[R-390] Newbie looking for Calibration Instrument(s) feedback...

[Robert P. Meadows]

I would suggest that the guidelines of equipment in the manual for the R390
be followed... Note that a good signal generator will not be inexpensive.
More so, Does the radio actually need calibration or "alignment".
Bite the bullet and only secure good quality equipment and of course the
manuals for same.  In the long run, you only purchase good test equipment
ONCE.
R

-----Original Message-----
From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> On
Behalf Of Larry H
Sent: Sunday, March 3, 2019 9:04 PM
To: R. David Eagle <kb8nnu at yahoo.com>
Cc: R-390 Forum <r-390 at mailman.qth.net>
Subject: Re: [R-390] Newbie looking for Calibration Instrument(s)
feedback...

Dave,  All great words of wisdom, so far.

If you're going to be doing any work that requires or could benefit from
having a good signal generator, take a look at what features you will need.
I started out with the inexpensive gens and got rid of all of them.
I think you will find that the  Heathkit IG-102 you mentioned is not worth
the money and probably won't meet your needs.  I have found that a sig gen
that leaks a lot of RF (like the  Heathkit IG-102) and many others, are a
big problem and make it hard to do a good alignment.  Another factor is
stability.  You don't want it to drift.  And in a few cases, it is important
to be able to know the level of uV you are feeding into the circuit.
Although frequency accuracy is not critical, it is nice to know the
frequency closely.  Another aspect is that it should have a clean sinusoidal
signal.  You will definitely want one that has tone modulation built in.

Borrowing one for a while is a good idea.

On the R-390A alignment, I agree that most of it can be done using the
built in calibrator.   I use it quite often.  You may want to calibrate it
first, using WWV, though.  Or a calibrated counter.

You will also need a vtvm.

Regards, Larry

On Sun, Mar 3, 2019 at 4:15 AM R. David Eagle via R-390 <
r-390 at mailman.qth.net> wrote:

> Hello all,
>
> I have come to the realization that I should try to calibrate my 
> Motorola R-390a since it probably is in desperate need of it.  Reading 
> through all of the manuals, it doesn't appear to be too difficult BUT 
> I am lacking some of the necessary equipment to get it done.
> I have been looking for a decent signal generator that will work good 
> without spending a ton of money.  I have been looking around on Ebay 
> and turn up everything from the Heathkit IG-102's to some new popular 
> Chinese models.
> My question to the group - Can I get away with the Heathkits for 
> calibration or is there another popular one that gets the job done?
> Thanks again for all the help?
> Dave
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