Michael Black wrote:
ken scharf ) writes:
Pete KE9OA wrote:
The only mechanical filters that I have seen problems with are the Japanese
units that you find in the JRC receivers. There is some sort of foam that
deteriorates over the years. I haven't seen a problem with Collins filters.
I have an old Collins filter made for the R390 series receivers. It is
a cylindrical filter with two pins at each end for connections. I can
hear something rattling around inside this filter as I tilt it from side
to side. Has something deteriorated inside this filter or is this
normal? A later rectangular Collins filter does NOT make this noise.

I don't think a noise is normal.

But, it's always possible that they can be dropped.

The issue Pete is talking about is that those Japanese filters were
made with different materials, and they decay with time.

Michael VE2BVW

My filter has never left the original Collins packing (heavy cotton
lining in a large cardboard box) since I got it at a hamfest years ago
(for a project that never happened). I remember the filter seemed ok
when I bought it, and it was NEVER dropped (by me anyway). Years later
when I found it while packing for a move I noticed it developed this
sound when handled.

Well, I think I'm just going to go with a modern, portable SWL receiver
for now. There are several very interesting models that are quite
cheap. New prices are about $150 for the newest and best of them.

I appreciate all the input and encouragement. I built my first
'Manhatten' constructed circuit this week - a VFO for the BITX20
transceiver. The good news it oscillates, the bad news is not at the
right frequency or the right spread but I've got an online buddy
helping me out and if nothing, I got off of dead center. I'm just
excited that it worked at all - AND - that I understand most of it and
how it works. I'm pretty sure I will understand it all before I'm
finished.

If you're intersted the radios I'm looking at are the Eton E5, Sony
ICF-SW7600G & GR, Degen/Kaito DE-1103 and a couple of other oddballs.
Hopefully I can snag one off of eBay.

Thanks again.

Dan KB9JLO