Re: No RF Power Output From Bitx40
MOSFETs will blow from over-current faster than I can reach the controls, but
I am old and slow so your mileage may vary.?
Tune up has always been one of my complaints about the BITX design.? We
need a low-power output setting for adjusting the ATU, and then ability to switch
to higher power for normal use.? Back in the BITX20A and BITX17A days I used
an audio oscillator with two switch selected output levels.? Low level was used
to generate less than 0.1 watts output for tuning the ATU and high level AF out
for sending CW.? This works if the antenna is not too far from 50 ohms, but does
not protect the RF PA if no antenna is connected.?
Some have experimented with current-limited power supplies for the PA stage.
I'm not sure how effective that might have been.?
I wonder what might happen if a small resistance and bypass capacitor were
placed in series with the IRF510 source lead??
Back in the bad old days of vacuum tubes and thermionic emission we used
small inductances and parallel capacitors? in plate circuits to minimize parasitic
oscillations.??? The oscillation mode is different with MOSFETs? but this might
warrant? further exploration.
ALC circuits for the RF PA stage might be useful for detecting and taming some
oscillations, but might be tricky to adjust for SSB use.
I wonder if the RF PA voltage might be reduced to some low level for tune-up
and then switched to higher voltage for normal operation?? Using low voltage
on the drain lead during tune-up could cause non-linearity and spurious
outputs but for short-term tune-up action this might not be too objectionable.
Part of the attraction of BITX designs is that is always potential for modification
and hopefully improvement.
Arv? K7HKL
_._
On Sat, Jul 8, 2017 at 8:36 AM, Richard Andrew Knack via Groups.Io <ihc73scout2@...> wrote: How quickly will IRF-510's blow? And how much power will it take? In other words, if you have a transceiver or an amp that has them for finals, do you have time to use an automatic antenna tuner to get an impedance match? Or will the finals blow while the tuner is running through relays and inductances trying to find a match?
Rich KC8MWG
On Saturday, July 8, 2017, 10:31:21 AM EDT, Arv Evans < arvid.evans@...> wrote:
K3HJP
Like Raj said...the IRF510 is probably blown, usually due to transmitting into something other
than a 50 ohm load.? If the output impedance is too high the final will go into oscillation and
self-destruct.
Arv? K7HKL
_._
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Re: HELP NEEDED WITH ADDING USB FUNCTION TO EXISTING CODE.
Joe, there are two ways to get USB. The first way is what's offered in Allard's Raduino project which shifts CLK2 to 19MHz. The second way (which I'm going to be doing when life gets outta the way and lets me finish it) is to scrap the current BFO and use CLK0 for the BFO.
Vince.
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On 07/08/2017 12:21 PM, Joe wrote: Hi,
Myself and Adrian (VK4L) have been working on code developed by PD8W.
We believe it would be a very nice addition to software choices for our
fellow hams.
It works with an atmega 2560, a SI5351, a TFT colour display.
Just plug the display into the atmega and wire up the SI5351 along with
a few buttons.
Easy and that part works great.
After much effort I have been able to make the code work(almost),
It currently has a nice display layout and displays everything fine on
the TFT colour Display.
I tunes the Bitx40 very smoothly( rotary encoder).
I added a button to change the vfo freq time stepping it also works well.
Our goal is to *add USB,* so we can use it for *Digital modes.*
After burning many brains cells, (and at my age, I cannot afford to burn
to many) I cannot seem to get my head around making the code work for USB,
I tried cut and pastes from many codes and still no success.
We are both aware the existing code could be much better structured
From looking around the internet, I don't see any code offering the
functions with a good colour display.
I realize Jack , W8TEE is working on a great project and I have his
boards and parts populated and near ready.
However, this project is different. It offers off the shelf usage of
standard Arduino modules, and a plugin TFT Colour Display, and minimal
components..
Unfortunately, the author is not available for help to finish off a few
items.
It is is a pain to decode, but we are hoping someone can give us a hand
getting over this *1 major issue (adding USB function*).
Once this is done, the code will be completely functional and available
to anyone who would like it.
The additional items to display for tx / rx etc ... should not be a big
issue.
I have attached the code below
Any help would be much appreciated.
Joe
VE1BWV
--
Michigan VHF Corp.
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HELP NEEDED WITH ADDING USB FUNCTION TO EXISTING CODE.
Hi,
Myself and Adrian (VK4L) have been working on code developed by PD8W.
We believe it would be a very nice addition to software choices for our fellow hams.
It works with an atmega 2560, a SI5351, a TFT colour display.
Just plug the display into the atmega and wire up the SI5351 along with a few buttons.
Easy and that part works great.
After much effort I have been able to make the code work(almost),
It currently has a nice display layout and displays everything fine on the TFT colour Display.
I tunes the Bitx40 ?very smoothly( rotary encoder).
I added a button to change the vfo freq time stepping it ?also works well.
Our goal is to add USB, so we can use it for Digital modes.
After burning many brains cells, (and at my age, I cannot afford to burn to many) I cannot seem to get my head around making the code work for USB,
I tried cut and pastes from many codes and still no success.
