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Re: Pop in speaker on key-up

 

Trip - KT4WO

The infamous BITX-Click has been well documented on this forum, but it was mostly
some time ago.?

There is a capacitor that couples the receive audio from the BFO mixer and another
capacitor that couples the microphone amplifier to the BFO mixer.? In Rx mode and in
Tx mode these capacitors get charged to different voltages.? When you change modes
these capacitors take on different voltages.? This causes a click when going from Tx
to Rx mode, and a 20 ms carrier burst when going from Rx to Tx mode.?

There have been several methods suggested to alleviate this situation, but basically
the situation is something that most will live with as a trade-off for simplicity and low
cost.? Once you have an antenna connected the receive-mode click should be less
noticeable.? 0.1 mfd across your speaker terminals might help minimize the click.?

Some of the early BITX20 and BITX17 builders resorted to using a relay to switch
microphone and speaker circuits as a way to eliminate this situation.? That too is
documented in the forum.

It is possible to make an LTSpice simulation that documents this situation, and that
might lead to simulator experimentation to come up with a solution to the problem.
In fact, any of the BITX circuit sub-sections can be ran in LTSpice as a means for
providing better understanding how they work and to trial proposed modifications
without having to melt solder.

Arv? K7HKL
_._


On Fri, Dec 16, 2016 at 4:05 PM, kt4wo67@... [BITX20] <BITX20@...> wrote:
?

Just to the controls hooked up...for testing. Upon key up I get a loud "pop" in the speaker.

I searched the group and didn't see this issue.?

Ideas??

Trip - KT4WO
kt4wo67@...
Re: Pop in speaker on key-up

Thomas Noel
 

开云体育

Trip et al,

It has been discussed before. Search for “PTT noise” or PTT transient”. Cause and solutions both simple (ignore it) and complex (Multi-transistor multi-relay switching schemes to cut the power during the crossover) have been described. Some of the discussion far predates the new SMT Bitx40 from India.

I have it with all cleaned up and in a fully shielded enclosure.

Thomas W Noel
KF7RSF

On Dec 16, 2016, at 3:27 PM, Joel Caulkins caulktel@... [BITX20] <BITX20@...> wrote:

?

Trip,

I found that while I had my board sprawled all over my bench that the click on Xmit was real loud with all my cables crossing each other, when I got the wiring cleaned up and separated and the power output cable replaced by a piece of RG-174 coax it's hardly noticeable anymore.

Joel Caulkins?KB6QVI

On Dec 16, 2016, at 3:05 PM, kt4wo67@... [BITX20] <BITX20@...> wrote:

?

Just to the controls hooked up...for testing. Upon key up I get a loud "pop" in the speaker.

I searched the group and didn't see this issue.?

Ideas??

Trip - KT4WO
kt4wo67@...
Re: Pop in speaker on key-up

 

开云体育

Trip,

I found that while I had my board sprawled all over my bench that the click on Xmit was real loud with all my cables crossing each other, when I got the wiring cleaned up and separated and the power output cable replaced by a piece of RG-174 coax it's hardly noticeable anymore.

Joel Caulkins?KB6QVI

On Dec 16, 2016, at 3:05 PM, kt4wo67@... [BITX20] <BITX20@...> wrote:

?

Just to the controls hooked up...for testing. Upon key up I get a loud "pop" in the speaker.

I searched the group and didn't see this issue.?

Ideas??

Trip - KT4WO
kt4wo67@...
Pop in speaker on key-up

[email protected]
 

Just to the controls hooked up...for testing. Upon key up I get a loud "pop" in the speaker.

I searched the group and didn't see this issue.?

Ideas??

Trip - KT4WO
kt4wo67@...
Re: Bitx 40 board.

 

There is an excellent and easy to remember rule of thumb on sideband inversion.? Explained here:




On Thursday, December 15, 2016 9:52 PM, "Ken Chase chase8043@... [BITX20]" wrote:


?
Hi John

I had a chance to try some testing with sideband inversion.

BFO = 11.9986 MHZ and VFO = 4.8486 MHZ this gives me a starting frequency of 7.15 MHZ(RF = BFO - VFO). Set the encoder to increase frequency in CW direction. But this to increase VFO or decreasing RF. So I switched it so RF goes up in CW direction.

I usually listen in on a net at 7.163 MHZ. To tune in the voice I had to increase RF. So I find that LSB is on the wrong side of the (non-existent) carrier.

Is this the sideband inversion?

73

Ken VA3ABN



On Thu, Dec 8, 2016 at 11:56 PM, iam74@... [BITX20] <BITX20@...> wrote:
?
Think of it this way: VFO - IF = RF. Does this result in sideband inversion? (hint: -IF + VFO. It it positive or negative?) Why don't you try it and see what happens. If you get nothing but garble, then the answer is "no...it does not.

