[R-390] Filter Options II

[Les Locklear]

Here are a couple of articles on using the Kiwa filter modules on various 
types (tube and solid state) receivers.

http://kiwa.com/errvw.html

http://kiwa.com/goodwin.htm

Les

-----Original Message----- 
From: djed1 at aol.com
Sent: Monday, February 18, 2013 8:17 AM
To: ham at kb8tq.com ; r-390 at mailman.qth.net
Subject: Re: [R-390] Filter Options II

Probably a lot of filters out there- I have a set of spare filters stashed 
away.  What I don 't know is whether they are deteriorating as they sit in 
the box.  My R-390A has been in my possession for 30 years and has  seen 
light use all that time.  I hope that the deterioration of the foam in the 
filters is somewhat related to the operating temperature.
Ed  W2EMN







-----Original Message-----
From: Bob Camp <ham at kb8tq.com>
To: r-390 at mailman.qth.net Group <r-390 at mailman.qth.net>
Sent: Sun, Feb 17, 2013 10:14 pm
Subject: Re: [R-390] Filter Options II


Hi

I keep coming back to another option:

How many IF modules are there still out there? The world was awash in them a
while back. I have a suspicion there are many more out there than one might
think.

Bob

On Feb 17, 2013, at 5:00 PM, Perry Sandeen <sandeenpa at yahoo.com> wrote:

> List,
>
> Wrote: With the exception of watch crystals, the whole industry of sub 1 
> MHz
crystals is pretty much a thing of the past. Yes, there are a couple of 
people
who will make you this or that. You better have deep pockets to get them
interested in whatever you need done. Yes, one of them is a buddy, but that 
only
goes just so far.
>
> Yea verily.
>
> My take of the group’s replies is that:
>
> 1. Crystal filters are out of the question unless one does and up
converter/down converter to use some of the commercial filters used in the 
rice
box radios.  Probably a real PITA.
>
> 2.  While ceramic filters can be used, the supply is probably extremely
limited, even worse that getting a original Collins replacement filter for 
the
“A”.
>
> 3.  Use the Lankford roofing filter mod and stick to a 6 KHz or less
bandwidth. For a $100 or so it is probably the most cost/time effective
solution.
>
> 4.  Convert your “A” to a R-725 and selling your remaining good filters on
epay to help offset the conversion cost.  Takes a lot of time and patience 
to
convert the I.F. to 6 volt filaments. (Yes Tisha, I have 3 to do when I get
a-round-to-it.)
>
> 5.  Something microprocessor based would be too complex for the vast 
> majority
of us.
>
> Regards,
>
> Perrier
>
>
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