Hello petr,
I am interested to make a receiver.
But what technology can you use for hight stability frequency?
VFO,DDS?
My first receiver used a 3Mhz VFO and a IF at 11Mhz.
(I had a 137Khz 14 Mhz converter).
I had some probleme to have a narrow band pass with 5 cristals (800Hz).
For reduct audio band pass I used a MF10.
But with this receiver I couldn't survey a frequency during more hours.
The VFO stability had no perfect.
73 marc.
----- Original Message -----
From: Petr Maly <[email protected]>
To: 136 group <[email protected]>
Sent: Friday, May 12, 2000 2:34 PM
Subject: LF: Optimal width for LF?
Hello all
I am just designing a new RX for 136 kHz band. It will have IF on 1 MHz
with
high quality x-tal filter with bandwidth 200 Hz. The main selectivity will
by obtained on AF with passive filter with coils on pot cores. Till now I
used similar filter with bandwidth about 50 Hz and it seems to be still
too
wide for LF. I was about to make it new with 15 Hz width. Somebody here
mentioned 1 Hz wide filter which seems to me to be too narrow. At least,
the
filter cannot be narrower than obtainable osc stability. Can we make a
little questionnaire here? What bandwidth do you use and what is the
experience?
73, Petr, OK1FIG
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