I think I found the problem, or at least part of it. I changed the 15pf capacitor in series with the variable cap and replaced it with a 22pf. I now have almost 2KC of tuning. I can actually hear changes when I adjust the variable cap. But it still doesn't seem like it is enough. I'll try and tune the carrior modulator and see how that goes. Jerry K5LRU
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--- In BITX20@..., "Paul Daulton" <k5wms@...> wrote:
Jerry I wonder if your xtal\s came with thie kit or you sourced them
some where else? Try swaping an xtal from filter with the bfo xtal.
Could the xtals be series resonant type? rather than parralell types?
Paul k5wms
Quoting jerryk5lru :
Arvid
I wound a 37-6 with fifty turns as per the calculator, worse. I shorted
the crystal and found I had moved lower to 6190. from the 8200. But
still had the 135 KC tunable range with the crystal shorted. I played
with the coil until I got it to the 9995. range with the crystal
shorted and still had 135 KC tuning range, when I removed the short it
went back to just a 5HZ tuning range.
--- In BITX20@..., arv wrote:
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
_._
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@... , arv > > 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 > > > >
[Non-text portions of this message have been removed] > > > >
[Non-text portions of this message
have been removed] > > > > > > > > > > > [Non-text portions of this
message have been removed] > Paul Daulton K5WMS beacon WMS 185.302 khz
qrss30/slow 24/7 Jacksonville,Ar 72076 em34wu
[Non-text portions of this message have been removed]
