Good Evening Bruce and others,
Very good on what you are doing Bruce to get the SR40 running on 30
meters.
One comment on your 80 meter operation with the 14.318 MHz clock
with the BPF stock. The response of the QSD will only be down 6 dB
for third harmonic signals without the BPF helping out on the band
of interest. Since the stock BPF is fairly broad, I wonder if the
SWBC interference you were hearing was actually around 10.738 MHz?
If you have a moment some time to check, it would be interesting to
know.
I am sure a number of us will be quite interested in hearing about
your 30 meter efforts and results.
73,
Tony KB9YIG
--- In softrock40@..., "Bruce Beford"
<bruce.beford@v...> wrote:
I have received the 40.5Mhz crystals I ordered for use in the
SoftRock to
allow operation on 30M. It is not going to be strictly plug and
play. I
built my first Softrock with a socket for the crystal, and have
been able to
get it to run with several crystals that run at less than
the "stock" 28.224
Mhz. Was listening to 80M last night with a 14.318 Mhz xtal in
there (Rx
center freq abt 3.58 Mhz) signals were slightly down due to the
front end
filter, but it worked pretty well- Except for some 40M SWBC images.
I cannot get the 40.5Mhz crystals to fire in an unmodified SR40. I
breadboarded the oscillator cicuit from the SR40, and WAS able to
get the
crystals to work if I removed C6 and C7 (100pf). When I replaced
them with
33pf caps, I could get both the original crystal, and the 40.5Mhz
crystal to
fire up fine. However, I could not repeat this by replacing C6 and
C7 on a
SR40 circuit board. I'm not sure yet what the difference is
(between my
breadboard lash-up and the PC board, maybe other stray
capacitances) I do
plan to do some additional experimenting. Possibly my stock of
2n3904s are
better(?) The ones supplied should work at this freq ok, so I'm
not sure.
In any event, I am now sure these crystals work on the fundamental
freq of
40.5Mhz. It looks like some mods will need to be done to a board
to allow
operation at that high a freq.
I'll keep ya all posted.
73,
Bruce N1RX
