Those filters were pretty awful................I don't remember the name of
the company name, but it started with the letter K.
They were used in the NRD-515 and in the Yaesu FRDX-400. They were filled
with some sort of foam substance that turns to a sticky jelly after many
years, causing the insertion loss of the filter to degrade. Peter Bertini
had an article in Popular Communications a few years ago on how to repair
them. I did just that for a friend's FRDX-400. You have to dismantle the
filter and clean out all of the goo with alcohol..........I used a product
called Flux-Off.
Afterwards, you have to replace the foam damping material. I used air
conditioner foam strip. Another thing about those filters....there is no
other mechanical support for the filter elements themselves. When you remove
the goo, you have the filter structure hanging by a few strands of Litz
wire. For years, I was looking for an NRD-515 until I discovered those
filter problems. I have never seen a Collins mechanical filter fail in that
manner, and I have had quite a few of those filters over the years. If any
of you ever have the problem with your JRC radios that use that filter, I
can give you advice on how to repair them.....................if you don't
feel comfortable repairing them yourself, I can repair them for you.
I did have one of those 2515 in for repair a couple of years ago, and the
unit that I repaired did not have any mechanical filters even though the
advertising hype stated that it did. It was definitely one of those slightly
oblong I.F. transformers that had the ceramic filter inside the same
structure.
For a cheap receiver, they weren't bad.
Anybody remember the transceiver that matched this unit in style? A friend
once told me that it was a Kenwood TS-510 with Allied's label.

Pete

wrote in message
ups.com...
There was a Japanese company that made a smaller version
of the Collins Mechanical fitler and I htink it looked like your
discription. Poptronics ran an article int he mid 1960s about
how to add one to your existing SW receiver. I
Terry