Yes Bob,
I can see that if the Astron is grounded to its own case, ie negative
strapped instead of floating as Astron intended, it could react differently
with different rigs.
The length of DC cables, and relation to wavelengths could be a problem in
some cases. Have the DC cables you use been lengthened over the factory
supplied length? I always twist my power leads tightly to minimize ground
loop RF pick up as well. Make a twisted pair to run the DC to the rig from
the battery or Astron.
Do you use clips on the Astron connection? I do, and use gold plated ones
for fewer oxidation problems. But any clean copper battery clip should work
fine.
Another issue is that in the Scout, there is already (should be,) a ferrite
core on the B plus wires a few inches in from the polarity protection diode
by the back panel power entry, (the Molex connector). Check that the bead
is there. Check the Molex for arcing, corrosion, loss of plating, and bad
contact. Check that the Red B plus wiring is two small wires in parallel to
the front panel off on switch, with the ferrite large bead placed so the two
wires loop thru it. Check that all the solder joints in the power lead
paths are good, and that the wing nut ground stud on back is very tight to
the chassis, in fact loosen it, and make sure it has a lock washer, and
retighten the nut against it to break any accumulated oxides under that
screw and its connection to chassis. Loosen all the screws holding the PA
board to the heat sink, and retighten and the Heat sink to case, etc. On
the band modules, check the solder on the large coaxial, DC power looking
connectors on the module, as these are the RF in and out to the antenna
connector. Check the springs, and center contact pins. Unplug each of the
ends of 1/8 inch coax jumpers used several places to and from the PA, and
replug to remove any accumulated oxidation. If you have some Caig DeOxit
spray, spray those on the plug in connectors. Make sure the Copper board
edge connections on the band modules is clean, and again DeOxit is a good
improvement.
Is there any evidence of humidity darkening of solder or plated connections?
Dust? Smoke, (tobacco stains)? Clean all and this may reveal some problem
from vibration or portable use over time. I carry my Scout to Field Day
every year, and have yet to have any loose connections but it can happen to
any rig.
73,
Stuart k5KVH
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