Hello Bernd,
someone here already used an x-tal filter at the input of RX as far as I remember. I do not know his experiencies.
Anyway, I would be thankful for such a filter, but shifted by 10 MHz, that is SSB filter on 10,137 kHz for making a transvertor.

73! Petr, OK1FIG

-----Původní zpráva-----
Od:     Bernd Neubig [SMTP:[email protected]]
Odesláno:       4. října 1999 11:37
Komu:   INTERNET:[email protected]
Předmět:        Re: LF: Receivers

de DK1AG:

I am evaluationg, if I am to design a front-end crystal filter with a
bandwidth just equal to the width of the 136 kHz LF band.
It will be a four-pole filter with an ultimate attenuation of 60 dB and a
shpae facttor of 60dB to 6dB of approximately 4 (four).
For good match at the antenna side, probably an input attenuator should be
added inf ront of it.
Attention: There is a maximum input power of 10mW allowed, this means it
must be avoided, that it is connected at any time
with the transmitter ourput.

As this needs some design efforts, and there are some cost related to it, I
want to ask the lowfer-community,
- What do you think about the idea?
- Who would be interested to purchase such a filter (expected price in the
200.-DM range)?
- What is the bestl termination impedance  ? Is 50 ohms fine or should it
be in the kilo-ohms range?
- Could it be in an enclosure with solder-pins or preferably with BNC or
UHF connectors?

Please let me know your answer either in this mail-box panel or directly to
my e-mail address
[email protected]

Bernd
DK 1 AG




P.S.: I am with Tele Quarz in Neckarbischofsheim, Germany