[R-390] R-388 Info

[Roy Morgan]

At 04:08 PM 2/5/04 -0700, Bud K5IUO wrote:
>I have an opportunity to obtain either a R-388 or an SP-600. Both are in
>very good condition.

Cecil,

One point that may not have been mentioned yet: the R-388 PTO's.

The R-388 PTO's can be divided into two groups: those which do not drift 
and those which do, always have and always will.  By "drift", I mean the 
"endpoint spread" increases slowly over time.  That means that it takes 
more than 10 turns of the shaft to change the PTO frequency the one 
megacycle it is intended to change.

Here are significant points about this situation:
- The only way you can know which you have is to get the radio and try it out.
- Non-drifting PTO's are not rare but you don't know which you have till 
you have it. Do not rely on any seller to tell you the truth. They may not 
know what you are talking about.
- There is no cure for a drifting PTO.  You can re-align it to bring the 
spread back to correct, but it will continue to drift.  (Some folks 
overcompensate about 2 to 3 years worth of drift and then count on doing it 
again after 4-6 years.)
- Careful overhaul of a PTO and correction of drift is not for the novice, 
but is certainly doable if you are a capable technician and take advice well.
- This situation of a drifting PTO only bothers some people, not all.
- The receiver is still very useful, and normal operating procedure 
compensates for the errors.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
roy.morgan@nist.gov --