Leonard Martin wrote:

A good"cheap" source of narrow filters
can be the lowly CB. I picked up several at the local
thrift stores for next to nothing when they are missing
the mics. I even got a couple of SSB units that had
nice, narrow ceramic filters.
Next to nothing means less then 5$.

Terry

What do you do with all those CBs?

Leonard
Leonard Martin Jun 22, 10:38 pm show options
Newsgroups: rec.radio.shortwave
From: Leonard Martin - Find messages by
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Date: Wed, 22 Jun 2005 21:38:39 -0500
Local: Wed,Jun 22 2005 10:38 pm
Subject: Panasonic RF-2200
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wrote:
willismat wrote:

Does anyone know what the specs are for the wide and narrow filters,
i.e. the bandwidth and shape factors? I love this radio but the narrow
filter doesn't seem to make very much of a difference to my ears, as
far as interference rejection goes. Has anyone ever replaced either
filter with good results, and what filter did you use? Thanks!

---------------------------------
I once checked the filters, but it was back in the early
1980s. I can remember they were both rather wide.
I thought about trying to replace them, but the tunning
wasn't fine enough and the receiver wasn't stable
enough for the effort.
It had great sound on FM and good sound quality,
in spite of the over wide fitlers, on AM an SW. I loaned
mine to a friend and it was destroyed along with her
car.
One simple mod you might want to consider is to add
a 7806 linear regulator, with a switch hidden in the
battery compartment in the little space intended for
the earphone. It was a fun radio to take on picnics
and camping. I have often thought of buying another
one, but I have "too" many radios. Or at least not
enough space to stash many more.

I think the RF200 had a "stnadard" 455KHz IF, and if
so, then scalvaged CB IF filters ought to work. The
RF2200 is not at all crowded inside. Good luck on
your quest. A good"cheap" source of narrow filters
can be the lowly CB. I picked up several at the local
thrift stores for next to nothing when they are missing
the mics. I even got a couple of SSB units that had
nice, narrow ceramic filters.
Next to nothing means less then 5$.

Garage sales are another good source. It helps if your
wife has friends who think garage sales are a Holy
mandate. I have a set deal, buy me all the CBs you find
for $5 or less. I help with their home PCs os it balances
out.

Terry

What do you do with all those CBs?

Leonard

--
"Everything that rises must converge"
--Flannery O'Connor
-------------------------------------
I have been hunting for better Murata ceramic
IF fitlers. I have several radios to upgrade.

I have converted several to "outboard" IF strips.
Buffer the 455 KHz in a SW, feed it to the modified
CB and instant better, as in more slective receiver.
And some of the better ones I fix and give/trade to
friends. The SSB ones are worth converting to 10
mtrs. Several of us have an very informal net on
10mtrs.

I like to experiment. I have a very nice sears(Uniden)
SSB that I plan on convering to 17Mtrs. I always have
more interests then time.

Murata no longer sells the really nice fitlers, so unless
one has a vender with some stashed, this is the only
way to get them. I generally get a CB a month. CBs are
full of usefull RF parts. RF Power transistors, RF chokes
etc.

But the best ceramic filters pales when compared to a even a
poor crystal filter. And good crystal filters must be heard to be
aprreciated. You can stack up to 3 simialr ceramic fitlers for
improved skirts. But crystal filters are better. And expensive.

When I get the chance I am going to replace the stock filters in
our(my wife and I each have one)DX398s.

Terry
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