[R-390] Calibrator tone every 90 Khz

[Michael Murphy]

Hi Harold,

Perhaps a Motorola feature? Did you rock C310 the crystal frequency trimmer
to try and zero her back in? Do you run out of adjustment?

The crystal oven could have failed and cooked the crystal. Of course, it
could just be a bad crystal. Most likely, the crystal has aged badly and
drifted down in frequency.

Do you have a counter with a 10X probe that you can put on the crystal pins
(octal pins 2 or 8 after removing the oven cover) to check for 100 kc? Do
you have an old 100 kc crystal that you can plug in to the octal socket
between pins 2 and 8?

Next try swapping out the tubes in the calibrator.

It also could be a cap or resistor failure in the circuit. This means
pulling the RF Deck - much fun!

My R390A calibrator had poor output - you could barely make it out on most
cal points.
I pulled my RF deck a couple of months ago when I was doing my general
re-cap exercisce and replaced quite a few capacitors. I can report that
several of the resistors in the calibrator, especially the plate resistors
on the multivibrator were cooked and way off in value. I replaced R221, R224
and R226 with 1Watt flameproofs.

Wishes for a much happier calibrator

Mike WB2UID

----- Original Message -----
From: <hdalexander at att.net>
To: "R-390" <R-390 at mailman.qth.net>
Sent: Thursday, July 08, 2004 12:22 AM
Subject: [R-390] Calibrator tone every 90 Khz


> Hi All
>
> I have a Motorola R-390(non-A). The calibrator makes a tone approximately
every 90 Khz., not every 100 Khz.. For example: 14000, 14090, 14180,14270,
14360. Do any of you have any words of wisdom for me? Thank you in advance
for any help.
>
> Harold Alexander
> Modesto, CA
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