Jerry K5LRU
That indicates that your BFO oscillator should be tunable. Next step would
be to check capacitor and inductor values to make it tune across the crystal
frequency. You can change the inductor to a toroid core (T37-6 should work)
and adjust the turns until you get it to the right frequency. Toroid
calculator
located at <> can help with that task.
Arv K7HKL
_._
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On 06/27/2013 10:59 PM, jerryk5lru wrote:
The crystal brand is KDS. I took your advice Arv and shorted the
crystal out and the frequency tuned from 8104. MHz to 8239. Mhz 105 KC
range. But way lower than the 9995. Mhz area. Jerry K5LRU
--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, arv
<arvid.evans@...> wrote:
Jerry K5LRU
The LC network in series with the crystal (including series-C of the two
feedback divider caps) needs to tune to the crystal frequency. Tuning
this resonant network a bit above to a bit below the crystal frequency
is what pulls it up or down.
I would check the resonance components associated with the crystal.
You might be able to get an idea of what is going on by temporarily
soldering a very short wire across the crystal to take it
out-of-circuit.
Then check the oscillator frequency. It should be close to the crystal
frequency with the crystal shorted. Tuning range with the crystal
shorted will be more than with the crystal in-circuit, but this will
tell
you if your tunable network really is tunable.
Arv K7HKL
_._
On 06/27/2013 12:02 PM, Paul Daulton wrote:
What type and brand of xtals are you using?
Paul k5wms
Quoting jerryk5lru :
This is a Bitx20 Version 3. I'm almost done with it. The receiver
receives good, the VFO bandwidth is between 14,000. and 14,450. The
exciter produces a signal of 500mv and the PA kicks that up to
around 4
volts. When trying to tune the BFO and the carrier balance is where I
have the problem. My frequency is 9995.31 mhz at the emitter of Q9.
Here is where the problem starts. Leonards instructions say I should
have 15kc adjustment. But all I have is about 3 hertz, not kilohertz
with the 22pf trimmer. So when I try to adjust the carrier balance, in
transmit, 7 db down the filter skirt, I have no adjustment. The
carrier
balance is .321mv on the low side and .634mv on the high side. It
nulls
out in the middle of the pot. This is why I think I'm not getting
enough drive. Any thoughts? Thanks, Jerry K5LRU
Paul Daulton K5WMS
beacon WMS 185.302 khz qrss30/slow 24/7
Jacksonville,Ar 72076
em34wu
