开云体育

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]

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]

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 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]

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

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]

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

Why can't you take the 12.6 volts supply for the 20a and at about 10
watts out the current draw is about 2 amps. Subtract about 300mas no
mod current and you get 12.6 x 1.7 = 21.42 watts. If you figure 50%
efficency you would have about 10.5 watts out.

If that doesn't work, let me know. It makes sense to me.
Leonard

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, arv
<arvid.evans@...> wrote:

Arnab - VU2BPW

This sometimes confuses me as well.

It seems that the key is in impedance relative to voltage and

current. If

we lower the impedance the current will increase and voltage will stay
the same.

In case of a push-pull output stage like the BITX20A, the output
transformer has a turns arrangement of 6 turns on the primary and 8

turns

on the secondary. Since the antenna presents a 50 ohm load and the
antenna LPF is designed for 50 ohms on each end, the impedance seen
by the MOSFETs would be lower than 50 ohms. This allows the current to
be more than would be the case if the MOSFETs were operating into a 50
ohm load.

In the original BITX and in the BITX Version-3, the final amplifier

is a

single
MOSFET operating into an autotransformer arrangement. This lowers the
impedance seen by the MOSFET, and allows higher current and higher
power than would be the case if the MOSFET were operating into a 50 ohm
load.

If we assume that a lower load impedance at the output device causes

more

current to flow, then increasing power is a matter of changing the

output

impedance transformation so that more current can flow and still

maintain

a 50 ohm match to the antenna. If the voltage remains the same, then the
impedance will be lower and power will be higher. Of course there

are some

limitations to this idea. Resistance in transformer windings, core
saturation
in transformers, on-resistance in MOSFETs, and non-linearity in MOSFET
devices all conspire to work against us in low voltage and high power
situations.

Arv - K7HKL
_._


On 06/20/2013 11:08 AM, arnab bhaumik wrote:

hi arv,

i am still a little bit confused. with 12volt and a single irf510
based design, how much rf power can we get??? 12volt rf across 50 ohm
load, so my calculation goes

12v * .707 = 8.484 rms

rms square = 8.484 * 8.484 = 71.978

rms square / 50 = 71.978/50 = 1.43watt.

it seems with the math formula we can get max 1.43 watt from 12volt
with single irf. thats why people increase the linear voltage to
24volt . so that they can get rf of around 5.75watt.

please clarify this.

arnab/vu2bpw

ps - this is the reason i tried irf push pull to get 5watt with

12volt

supply voltage. (but failed)

________________________________
From: arv <arvid.evans@... <mailto:arvid.evans%40gmail.com>>
To: BITX20@... <mailto:BITX20%40yahoogroups.com>

<mailto:BITX20%40yahoogroups.com>

Sent: Thursday, 20 June 2013 9:52 PM
Subject: Re: [BITX20] More Power Out From Bitx 20/3?



Rob

I think that it may take more than just increasing voltage to the

output

MOSFET. If you change the voltage the current will change and

impedances

involved will change. That would seem to require that the output
transformer
would then need to be re-designed for the new impedance in order

to match

the output LPF and antenna impedance.

Arv - K7HKL
_._

On 06/20/2013 07:43 AM, rob_kay14758 wrote:

Bitx is built and seems to be working o.k. on 20M,running on

external

13v supply. If i increased the voltage on the pa transistor only to
say 25v would we see much of an increase in power?
This circuit also looked interesting as an add on..........

Any thoughts....
Thanks
Rob

Arnab - VU2BPW

This sometimes confuses me as well.

It seems that the key is in impedance relative to voltage and current. If
we lower the impedance the current will increase and voltage will stay
the same.

In case of a push-pull output stage like the BITX20A, the output
transformer has a turns arrangement of 6 turns on the primary and 8 turns
on the secondary. Since the antenna presents a 50 ohm load and the
antenna LPF is designed for 50 ohms on each end, the impedance seen
by the MOSFETs would be lower than 50 ohms. This allows the current to
be more than would be the case if the MOSFETs were operating into a 50
ohm load.

In the original BITX and in the BITX Version-3, the final amplifier is a
single
MOSFET operating into an autotransformer arrangement. This lowers the
impedance seen by the MOSFET, and allows higher current and higher
power than would be the case if the MOSFET were operating into a 50 ohm
load.

