. Although I don't see how that can kill the oscillation.

Have to see if there are old micas there...not sure they can do that though.

Anyone has experience with something like that - part of the band is bad? The other part is OK and is very well aligned.

Oh...hadn't checked the voltages yet. Have to do that to see if the regimes are OK.


Messages In This Thread
38-15 Restoration - by morzh - 02-02-2013, 05:59 PM
RE: 38-15 Repair - by Ron Ramirez - 02-02-2013, 10:11 PM
RE: 38-15 Repair - by morzh - 02-02-2013, 10:22 PM
RE: 38-15 Repair - by morzh - 02-02-2013, 10:32 PM
RE: 38-15 Repair - by Paul Philco322 - 02-02-2013, 11:21 PM
RE: 38-15 Repair - by morzh - 02-02-2013, 11:25 PM
RE: 38-15 Repair - by Ron Ramirez - 02-02-2013, 11:49 PM
RE: 38-15 Repair - by morzh - 02-02-2013, 11:54 PM
RE: 38-15 Repair - by Arran - 02-03-2013, 09:31 PM
RE: 38-15 Repair - by morzh - 02-03-2013, 10:17 PM
RE: 38-15 Repair - by morzh - 02-09-2013, 02:28 PM
RE: 38-15 Repair - by morzh - 04-06-2013, 04:54 PM
RE: 38-15 Repair - by codefox1 - 04-07-2013, 10:33 AM
RE: 38-15 Repair - by morzh - 04-07-2013, 10:50 AM
RE: 38-15 Repair - by morzh - 04-07-2013, 04:58 PM
RE: 38-15 Repair - by morzh - 04-07-2013, 05:04 PM
RE: 38-15 Repair - by morzh - 04-07-2013, 06:27 PM
RE: 38-15 Repair - by morzh - 04-07-2013, 07:49 PM
RE: 38-15 Restoration - by Ron Ramirez - 04-09-2013, 08:13 PM
RE: 38-15 Restoration - by morzh - 04-09-2013, 08:36 PM
RE: 38-15 Restoration - by morzh - 04-09-2013, 08:59 PM
RE: 38-15 Restoration - by morzh - 04-10-2013, 10:24 PM
RE: 38-15 Restoration - by Ron Ramirez - 04-11-2013, 05:32 AM
RE: 38-15 Restoration - by morzh - 04-11-2013, 11:16 AM
RE: 38-15 Restoration - by morzh - 04-20-2013, 09:08 PM
RE: 38-15 Restoration - by Arran - 04-20-2013, 09:30 PM
RE: 38-15 Restoration - by morzh - 04-20-2013, 09:41 PM
RE: 38-15 Restoration - by morzh - 04-21-2013, 06:22 PM
RE: 38-15 Restoration - by morzh - 04-22-2013, 05:24 PM
RE: 38-15 Restoration - by morzh - 04-24-2013, 11:27 PM
RE: 38-15 Restoration - by Ron Ramirez - 04-25-2013, 09:21 AM
RE: 38-15 Restoration - by 7estatdef - 04-25-2013, 12:02 PM
RE: 38-15 Restoration - by morzh - 04-26-2013, 12:41 AM
RE: 38-15 Restoration - by BrendaAnnD - 04-26-2013, 02:32 AM
RE: 38-15 Restoration - by morzh - 04-26-2013, 11:46 AM
RE: 38-15 Restoration - by Ron Ramirez - 04-26-2013, 11:48 AM
RE: 38-15 Restoration - by morzh - 04-26-2013, 11:54 AM
RE: 38-15 Restoration - by morzh - 04-26-2013, 11:56 AM
RE: 38-15 Restoration - by morzh - 04-26-2013, 06:20 PM
RE: 38-15 Restoration - by morzh - 04-27-2013, 10:57 AM
RE: 38-15 Restoration - by morzh - 05-01-2013, 09:21 PM
RE: 38-15 Restoration - by Mondial - 05-01-2013, 10:06 PM
RE: 38-15 Restoration - by morzh - 05-01-2013, 10:21 PM
RE: 38-15 Restoration - by morzh - 05-02-2013, 06:16 PM
RE: 38-15 Restoration - by morzh - 05-03-2013, 11:48 PM
RE: 38-15 Restoration - by BrendaAnnD - 05-04-2013, 01:12 AM
RE: 38-15 Restoration - by morzh - 05-04-2013, 12:37 PM
RE: 38-15 Restoration - by morzh - 05-07-2013, 10:59 PM
RE: 38-15 Restoration - by morzh - 05-12-2013, 09:51 PM
RE: 38-15 Restoration - by Arran - 05-12-2013, 11:03 PM
RE: 38-15 Restoration - by morzh - 05-12-2013, 11:16 PM
RE: 38-15 Restoration - by Arran - 05-13-2013, 12:18 AM
RE: 38-15 Restoration - by morzh - 05-13-2013, 09:13 AM
RE: 38-15 Restoration - by morzh - 05-13-2013, 09:17 PM
RE: 38-15 Restoration - by morzh - 05-14-2013, 11:06 PM
RE: 38-15 Restoration - by morzh - 05-15-2013, 10:45 PM
RE: 38-15 Restoration - by morzh - 05-15-2013, 10:50 PM
RE: 38-15 Restoration - by morzh - 05-17-2013, 11:55 AM
RE: 38-15 Restoration - by Mondial - 05-17-2013, 02:59 PM
RE: 38-15 Restoration - by morzh - 05-17-2013, 04:25 PM
RE: 38-15 Restoration - by morzh - 05-17-2013, 10:54 PM
RE: A 38-15 - by Paul Philco322 - 02-02-2013, 06:10 PM
RE: A 38-15 - by morzh - 02-02-2013, 09:09 PM
RE: A 38-15 - by morzh - 02-02-2013, 09:39 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Need to purchase some accessories for restoration of my Old Philco Radio
Hi Paulo, Welcome to the Philco Phorum. I can see why you want to find good reproduction parts. That is a bea...MrFixr55 — 11:10 PM
HiFi (Chifi) tube amp build - but my own design.
Tim, I have some bakelite sockets in my work shop that I can dig up. I believe quite a few are NOS. I will take photo...RodB — 10:03 PM
Philco 610B oscillator wiring
> The cathode as noted is wired directly to the ground side of the heater filament for that tube, not to the #17 and ...Radioroslyn — 08:12 PM
HiFi (Chifi) tube amp build - but my own design.
Tim; I noticed your post a little late, but I would take one of the junk sockets and try to break a chunk out of it wi...Arran — 08:07 PM
Need to purchase some accessories for restoration of my Old Philco Radio
Here is a list of resources found in our online library that you might find useful. Mike's Gobs of Knobs email addres...klondike98 — 01:46 PM
First Radio restoration
Hi Tubeman, Welcome to the Philco Phorum.  Phamily Phriendly Pfun with Phine Pholks Phull of Philco Phacts. (See a p...MrFixr55 — 12:33 PM
First Radio restoration
You could post in the WANTED ADs section here on the Phorum and see if anyone has an RF generator that they want to sell...klondike98 — 11:55 AM
Zenith H725
Good ideas, thank you Arrange and Rich. I have the adhesive aluminum foil already and can try that immediately. More ...EdHolland — 10:18 AM
Graphics for majestic 1050 dial glass.
Murf; I found this thread on the ARF, the first photo has a pretty good view of the dial glass. Regards ArranArran — 01:12 AM
Zenith H725
hello Ed, how about that speacial tape used for ducting it's like foil or how about thin piece of aluminum roof flash...radiorich — 12:19 AM

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

>