If the results are clear signals, then you must decide if the LSB is being inverted, or is it truly USB. Remember that the ordinary condition by convention is that the LSB on 20m is garble or non-existent. Therefore you must hear USB inverted to LSB or true USB for intelligibility. Be aware of AM; test your results through several different QSOs.

Actually, it doesn't matter which it is -- as long as communication takes place.

john
AD5YE


---In BITX20@..., wrote :

Opps. Not?18.998600 - 4.998600 = 14.0. Should be 25.998600 - 11.988600 = 14 or is this the wrong sideband?

73 Ken
Re: Bitx 40 board.

 

Hi John

I had a chance to try some testing with sideband inversion.

BFO = 11.9986 MHZ and VFO = 4.8486 MHZ this gives me a starting frequency of 7.15 MHZ(RF = BFO - VFO). Set the encoder to increase frequency in CW direction. But this to increase VFO or decreasing RF. So I switched it so RF goes up in CW direction.

I usually listen in on a net at 7.163 MHZ. To tune in the voice I had to increase RF. So I find that LSB is on the wrong side of the (non-existent) carrier.

Is this the sideband inversion?

73

Ken VA3ABN



On Thu, Dec 8, 2016 at 11:56 PM, iam74@... [BITX20] <BITX20@...> wrote:
?

Think of it this way: VFO - IF = RF. Does this result in sideband inversion? (hint: -IF + VFO. It it positive or negative?) Why don't you try it and see what happens. If you get nothing but garble, then the answer is "no...it does not.

If the results are clear signals, then you must decide if the LSB is being inverted, or is it truly USB. Remember that the ordinary condition by convention is that the LSB on 20m is garble or non-existent. Therefore you must hear USB inverted to LSB or true USB for intelligibility. Be aware of AM; test your results through several different QSOs.

Actually, it doesn't matter which it is -- as long as communication takes place.

john
AD5YE



---In BITX20@..., wrote :

Opps. Not?18.998600 - 4.998600 = 14.0. Should be 25.998600 - 11.988600 = 14 or is this the wrong sideband?

73 Ken
Re: BitX40 Spectrum Output

 

Sure I'll do it now. Thanks.

Tom
Re: BitX40 Spectrum Output

 

tom,?

i couldn't find the other file. can you put them both under a folder with your callsign?

- f

On Thu, Dec 15, 2016 at 5:26 AM, thomasinaz@... [BITX20] <BITX20@...> wrote:
?

Hi everyone,


I'm going to upload 2 pics into the file section if someone is able to look at them for me. I have two signal approx 500-700k away from the tuned freg and less than 20dbm difference in output with the mic keyed and no audio.

Not sure if something is coupling to the antenna leads or what.


The signal to the far left is the vfo which is set from 4.7 to 4.9 MHz.


Thanks for any help in advance.


Tom

w7amh
New file uploaded to BITX20

[email protected]
 

Hello,


This email message is a notification to let you know that
a file has been uploaded to the Files area of the BITX20
group.


File : /BitX40 Spectrum Output/ssh.bmp
Uploaded by : tom_hurst@... <thomasinaz@...>
Description :


You can access this file at the URL:



To learn more about file sharing for your group, please visit:



Regards,


tom_hurst@... <thomasinaz@...>
New file uploaded to BITX20

[email protected]
 

Hello,


This email message is a notification to let you know that
a file has been uploaded to the Files area of the BITX20
group.


File : /BitX40 Spectrum Output/ssl.bmp
Uploaded by : tom_hurst@... <thomasinaz@...>
Description :


You can access this file at the URL:



To learn more about file sharing for your group, please visit:



Regards,


tom_hurst@... <thomasinaz@...>
BitX40 Spectrum Output

 

Hi everyone,


I'm going to upload 2 pics into the file section if someone is able to look at them for me. I have two signal approx 500-700k away from the tuned freg and less than 20dbm difference in output with the mic keyed and no audio.

Not sure if something is coupling to the antenna leads or what.


The signal to the far left is the vfo which is set from 4.7 to 4.9 MHz.


Thanks for any help in advance.


Tom

w7amh
Re: Bitx Drift

 

开云体育

?

On W5KUB (facebook) there is also the sketch. Not sure if attaching to this mail is the way to go.

?

Ron – PA3FAT

?

Van: BITX20@... [mailto:BITX20@...]
Verzonden: 14 December, 2016 03:37
Aan: BITX20@...
Onderwerp: Re: [BITX20] Re: Bitx Drift

?

