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1949 Motorola 5A9M
#43

Bob, this is the wrong sequence to look for problems and setup circuits.
Always start checking the signal path from the end of the circuit.
1) Connect the audio signal 400-1000 Hz to the first grid of the power amplifier - 3S4. Normal sound level in the speaker should be with an input signal level of 0.1-0.5 V
2) Connect the audio signal to the first grid of the amplifier of the first tube - 1S5. Normal sound level in the speaker should be with a signal level of 0.01-0.1 V
(Make the connection through a capacitor 0.1-0.01 nF)
If the audio part works correctly, go to the IF. Connect the signal generator to the radio through a capacitor 100-1000 pF
3) Connect the IF signal 455 (or other according to the specification of your radio) to the IF plate of the tube - 3U4. The normal sound level in the speaker should be with a signal level of 0.01-0.1 V
4) Connect the IF signal to the grid of the IF tube - 1U4. The normal sound level in the speaker should be with a signal level of 0.5 mV-5 mV (or better)
Try to adjust the IF filter T2 to the maximum signal
5) Connect the IF signal to the plate of the first tube - 1R5. The normal sound level in the speaker should be with a signal level of 0.5 mV-5 mV
Try to adjust the IF filter T1 to the maximum signal
6) Connect the IF signal to the grid of the first tube - 1R5. The normal sound level in the speaker should be with a signal level of 0.1 mV-1 mV (or better)
Try to re-adjust the IF filter T1 and T2 to the maximum signal.

And only after these 6 steps you can try to check the correct operation of the RF, adjust the RF settings and check the correct operation of the oscillator.

If you want to work, lie down and sleep, and everything will pass.


Messages In This Thread
1949 Motorola 5A9M - by klondike98 - 05-10-2025, 01:36 AM
RE: 1949 Motorola 5A9M - by Joe Rossi - 05-16-2025, 07:56 PM
RE: 1949 Motorola 5A9M - by Arran - 05-19-2025, 12:41 AM
RE: 1949 Motorola 5A9M - by Arran - 05-20-2025, 07:48 PM
RE: 1949 Motorola 5A9M - by klondike98 - 05-22-2025, 11:49 AM
RE: 1949 Motorola 5A9M - by klondike98 - 05-22-2025, 12:22 PM
RE: 1949 Motorola 5A9M - by Arran - 05-22-2025, 02:28 PM
RE: 1949 Motorola 5A9M - by GarySP - 05-22-2025, 05:46 PM
RE: 1949 Motorola 5A9M - by klondike98 - 05-22-2025, 07:40 PM
RE: 1949 Motorola 5A9M - by Arran - 05-22-2025, 10:05 PM
RE: 1949 Motorola 5A9M - by klondike98 - 05-22-2025, 11:56 PM
RE: 1949 Motorola 5A9M - by GarySP - 05-23-2025, 12:18 PM
RE: 1949 Motorola 5A9M - by MrFixr55 - 05-23-2025, 10:15 PM
RE: 1949 Motorola 5A9M - by klondike98 - 05-24-2025, 02:25 PM
RE: 1949 Motorola 5A9M - by klondike98 - 05-24-2025, 11:47 PM
RE: 1949 Motorola 5A9M - by Arran - 05-25-2025, 01:02 AM
RE: 1949 Motorola 5A9M - by radiorich - 05-25-2025, 02:04 AM
RE: 1949 Motorola 5A9M - by klondike98 - 05-25-2025, 01:02 PM
RE: 1949 Motorola 5A9M - by klondike98 - 05-25-2025, 06:39 PM
RE: 1949 Motorola 5A9M - by RodB - 05-25-2025, 08:10 PM
RE: 1949 Motorola 5A9M - by radiorich - 05-26-2025, 12:43 AM
RE: 1949 Motorola 5A9M - by klondike98 - 05-26-2025, 12:48 AM
RE: 1949 Motorola 5A9M - by Arran - 05-26-2025, 03:44 AM
RE: 1949 Motorola 5A9M - by Arran - 05-27-2025, 02:07 AM
RE: 1949 Motorola 5A9M - by klondike98 - 05-27-2025, 10:45 AM
RE: 1949 Motorola 5A9M - by klondike98 - 05-27-2025, 11:34 AM
RE: 1949 Motorola 5A9M - by RodB - 05-27-2025, 01:54 PM
RE: 1949 Motorola 5A9M - by Vlad95 - 05-27-2025, 02:14 PM
RE: 1949 Motorola 5A9M - by klondike98 - 05-27-2025, 03:00 PM
RE: 1949 Motorola 5A9M - by klondike98 - 06-05-2025, 10:45 PM
RE: 1949 Motorola 5A9M - by RodB - 06-06-2025, 11:32 AM
RE: 1949 Motorola 5A9M - by klondike98 - 06-06-2025, 07:28 PM
RE: 1949 Motorola 5A9M - by radiorich - 06-06-2025, 08:20 PM
RE: 1949 Motorola 5A9M - by MrFixr55 - 06-06-2025, 11:24 PM
RE: 1949 Motorola 5A9M - by radiorich - 06-07-2025, 12:33 AM
RE: 1949 Motorola 5A9M - by sam - 06-07-2025, 02:12 AM
RE: 1949 Motorola 5A9M - by klondike98 - 06-07-2025, 02:07 PM
RE: 1949 Motorola 5A9M - by Paul Philco322 - 06-07-2025, 02:17 PM
RE: 1949 Motorola 5A9M - by Vlad95 - 06-07-2025, 03:50 PM
RE: 1949 Motorola 5A9M - by klondike98 - 06-11-2025, 12:00 AM
RE: 1949 Motorola 5A9M - by Arran - 06-11-2025, 12:56 AM
RE: 1949 Motorola 5A9M - by klondike98 - 06-11-2025, 03:58 AM
RE: 1949 Motorola 5A9M - by Vlad95 - 06-11-2025, 12:19 PM
RE: 1949 Motorola 5A9M - by Arran - 06-11-2025, 06:18 PM
RE: 1949 Motorola 5A9M - by Vlad95 - 19 minutes ago



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