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

CoRadio Help
#26

Hi Mr. Big,

Read your marked up schematic. I don/t think that it makes too much difference which side of R15 that the B+ to the output stage connects to. It should probably be on the other side of R15 but 2 bigger issues:

I compared this schematic to a FADA 1000, also a 6 tube set. Amazingly, except for Screen and B+ for all tubes other than the Output, Plate, the FADA having a loop antenna vs the CoRadio having a transformer for a long line antenna, and the presence of a wave trap, the FADA 1000 is remarkably similar to the CoRadio. A link to the FADA 1000 Schematic from Nostalgia Air is below:

http://www.nostalgiaair.org/PagesByModel...005622.pdf

The wave trap may be there if this radio was popular in the Great Lakes area or other maritime areas, as believe it or not, there was long wave marine communication via Morse Code (I remember hearing this on radios as a kid in the 60s, especially on fall nights.)

The most glaring issue is the 1st RF (12SK7) Screen which should be the B+ Value of 69V that the Output tube screen and IF Plate and screen should be, instead of almost zero V Check the wiring from the 1st RF Screen to the Convertor (12SA7) Screen and B+ to the Convertor side of the 1st IF transformer. Start out by ohming it. You may have a bad connection despite your great workmanship. Reheat them/ The lack of screen voltage is likely killing the RF Amp.

The other issue is the value of coupling cap C5 between the RF Amp plate and the Convertor grid and the coupling cap for the oscillator coil. You have a "?" for their values. For the FADA 1000, they are both 100pF

Also verify that you have the Antenna coil connected to the RF Stator of the tuning cap (larger plates) instead of the Oscillator (smaller plates). This will detune the Oscillator, and there would be no input to the RF like there should be.

Hope this helps.

"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis

Best Regards, 

MrFixr55


Messages In This Thread
CoRadio Help - by mister_big77 - 01-12-2023, 10:26 PM
RE: CoRadio Help - by Radioroslyn - 01-12-2023, 10:52 PM
RE: CoRadio Help - by Radioroslyn - 01-13-2023, 10:00 AM
RE: CoRadio Help - by mister_big77 - 01-13-2023, 10:18 AM
RE: CoRadio Help - by RodB - 01-13-2023, 10:48 AM
RE: CoRadio Help - by mister_big77 - 01-13-2023, 10:49 PM
RE: CoRadio Help - by RodB - 01-14-2023, 11:06 AM
RE: CoRadio Help - by mister_big77 - 01-16-2023, 01:11 AM
RE: CoRadio Help - by MrFixr55 - 01-17-2023, 05:37 AM
RE: CoRadio Help - by mister_big77 - 01-17-2023, 10:10 AM
RE: CoRadio Help - by MrFixr55 - 01-17-2023, 05:33 PM
RE: CoRadio Help - by mister_big77 - 01-18-2023, 02:29 PM
RE: CoRadio Help - by MrFixr55 - 01-18-2023, 04:12 PM
RE: CoRadio Help - by mister_big77 - 01-19-2023, 11:14 PM
RE: CoRadio Help - by MrFixr55 - 01-20-2023, 06:55 AM
RE: CoRadio Help - by mister_big77 - 01-21-2023, 08:45 PM
RE: CoRadio Help - by MrFixr55 - 01-22-2023, 01:01 AM
RE: CoRadio Help - by mister_big77 - 01-22-2023, 02:31 AM
RE: CoRadio Help - by Arran - 01-23-2023, 06:23 AM
RE: CoRadio Help - by MrFixr55 - 01-23-2023, 07:07 AM
RE: CoRadio Help - by Arran - 01-23-2023, 08:59 PM
RE: CoRadio Help - by mister_big77 - 01-23-2023, 09:47 PM
RE: CoRadio Help - by MrFixr55 - 01-24-2023, 06:31 PM
RE: CoRadio Help - by mister_big77 - 01-24-2023, 08:30 PM
RE: CoRadio Help - by mister_big77 - 01-24-2023, 10:01 PM
RE: CoRadio Help - by MrFixr55 - 01-25-2023, 02:11 AM
RE: CoRadio Help - by mister_big77 - 01-25-2023, 11:04 AM
RE: CoRadio Help - by mister_big77 - 01-25-2023, 11:38 AM
RE: CoRadio Help - by MrFixr55 - 01-29-2023, 09:46 PM
RE: CoRadio Help - by mister_big77 - 01-29-2023, 10:56 PM
RE: CoRadio Help - by MrFixr55 - 01-30-2023, 07:06 PM
RE: CoRadio Help - by mister_big77 - 01-30-2023, 11:23 PM



Users browsing this thread: 2 Guest(s)
[-]
Recent Posts
B&K 1077B no video
Hello Tim, I would if it's a leaky Capacitor So are all 3 of those B- voltages low then ? Sincerely Richardradiorich — 01:55 AM
B&K 1077B no video
I found a schematic and think I have the problem traced down to the minus power supply. I have very low voltages that go...TV MAN — 12:41 AM
RCA 15X
I'd try replacing the bulb first and if that doesn't do it, then change the 35Z5 and see if the problem goes away.NostalgiaRadioTime — 12:28 AM
B&K 1077B no video
Hello Tim, I have that exact unit in my shop too plus a Sencore unit there are times I like one or other !!. Sincerely...radiorich — 11:07 PM
RCA 15X
Everthing goes at once, maybe it's the cold weather, I have had 2 dial strings break and no my little RCA is having dial...Paul Philco322 — 10:26 PM
Philco 91 Schematic
Hi Dan, I can't explain this specific resistor but I have seen the use of a switch to apply B+ voltage to screen gri...RodB — 09:36 PM
6TPZ and 5TPO Radio Help
I suspect it's been repaired before. And I suspect whoever repaired it, wanted to re-use old transistors' pin stubs in o...morzh — 09:24 PM
B&K 1077B no video
Thanks Rich! I'll take a look and see what he has. I know there's more modern equipment to be had, but this one I know a...TV MAN — 09:11 PM
B&K 1077B no video
Hello Tim, Here is a link to restoration of one on Phil's old radios site ! Sincerely Richard bk1077bradiorich — 09:01 PM
6TPZ and 5TPO Radio Help
I'm a little befuddled on this one. Should X5 and X4 be tied together like this?  It looks like someone added this at so...R3Sons — 07:33 PM

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

>