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38-690 Code 125
#23

To check my IF is right on, I set my digital receiver to exactly TWICE the IF frequency of the set I am aligning. If the IF is 470KC, then I st the digital receiver to 940KC.

I then tune my frequency generator, set to audio modulation internal, to the IF frequency, in this case 470KC,, and connected to a short test work output antenna and carefully adjust it until I get the maximum sound output on the digital receiver. (Make sure your signal generator has THOROUGHLY WARMED UP, at least a half hour, so it won't drift !) Now you know your signal generator is putting out the proper frequency.

I then follow the manufacturers instructions for aligning the IF, or use this general method. If the radio uses a mixer/oscillator tube like a 6A8, I pull off the cap connector to the control grid, and directly feed the output of the signal generator into the control grid through a .001 MFD condenser. Set the output of the signal generator to the lowest setting that gives a clearly audible tone through the set being adjusted. I then peak the first and then the second IF transformers until I get the strongest audio signal through the speaker. You can use a voltmeter set to AC volts across the voice coil for this, or do it by ear if you have good ears. After I peak the second IF transformer, I go back to the first and adjust it again as necessary. I check back and forth a couple of times.

That's it, when both of the IF transformers, or all three if it has a two stage IF strip, are adjusted for maximum peak, you're all set.


Messages In This Thread
38-690 Code 125 - by RGK20m3 - 11-24-2021, 07:26 PM
RE: 38-690 Code 125 - by klondike98 - 11-24-2021, 08:01 PM
RE: 38-690 Code 125 - by RGK20m3 - 11-26-2021, 04:41 PM
RE: 38-690 Code 125 - by klondike98 - 11-26-2021, 05:21 PM
RE: 38-690 Code 125 - by RGK20m3 - 11-26-2021, 09:29 PM
RE: 38-690 Code 125 - by RGK20m3 - 12-02-2021, 06:35 PM
RE: 38-690 Code 125 - by morzh - 12-02-2021, 07:09 PM
RE: 38-690 Code 125 - by Ron Ramirez - 12-02-2021, 07:58 PM
RE: 38-690 Code 125 - by morzh - 12-02-2021, 08:02 PM
RE: 38-690 Code 125 - by radiorich - 12-02-2021, 09:01 PM
RE: 38-690 Code 125 - by Ron Ramirez - 12-02-2021, 10:41 PM
RGK20m3 - by RGK20m3 - 12-05-2021, 05:03 PM
RE: 38-690 Code 125 - by David - 12-05-2021, 06:19 PM
RE: 38-690 Code 125 - by klondike98 - 12-09-2021, 07:08 PM
RGK20m3 - by RGK20m3 - 12-10-2021, 01:54 PM
RE: 38-690 Code 125 - by Mondial - 12-10-2021, 05:42 PM
RE: 38-690 Code 125 - by RGK20m3 - 12-10-2021, 06:15 PM
RE: 38-690 Code 125 - by morzh - 12-10-2021, 06:27 PM
RE: 38-690 Code 125 - by Mondial - 12-10-2021, 06:40 PM
RE: 38-690 Code 125 - by mikethedruid - 12-10-2021, 07:01 PM
RGK20m3 - by RGK20m3 - 12-10-2021, 09:09 PM
RGK20m3 - by RGK20m3 - 12-11-2021, 11:14 AM
RE: 38-690 Code 125 - by Mondial - 12-11-2021, 12:58 PM
RGK20m3 - by RGK20m3 - 12-11-2021, 04:41 PM
RE: 38-690 Code 125 - by Mondial - 12-11-2021, 05:48 PM
RE: 38-690 Code 125 - by tbone - 12-12-2021, 01:27 PM
RGK20m3 - by RGK20m3 - 12-13-2021, 07:24 PM
RE: 38-690 Code 125 - by Mondial - 12-14-2021, 09:22 AM
RE: 38-690 Code 125 - by morzh - 12-14-2021, 11:40 AM
RE: 38-690 Code 125 - by Ron Ramirez - 12-14-2021, 12:40 PM
RE: 38-690 Code 125 - by RGK20m3 - 12-14-2021, 02:25 PM
RE: 38-690 Code 125 - by morzh - 12-14-2021, 02:35 PM
RE: 38-690 Code 125 - by Mondial - 12-14-2021, 03:06 PM
RE: 38-690 Code 125 - by Ron Ramirez - 12-14-2021, 03:42 PM
RGK20m3 - by RGK20m3 - 12-14-2021, 09:32 PM
RE: 38-690 Code 125 - by Ron Ramirez - 12-14-2021, 09:58 PM
RGK20m3 - by RGK20m3 - 12-15-2021, 08:01 AM
RGK20m3 - by RGK20m3 - 12-15-2021, 10:55 AM
RE: 38-690 Code 125 - by Mondial - 12-15-2021, 02:02 PM
RGK20m3 - by RGK20m3 - 12-15-2021, 04:14 PM
RE: 38-690 Code 125 - by RGK20m3 - 01-02-2022, 05:05 PM
RE: 38-690 Code 125 - by Greg - 01-02-2022, 05:42 PM
RE: 38-690 Code 125 - by Mondial - 01-02-2022, 06:59 PM
RGK20m3 - by RGK20m3 - 01-03-2022, 11:36 AM
RE: 38-690 Code 125 - by Mondial - 01-03-2022, 12:43 PM
RGK20m3 - by RGK20m3 - 01-04-2022, 08:12 AM
RE: 38-690 Code 125 - by Mondial - 01-04-2022, 11:21 AM
RE: 38-690 Code 125 - by RGK20m3 - 01-04-2022, 06:01 PM
RGK20m3 - by RGK20m3 - 01-05-2022, 11:36 AM
RE: 38-690 Code 125 - by Mondial - 01-05-2022, 12:56 PM
RGK20m3 - by RGK20m3 - 01-05-2022, 01:57 PM
RE: 38-690 Code 125 - by Mondial - 01-05-2022, 04:59 PM
RGK20m3 - by RGK20m3 - 01-06-2022, 06:39 PM
RE: 38-690 Code 125 - by Mondial - 01-07-2022, 10:44 AM
RE: 38-690 Code 125 - by RGK20m3 - 01-07-2022, 12:03 PM
RGK20m3 - by RGK20m3 - 01-07-2022, 12:32 PM
RE: 38-690 Code 125 - by Mondial - 01-07-2022, 12:49 PM
RGK20m3 - by RGK20m3 - 01-07-2022, 01:31 PM
RGK20m3 - by RGK20m3 - 01-29-2022, 12:25 PM
RE: 38-690 Code 125 - by Brad Winder - 02-02-2022, 07:30 PM
RGK20m3 - by RGK20m3 - 02-04-2022, 06:41 PM
RE: 38-690 Code 125 - by Brad Winder - 02-06-2022, 01:53 PM
RE: 38-690 Code 125 - by RGK20m3 - 02-07-2022, 10:26 AM
38-690 RF Alignment - by RGK20m3 - 12-09-2021, 01:54 PM
RE: 38-690 RF Alignment - by morzh - 12-09-2021, 03:16 PM
RE: 38-690 RF Alignment - by RGK20m3 - 12-09-2021, 03:40 PM



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