|
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
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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]
|
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
_._
toggle quoted message
Show quoted text
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
|
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
toggle quoted message
Show quoted text
--- In BITX20@..., 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
[Non-text portions of this message have been removed]
[Non-text portions of this message have been removed]
|
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
_._
toggle quoted message
Show quoted text
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
|
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.
toggle quoted message
Show quoted text
--- In BITX20@..., arv <arvid.evans@...> 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@... <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
[Non-text portions of this message have been removed]
[Non-text portions of this message have been removed]
|
Jerry
Something really strange going on there. Do you have a different
crystal in the
same frequency range that could be substituted into the circuit?
Alternatively you might be able to build up a similar oscillator using
ugly-style
on a scrap of PCB and verify that your crystal can, or cannot, be
tuned. If you
don't reuse any L or C from the original circuit that would tell you if
the problem
is the crystal or one of the other components.
Since the IF filter crystals are the same frequency, it might be
possible to try one
of them in place of your present BFO crystal. Might prove something, or
might
not...?
The LC tuning mechanism can be changed from parallel to series, or
vice-versa,
to see if that makes a difference. My preference has always been to put
the L in
series with the C, and that in series with the crystal, but I have seen
it with the LC
network being parallel and that in series with the crystal. Both ways
usually seem
to work.
Arv
_._
toggle quoted message
Show quoted text
On 06/28/2013 10:49 AM, jerryk5lru wrote:
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@... <mailto:BITX20%40yahoogroups.com>, arv
<arvid.evans@...> 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@... <mailto:BITX20%40yahoogroups.com>
<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
|
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] > 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]
|
I'd really be suspicious of having a wrong value capacitor in the BFO circuit. Almost anything else would cause a small difference, not the big change you have.
Leonard
toggle quoted message
Show quoted text
--- 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]
|
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
toggle quoted message
Show quoted text
--- 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]
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I meant to say the 15pf in parallel
with the variable cap. I put in a 22pf cap. I tested the 15pf and discovered it is a 150pf. It is one of those little plastic NPO's with the markings illegible. It was in a plastic bag marked 15pf. Leonard your suspicions were right.No wonder I couldn't get any adjustment. I wonder now if I go back from 22pf to 15pf if I will get more adjustment. 2KC's is not very much. Jerry K5LRU
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--- In BITX20@..., "jerryk5lru" <jerry@...> wrote:
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
--- 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
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Did you test your crystal in a stand alone oscillator ?
The only way to see what the original Freq is .
The circuit ( bfo ) is maybe oscillating by himself stronger then the signal from your crystal . In that case the crystal no longer act as but only as a self with a C.
Marc
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Leonard
F8VOA