?

Is there a schematic and write up on this VFO anywhere? It sure looks like a neat project. Thanks for posting it. ?

Ian ?K3HQL

?

?

On Tuesday, December 13, 2016 10:35 AM, "ron van doremalen ronvandoremalen@... [BITX20]" <BITX20@...> wrote:

?

?

Would this solve your problems:


Working with W5KUB, Tom Medlin, last days to get the Arduin/SI5351 to work.
Still needs some work but no more drift.

Ron – PA3FAT

?

Van: BITX20@... [mailto:BITX20@...]
Verzonden: 13 December, 2016 17:33
Aan: BITX20@...
Onderwerp: Re: [BITX20] Re: Bitx Drift

?

?

I have 100 NP0 caps for 1000pF and 150 pf. ?these are surface mount.? I would be happy to send some to anybody to try.? Just send a SASE to me (I am good on QRZ.com).? Note that I had a bit of difficulty with my mod, so your milage may vary. ?

73, Joe W3TTT

?

On Mon, Dec 12, 2016 at 8:38 PM, ohwenzelph@... [BITX20] <BITX20@...> wrote:

?

all true, but i store my toroids in air. when the radio is cookin', i'd bet that a toroid parked in the middle of the top ( i.e. the side with the warm resistors attached and the side where they would radiate from) of that board is warmer than one parked on the bottom side. sounds like a test worthy hypothesis... and, true or not, would that be a factor in VFO stability??

and while i have ordered npo caps, and have considered changing and moving the inductor, currently my indian made bitx and i are at opposite ends of a continent... so, sadly, i can only conjecture at this point. but it would be fun to actually measure and see if it makes any significant difference. i.e. does it really help to move the toroid to the bottom of the board?

?

?
Re: Digital Dial from QRPGuys

 

The noise from the frequency counters enters through the tap off point. The correct way is to build an isolation amplifier with a cascade pair of common base amplifiers between the VFO and the counter.?

- f

On Wed, Dec 14, 2016 at 9:01 AM, anglerhamming@... [BITX20] <BITX20@...> wrote:
?

I shield my DL4YHF homebrew LED counters. The one in the link is a homebrew SW-40+ receiver board and VFO. The VFO has feedthru caps for power and the 10-turn pot control wiring, and the signal to the receiver and the counter are shielded coax with RCA plugs. I've since replaced the copper PCB/copper tape counter enclosure with a brass box using hardware store stock as KC0WOX did on the Bitx. I've not had any noise problems with the counters.

DuWayne, I bought 3 of your "mini" DL4YHF boards a few months ago on Osh Park for future projects. I bought some .36" displays to use with them.

Ted, KX4OM



Re: Digital Dial from QRPGuys

 

I shield my DL4YHF homebrew LED counters. The one in the link is a homebrew SW-40+ receiver board and VFO. The VFO has feedthru caps for power and the 10-turn pot control wiring, and the signal to the receiver and the counter are shielded coax with RCA plugs. I've since replaced the copper PCB/copper tape counter enclosure with a brass box using hardware store stock as KC0WOX did on the Bitx. I've not had any noise problems with the counters.

DuWayne, I bought 3 of your "mini" DL4YHF boards a few months ago on Osh Park for future projects. I bought some .36" displays to use with them.

Ted, KX4OM


Re: Bitx Drift

 

Is there a schematic and write up on this VFO anywhere? It sure looks like a neat project. Thanks for posting it. ?
Ian ?K3HQL
?


On Tuesday, December 13, 2016 10:35 AM, "ron van doremalen ronvandoremalen@... [BITX20]" wrote:


?
Would this solve your problems:


Working with W5KUB, Tom Medlin, last days to get the Arduin/SI5351 to work.
Still needs some work but no more drift.

Ron – PA3FAT
?

Van: BITX20@... [mailto:BITX20@...]
Verzonden: 13 December, 2016 17:33
Aan: BITX20@...
Onderwerp: Re: [BITX20] Re: Bitx Drift
?
?
I have 100 NP0 caps for 1000pF and 150 pf. ?these are surface mount.? I would be happy to send some to anybody to try.? Just send a SASE to me (I am good on QRZ.com).? Note that I had a bit of difficulty with my mod, so your milage may vary. ?
73, Joe W3TTT
?
On Mon, Dec 12, 2016 at 8:38 PM, ohwenzelph@... [BITX20] <BITX20@...> wrote:
?
all true, but i store my toroids in air. when the radio is cookin', i'd bet that a toroid parked in the middle of the top ( i.e. the side with the warm resistors attached and the side where they would radiate from) of that board is warmer than one parked on the bottom side. sounds like a test worthy hypothesis... and, true or not, would that be a factor in VFO stability??
and while i have ordered npo caps, and have considered changing and moving the inductor, currently my indian made bitx and i are at opposite ends of a continent... so, sadly, i can only conjecture at this point. but it would be fun to actually measure and see if it makes any significant difference. i.e. does it really help to move the toroid to the bottom of the board?
?
Re: Bitx Drift

 

开云体育

Would this solve your problems:


Working with W5KUB, Tom Medlin, last days to get the Arduin/SI5351 to work.
Still needs some work but no more drift.

