R2001A Squelch adjustment

[cahighwayman22]

So my R2001A is now almost working, got an issue with the squelch setting. Seems like I have to turn the squelch all the way counterclockwise to hear the unit receive weak signals. The squelch opens fine on strong signals, when the front panel potentiometer is set at the 9 o clock position.

The A11 RF module is okay, as the receive sensitivity, and generate functions are working normally. My dad thinks the 455KHz IF, or FM detector needs alignment.

The book doesn't give a well description on aligning the IF section.

Anyone have any thoughts?

-Trevor

[cahighwayman22]

Bump

[crash]

I had to replace all the electrolytic caps in my R2001C.

You might want to check yours, but I had to pull them to see the leakage on the bottom.

The AGC/squelch circuit uses a DC voltage from an AM detector and a DC voltage from the
squelch set pot. The voltages are compared and when the comparator trips, it sets the signal
present line. If the voltage is loaded down due to leaky caps, who knows what the unit will do.

The AGC/squelch circuit is on the receiver board A4 on my C unit, I don't know if it is the same
with the A. I suspect the circuit is the same tho, as it is a circuit I have seen used on other radios.

When I replaced my caps, I also changed them on the LV power supply, as well as all the other boards.
The only module I have not changed the caps on, is the HV power supply.
Fortunately, the PC boards didn't have any corrosion from the leakage as I have seen on other equipment.

Good luck!

[cahighwayman22]

The receiver modules are the same for both units. I have a spare module from a C unit that has a shorted LV power supply ( replaced all of the caps, and quite a few componants, and pretty much gave up). I did swap them, but it made no difference.

I did recap the power supply on the A model. I'll look at the receiver board again and see if I can find anything.