[R-390] Soft-Starting and R-390/URR

Barry Scott 72volkswagon at gmail.com
Thu Sep 26 22:29:31 EDT 2024


I have a small aluminum box I built long ago that has an IEC male
connector, a three-prong power outlet, a fuse, and a CL-80 inrush current
limiter.

I've been leaving the R-390/URR powered through my homebrew metered
autotransformer that measures both voltage and amperage.  When I have it
connected that way, at power, the 5A meter is pretty much slammed to the
right for just a brief moment (expected).

As a test, I incorporated the CL-80 between the autotransformer and the
radio.  I was somewhat surprised at the difference that makes.  The meter
now only jumps to around 3A and then settles at the normal current demand.

I've used these before but never where I could do a before/after
comparison.  It was pretty revealing.  The box gets a little warm after a
while (30 minutes or so) but not all that bad.  The CL-80 should probably
have more air around it or the box could have a decent heat-sink but,
overall, I think it's okay as-is.

Still having a lot of fun with the "new" radio.  It sure sounds better
after getting the RF, variable IFs, and the IF aligned.

Thanks,
Barry - N4BUQ


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