[AMRadio] AM filters

[Brett Gazdzinski]

Gary,
Not sure how well the CB filters would work on tube gear.

Kiwa makes a very nice 455 kHz filter module available
in any bandwidth you want (I like 5.5 KHz).
It comes in a small encapsulated module you can Velcro
onto any handy spot.
It has an op amp input, three separate filters to give
the desired bandwidth, and an op amp output.
It runs off about 5 volts to 30 volts dc, and has no
loss through the filter.

It comes with pig tail shielded wires you just tack
onto the circuit.

It works amazingly well on my home brew receiver, allowing
good fidelity, and I can listen on 7290 without
interference from people operating on 7295, as long as
they don't splatter....even very strong signals don't
come through, as long as they are clean....

You can tack one of these things on any 455 kHz IF receiver and get
mechanical filter results.
All you would likely have to do is lift a couple of parts and 
tack the wires on....

Another thing I really like is the new freq counter/digital readout
kits you can get cheap.
They pick up the LO signal and offset 455 kHz to give a direct
digital readout of the received frequency.
You don't have to hook anything up to the classic
boat anchor receiver, just get a pickup wire close to the lo
tube.
AADE makes some very nice ones, and oak hills research sells
a kit with a cabinet...just put it on top of the receiver and
have an accurate readout.
Just the thing for my SX17...its dial is marked every
100 Kc!

I don't own stock in these companies, but I am hoping if I say nice
things about them, they will send me some free samples!


 
Brett
N2DTS

 
> 
> While digging through some junk boxes I came across an old CB radio. I
> haven't looked in one in a long time but remember that some had some
> pretty nice ceramic AM filters in them. I think at 455 kc. 
> Might make a
> good AM filter for some of the old radios. May need a couple 
> of matching
> xfmrs but should work
> 
> 73
> Gary  K4FMX
> 
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