Ron – PA3FAT

?

Van: BITX20@... [mailto:BITX20@...]
Verzonden: 13 December, 2016 17:33
Aan: BITX20@...
Onderwerp: Re: [BITX20] Re: Bitx Drift

?

?

I have 100 NP0 caps for 1000pF and 150 pf. ?these are surface mount.? I would be happy to send some to anybody to try.? Just send a SASE to me (I am good on QRZ.com).? Note that I had a bit of difficulty with my mod, so your milage may vary. ?

73, Joe W3TTT

?

On Mon, Dec 12, 2016 at 8:38 PM, ohwenzelph@... [BITX20] <BITX20@...> wrote:

?

all true, but i store my toroids in air. when the radio is cookin', i'd bet that a toroid parked in the middle of the top ( i.e. the side with the warm resistors attached and the side where they would radiate from) of that board is warmer than one parked on the bottom side. sounds like a test worthy hypothesis... and, true or not, would that be a factor in VFO stability??

and while i have ordered npo caps, and have considered changing and moving the inductor, currently my indian made bitx and i are at opposite ends of a continent... so, sadly, i can only conjecture at this point. but it would be fun to actually measure and see if it makes any significant difference. i.e. does it really help to move the toroid to the bottom of the board?

?
Re: good news / Bad news

Baruch Atta
 

Raj
Yes, I was thinking of that.? But for me, it is better to put it away for a few days and both of us (me and the BitX) can cool off!

Joe

On Mon, Dec 12, 2016 at 11:55 PM, Raj vu2zap@... [BITX20] <BITX20@...> wrote:
?

Joe,

In the process of changing the caps you may have done some damage to neighboring parts.
Please check with a magnifying glass. A torroid lead may have broken off.

73 Raj vu2zap

At 12/12/2016, you wrote:
>
>
>I have some good news and some bad news regarding my work on the Bitx 40v3.
>
 >First, the good news.? I replaced the four caps that determine the frequency on the VFO, these are c91, c92, c94, c95 with NP0 grade caps.? The good news is that this made the VFO rock solid, no noticeable drift. Nice.?
>
>However, the bad news.? Now the frequency range is too low, even setting the c93 to the minimum.? But even worse, the sensitivity is now very low, not receiving any but the most loud signals. ?
>
>Now, I can probably fix the frequency range issue by removing turns from the coil.? But I am at a loss regarding the sensitivity issue.? Any clues?
>
>thanks
>Joe
Re: Bitx Drift

Baruch Atta
 

I have 100 NP0 caps for 1000pF and 150 pf. ?these are surface mount.? I would be happy to send some to anybody to try.? Just send a SASE to me (I am good on QRZ.com).? Note that I had a bit of difficulty with my mod, so your milage may vary. ?
73, Joe W3TTT

On Mon, Dec 12, 2016 at 8:38 PM, ohwenzelph@... [BITX20] <BITX20@...> wrote:
?

all true, but i store my toroids in air. when the radio is cookin', i'd bet that a toroid parked in the middle of the top ( i.e. the side with the warm resistors attached and the side where they would radiate from) of that board is warmer than one parked on the bottom side. sounds like a test worthy hypothesis... and, true or not, would that be a factor in VFO stability??

and while i have ordered npo caps, and have considered changing and moving the inductor, currently my indian made bitx and i are at opposite ends of a continent... so, sadly, i can only conjecture at this point. but it would be fun to actually measure and see if it makes any significant difference. i.e. does it really help to move the toroid to the bottom of the board?
Re: Digital Dial from QRPGuys

 

I used a home brew version of the DL4YHF counter, and also had noise.? To get rid of it, I installed a 100uF cap. across the power connector at the counter.? Put a 10mH RF choke in series with the positive voltage lead. and installed another 100uF capacitor to ground right at the power switch. Don't know if you could use other values of RF choke, the 10mH was what I had on hand.
DuWayne KV4QB
Re: Digital Dial from QRPGuys

 

Here's how I fixed a noise problem many years ago. This was a bitx20a but the noise cure ought to work for about any counter.

part 1

part2


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