[R-1051] sequence for osc checking

[Cecil Acuff]

Hi John and group,

        Sorry for the delay in answering,  I am in the process of trying to
relocate the computer stuff to a new area of the house.

The first thing I do is make sure that the relay that attenuates the
incoming signal when tuning is ok.  They can develop intermittent problems.
I have found many that have been bypassed by tying the center conductor of
the coax cables together on one of the two posts they are soldered to.  I
haven't found the relays to be much of a problem.

The first real troubleshooting I do is to check the power supply for proper
voltages out.  You are looking for the regulated +20vdc, it should be right
on and is adjustable on the power supply board.  The -30 vdc, +28vdc and
+110vdc should also be checked.  Loss of one supply could cause the radio to
act as you describe.

The next thing to check is the Frequency Standard.  It is the heart of the
radio...if it is sick or off freq. the whole radio acts sick.  You need to
check the 5 mc osc. output.  It is easy because it is plumbed out to a BNC
connector on the rear of the radio.  It should vary only a couple tenths of
a cycle in 24 hours once up to temp.  The 10 mc, 1mc and 500cps outputs also
need to be checked.  They can be tested by probing the RF connectors that
are mounted in the chassis feeding the Sixpak module.  You are interested in
proper frequency, level and symmetry of the waveform.  If they are ok the
next step is to check the signal levels and frequencies that are going into
the RF Translator.

You will need the "Overall Servicing Diagram"  and an extender cable that
will allow you to get to the test points in the Translator while the radio
is powered up.  You are looking for the inputs to the Translator from the
1&10kc synthesizer, the 500 or 100cps synthesizer (plain or "B" and up
radios respectively) and the 1mc synthesizer modules.  If one of these are
missing you will need to back up to the source for the synthesizer in
question.  It could be in the Spectrum Generator or an output from one of
the other synthesizers that provide a signal to the synthesizer in question.
If the synthesizer in question has all the proper inputs then you have
probably found the culprit.

It gets confusing but if you make notes as you make the checks you will
minimize having to recheck things you have already checked.

The spectrum generator uses several multiplier circuits to achieve the
outputs needed.  The are all adjustable and if mis-aligned can cause lots of
problems.

As you can see you will need a good scope, preferably one that has on screen
digital displays for time and/or frequency.  You will also need an RMS
voltmeter, a good copy of the manual and an extender cable for one of the
hybrid DB connectors.  (the largest connector)

Also a good dose of patience is a plus!

These are tough radio's to work on when they are sick...nothing is easy to
get to! The Sixpak module is the most complex in the radio!

Hope this helps...

73..

Cecil Acuff

The R1051 Shop.
www.r1051shop.com (new page coming soon)