We are both aware the existing code could be much better structured
From looking around the internet, I don't see any code offering the functions with a good colour display.
I realize Jack , W8TEE is working on a great project and I have his boards and parts populated and near ready.
However, this project is different. It offers off the shelf usage of standard Arduino modules, and a plugin TFT Colour Display, and ?minimal components..
Unfortunately, the author is not available for help to finish off a few items.
It is is a pain to decode, but we are hoping someone can give us a hand getting over this 1 major ?issue (adding USB function).
Once this is done, the code will be completely functional and available to anyone ?who would like it.
The ?additional items to display for tx / rx etc ... should not be a big issue.
I have attached the code below
Any help would be much appreciated.
Joe
VE1BWV
|
Whats the details of the C124 mod, and is there a diagram with the modded values for the AGC circuit.
On Tue, Jul 4, 2017 at 4:06 PM, chris gress <Chrisg0wfh@...> wrote: Nope but then I don't get a pop when I key up I have the c124 mod done I used? 6.8yf it was all I had?
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Re: Oops..I did it this time....
Oh...ok I see it.....nope still a blank screen, but the backlight is on...but the radio is not. Hi...guess somehow I fried the radiuno.
? I was varying the frequency of the bfo? crystal x5, and all the sudden the readout moved to 7.1000 mhz , and it wouldn't tune. So I cut it off, and cut it back on. Now the radio just hisses.
On Jul 8, 2017 10:37 AM, "David Woodward" < kf4wbj2@...> wrote:
Where is the pushbutton?
On Jul 8, 2017 8:04 AM, < greggaston@...> wrote: I did something similar.? If you hold the pushbutton in while powering up, it will reset the Radinuo to original "factory" settings.?
Greg
KD4VV
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Re: Oops..I did it this time....
Push button as in the Function switch.
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Re: No RF Power Output From Bitx40
I use my z-100 antenna tuner all the time to match up a dipole made with twin lead speaker wire...no problem so far (fingers crossed)...
On Jul 8, 2017 10:37 AM, "Richard Andrew Knack via Groups.Io" <ihc73scout2= [email protected]> wrote:
How quickly will IRF-510's blow? And how much power will it take? In other words, if you have a transceiver or an amp that has them for finals, do you have time to use an automatic antenna tuner to get an impedance match? Or will the finals blow while the tuner is running through relays and inductances trying to find a match?
Rich KC8MWG
On Saturday, July 8, 2017, 10:31:21 AM EDT, Arv Evans < arvid.evans@...> wrote:
K3HJP
Like Raj said...the IRF510 is probably blown, usually due to transmitting into something other
than a 50 ohm load.? If the output impedance is too high the final will go into oscillation and
self-destruct.
Arv? K7HKL
_._
|
Re: Oops..I did it this time....
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Show quoted text
I did something similar.? If you hold the pushbutton in while powering up, it will reset the Radinuo to original "factory" settings.?
Greg
KD4VV
|
Re: No RF Power Output From Bitx40
How quickly will IRF-510's blow? And how much power will it take? In other words, if you have a transceiver or an amp that has them for finals, do you have time to use an automatic antenna tuner to get an impedance match? Or will the finals blow while the tuner is running through relays and inductances trying to find a match?
Rich KC8MWG
On Saturday, July 8, 2017, 10:31:21 AM EDT, Arv Evans <arvid.evans@...> wrote:
K3HJP
Like Raj said...the IRF510 is probably blown, usually due to transmitting into something other
than a 50 ohm load.? If the output impedance is too high the final will go into oscillation and
self-destruct.
Arv? K7HKL
_._
|
Re: No RF Power Output From Bitx40
I do not see 5v on any terminal on U3
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Re: No RF Power Output From Bitx40
K3HJP
Like Raj said...the IRF510 is probably blown, usually due to transmitting into something other
than a 50 ohm load.? If the output impedance is too high the final will go into oscillation and
self-destruct.
Arv? K7HKL
_._
On Sat, Jul 8, 2017 at 7:32 AM, <Kc3hjp@...> wrote: Hi guys, I finally got around to finishing my Bitx40 project. Everything works but it will not transmit. This has me scratching my head. Here are some details.?
- when I press the PTT on the mic I can hear the relay pull in and receive audio goes away as it should.?
- I've verified that I have 12vdc on the PA connection and it's wired in the right direction.?
- mic element ohms out properly and it's wired in the right direction according to instructions
- 152mA on receive
- 260mA on transmit with no audio
- current may change by .001mA when yelling into the mic
- set PA bios pot makes no difference in current reading with mic keyed (audio/no audio)
- mic element 0.877k ohms in one direction and 1.101k ohms in other direction
- same mic ohm values on the mic connector and board connector
- 12vdc between the Gate and Drain of the PA. No voltage between the Gate and Source when mic is keyed
Any ideas?
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Re: No RF Power Output From Bitx40
Possibly. If your final is fine then the bias pot would work.
Check if U3 has 5V out.
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At 08/07/2017, you wrote: So this radio that has never transmitted before and has had a dummy load on it or an antenna every time the mic button has been pressed has a blown final?
