I mix 10 MHz VXO with 8863 kHz XO. Stability looks sufficient, all this
gear will be placed in closed robust alluminium box which will be surrounded
by polystyrene casing to provide temperature isolation. I wanted to have no
tuning step to be able to use extremely narrow filters.
73, Petr, OK1FIG
----- Original Message -----
From: mv tsi <[email protected]>
To: <[email protected]>
Sent: Monday, May 15, 2000 1:32 PM
Subject: LF: Re: Optimal width for LF?
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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