[R-390] Case Comments

[Drew P.]

Perry wrote:

>For the R390 the first solution to the regulator heat
>problem is to install the SS regulator designed by
Dr. >Jerry in the HNS that has been mentioned before.

Dr. Jerry didn't design the Solid state regulator that
was the topic of that Hollow State News article.  It
was found installed in an R-390 purchased by, IIRC,
one of the Barrys who then enlisted the help of Dr.
Jerry in analyzing the regulator's circuit.  It was a
simple emitter follower type regulator using 2 NPN
darlington-connected TV horizontal output transistors
as a pass element.  The reference was a zener diode
with another zener ahead of it as a pre-regulator.  It
needs and was bolted to a large heat sink.

Changing to the SS regulator would eliminate some heat
otherwise generated by the tube heaters, but there
would still be considerable heat due to the voltage
drop in the pass element.  The SS regulator would be
best located outside the radio with an umbilical.

On heat generation in the R-390A, Perry went on to
say:

>People have reported putting spacers under the audio
>module because of the heat generated by the dropping
>resistors in the closed space.  Why no one has
>suggested putting the resistors on top and the filter
>caps inside the audio module is a  mystery to me.

I made that suggestion in this forum about 5 years ago
and it was met with the same type of indifference that
sugggestions of any other type of hack-em-up mod would
receive here.  I never actually tried it in my
R-390-A.  How many of us here went so far as to
attempt the kielbasa-for-ballastube substitution?  


Drew




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