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Re: No RF Power Output From Bitx40
So this radio that has never transmitted before and has had a dummy load on it or an antenna every time the mic button has been pressed has a blown final?
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Re: No RF Power Output From Bitx40
At 08/07/2017, you wrote: - set PA bios pot makes no difference in current reading with mic keyed (audio/no audio) Means final is blown. - mic element 0.877k ohms in one direction and 1.101k ohms in other direction I have not checked but I would expect a condensor mic to be open circuit when not connected to board. Unplug and check. - same mic ohm values on the mic connector and board connector
- 12vdc between the Gate and Drain of the PA. No voltage between the Gate and Source when mic is keyed
Any ideas?
|
Thanks Raj,
I¡¯ll try that tomorrow.
At the moment the antenna ground is connected to the case - and the power negative is also connected to the case.
I¡¯ll try isolating the antenna ground,
John
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On 8 Jul 2017, at 11:25 pm, Raj vu2zap <rajendrakumargg@...> wrote:
Thats good John,
Now unplug the antenna and just touch the antenna ground to rig rear connector ground.
Nothing should be heard on RX.
If you hear AM signals or noise - probably the socket to board may be an issue or a ground loop.
I have had a similar problem when my jumper cable from rig to SWR meter was frayed and ground
was open.
The antenna ground should be isolated from ground of other rear inputs/outputs. They are all connected
internally on the board.
Raj
At 08/07/2017, you wrote:
Hi Raj,
yes, I understood. From the board to the antenna connector is correct.
I???ve checked for continuity and for any shorts in the connection, but all seems ok.
I'll keep trying - and double checking the connections!
John
On 8 Jul 2017, at 11:11 pm, Raj vu2zap <rajendrakumargg@...> wrote:
Hi John,
Sorry I meant from the board to the antenna connector.
Check with a multimeter on beep continuity if the connections are proper to the connector.
At 08/07/2017, you wrote:
Hi Raj,
I??????ve double checked and just now checked again. Centre pin to antenna and shield to ground - all correct.
John
|
No RF Power Output From Bitx40
Hi guys, I finally got around to finishing my Bitx40 project. Everything works but it will not transmit. This has me scratching my head. Here are some details.? - when I press the PTT on the mic I can hear the relay pull in and receive audio goes away as it should.? - I've verified that I have 12vdc on the PA connection and it's wired in the right direction.? - mic element ohms out properly and it's wired in the right direction according to instructions
- 152mA on receive
- 260mA on transmit with no audio
- current may change by .001mA when yelling into the mic
- set PA bios pot makes no difference in current reading with mic keyed (audio/no audio)
- mic element 0.877k ohms in one direction and 1.101k ohms in other direction
- same mic ohm values on the mic connector and board connector
- 12vdc between the Gate and Drain of the PA. No voltage between the Gate and Source when mic is keyed
Any ideas?
|
Thats good John,
Now unplug the antenna and just touch the antenna ground to rig rear connector ground.
Nothing should be heard on RX.
If you hear AM signals or noise - probably the socket to board may be an issue or a ground loop.
I have had a similar problem when my jumper cable from rig to SWR meter was frayed and ground
was open.
The antenna ground should be isolated from ground of other rear inputs/outputs. They are all connected
internally on the board.
Raj
toggle quoted message
Show quoted text
At 08/07/2017, you wrote: Hi Raj,
yes, I understood. From the board to the antenna connector is correct.
I?€?ve checked for continuity and for any shorts in the connection, but all seems ok.
I'll keep trying - and double checking the connections!
John
On 8 Jul 2017, at 11:11 pm, Raj vu2zap <rajendrakumargg@...> wrote:
Hi John,
Sorry I meant from the board to the antenna connector.
Check with a multimeter on beep continuity if the connections are proper to the connector.
At 08/07/2017, you wrote:
Hi Raj,
I???€??ve double checked and just now checked again. Centre pin to antenna and shield to ground - all correct.
John
|
Hi Raj,
yes, I understood. From the board to the antenna connector is correct.
I¡¯ve checked for continuity and for any shorts in the connection, but all seems ok.
I'll keep trying - and double checking the connections!
John
toggle quoted message
Show quoted text
On 8 Jul 2017, at 11:11 pm, Raj vu2zap <rajendrakumargg@...> wrote:
Hi John,
Sorry I meant from the board to the antenna connector.
Check with a multimeter on beep continuity if the connections are proper to the connector.
At 08/07/2017, you wrote:
Hi Raj,
I???ve double checked and just now checked again. Centre pin to antenna and shield to ground - all correct.
John
|
Hi John,
Sorry I meant from the board to the antenna connector.
Check with a multimeter on beep continuity if the connections are proper to the connector.
toggle quoted message
Show quoted text
At 08/07/2017, you wrote: Hi Raj,
I?€?ve double checked and just now checked again. Centre pin to antenna and shield to ground - all correct.
John
|
Re: Oops..I did it this time....
I did something similar. ?If you hold the pushbutton in while powering up, it will reset the Radinuo to original "factory" settings.?
Greg
KD4VV
|
N8DAH
Raj vu2zap