If we assume that a lower load impedance at the output device causes more
current to flow, then increasing power is a matter of changing the output
impedance transformation so that more current can flow and still maintain
a 50 ohm match to the antenna. If the voltage remains the same, then the
impedance will be lower and power will be higher. Of course there are some
limitations to this idea. Resistance in transformer windings, core
saturation
in transformers, on-resistance in MOSFETs, and non-linearity in MOSFET
devices all conspire to work against us in low voltage and high power
situations.

Arv - K7HKL
_._


On 06/20/2013 11:08 AM, arnab bhaumik wrote:

hi arv,

i am still a little bit confused. with 12volt and a single irf510
based design, how much rf power can we get??? 12volt rf across 50 ohm
load, so my calculation goes

12v * .707 = 8.484 rms

rms square = 8.484 * 8.484 = 71.978

rms square / 50 = 71.978/50 = 1.43watt.

it seems with the math formula we can get max 1.43 watt from 12volt
with single irf. thats why people increase the linear voltage to
24volt . so that they can get rf of around 5.75watt.

please clarify this.

arnab/vu2bpw

ps - this is the reason i tried irf push pull to get 5watt with 12volt
supply voltage. (but failed)

________________________________
From: arv <arvid.evans@... <mailto:arvid.evans%40gmail.com>>
To: BITX20@... <mailto:BITX20%40yahoogroups.com>
Sent: Thursday, 20 June 2013 9:52 PM
Subject: Re: [BITX20] More Power Out From Bitx 20/3?



Rob

I think that it may take more than just increasing voltage to the output
MOSFET. If you change the voltage the current will change and impedances
involved will change. That would seem to require that the output
transformer
would then need to be re-designed for the new impedance in order to match
the output LPF and antenna impedance.

Arv - K7HKL
_._

On 06/20/2013 07:43 AM, rob_kay14758 wrote:

Bitx is built and seems to be working o.k. on 20M,running on external
13v supply. If i increased the voltage on the pa transistor only to
say 25v would we see much of an increase in power?
This circuit also looked interesting as an add on..........

Any thoughts....
Thanks
Rob

[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]

Bitx is built and seems to be working o.k. on 20M,running on external
13v supply. If i increased the voltage on the pa transistor only to
say 25v would we see much of an increase in power?
This circuit also looked interesting as an add on..........

Any thoughts....
Thanks
Rob

Dave MW0PRI

45 to 50 mv is the best level. If using a signal generator input you will
need to disconnect R-92 so that it is not trying to pull your signal
generator output to +12 volts.

I don't remember anybody publishing results from using the two-tone
method for BITX20A alignment. Others on this group would probably
be interested in how you did it, and in how well it worked.

Arv K7HKL
_._

On 06/16/2013 02:31 PM, DaveP wrote:

Dear All,

I am still messing with final alignment of my bitx20a. Having read
advice, and given I quite like building things, I have just built a
simple "tone tone oscillator" kit to help set up the bitx20a. The kit
has an "optional" resistor to let me reduce output levels. Without it,
the maximum p-p voltage is about 450mv, but I can reduce that lots
with a pot on board. They then say I should fit a resistor they
supply, it says it will drop maximum output to about 30mv p-p. I have
had some troubles getting a mike that will drive the bitx20a
properly... What maximum p-p I am best setting on my test oscillator
to drive into bitx20a mike socket?
Thanks, Dave Price - now MW0PRI (was 2W0DVP). p.s. kit from Walford
electronics in uk and generates a mix of about 1590hz and 725hz (or
one or other).

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Dear All,

I am still messing with final alignment of my bitx20a. Having read
advice, and given I quite like building things, I have just built a
simple "tone tone oscillator" kit to help set up the bitx20a. The kit
has an "optional" resistor to let me reduce output levels. Without it,
the maximum p-p voltage is about 450mv, but I can reduce that lots
with a pot on board. They then say I should fit a resistor they
supply, it says it will drop maximum output to about 30mv p-p. I have
had some troubles getting a mike that will drive the bitx20a
properly... What maximum p-p I am best setting on my test oscillator
to drive into bitx20a mike socket?
Thanks, Dave Price - now MW0PRI (was 2W0DVP). p.s. kit from Walford
electronics in uk and generates a mix of about 1590hz and 725hz (or
one or other).