Topics

uBitx v.4 build information

Rubens Kamimura
 

Evan, 

Obrigado pelas imagens.
Consegui queimar mais IRF510, hoje a tarde.
Inclusive os condutores +B (13,8Vcc e +B PA Power).

Evan,
Thanks for the images. I managed to burn more IRF510, this afternoon. Including + B conductors (13,8Vdc and + B PA Power).

 73 PY2PVB

Rubens Kamimura



Em qui., 16 de abr. de 2020 às 17:11, Evan Hand <elhandjr@...> escreveu:

As promised in my prior replay, here is the link to the oscilloscope screen pictures that I took:
https://groups.io/g/BITX20/message/72786

Note that these are for test point 3 to 7 (in reverse order on the email).

Hope this helps.
73
Evan
AC9TU

Evan Hand
 

As promised in my prior replay, here is the link to the oscilloscope screen pictures that I took:
https://groups.io/g/BITX20/message/72786

Note that these are for test point 3 to 7 (in reverse order on the email).

Hope this helps.
73
Evan
AC9TU

Rubens Kamimura
 

Hi Evan

It was feeding the PA with 20Vdc, through a boost (step up converting 13.8Vdc to 20Vdc), therefore with a different power supply.
I noticed that I am not receiving any signal on JTDX (FT8) at the moment. I'll check if signs will arrive later to be sure. With reference to the oscilloscope (type) I have two of two channels if I'm not mistaken, I need to remove the cobwebs ... check if I still have their software on the laptop ... then I will check the signals on the gates, emitter of Q90, etc.
73

Rubens PY2PVB
--
Saudações fraternais, 73/51 PY2PVB

Rubens Kamimura
Tel. (18) 3746-8680 ramal 116
Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255 


Em qui., 16 de abr. de 2020 às 14:28, Evan Hand <elhandjr@...> escreveu:

Rubens,
Suggestion, verify that the receive function works, then try the transmit function without the power to the PA connection.  You should be able to verify the bias settings as being adjustable from 0 volts to 4 volts or so.  The bias is only applied when the PTT or CW ket is pressed.

I would also check to see if I am getting a drive signal at the gate of the finals.  I did this on my uBITX using an oscilloscope.  I cannot find the pictures I took, and need to run out and get food.  Will check again later.

73
Evan
AC9TU

Evan Hand
 

Rubens,
Suggestion, verify that the receive function works, then try the transmit function without the power to the PA connection.  You should be able to verify the bias settings as being adjustable from 0 volts to 4 volts or so.  The bias is only applied when the PTT or CW ket is pressed.

I would also check to see if I am getting a drive signal at the gate of the finals.  I did this on my uBITX using an oscilloscope.  I cannot find the pictures I took, and need to run out and get food.  Will check again later.

73
Evan
AC9TU

Rubens Kamimura
 

Hi Bill,

What value of C81, would you recommend to have better performance in the frequency of 7,074MHz (40 in FT8). In the diagrams we find several recommendations for values for C81: 470pF, 100nF, 10nF ... (0.01uF).

73

Rubens PY2PVB
--
Saudações fraternais, 73/51 PY2PVB

Rubens Kamimura
Tel. (18) 3746-8680 ramal 116
Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255 


Em qui., 16 de abr. de 2020 às 13:56, Bill Cromwell <wrcromwell@...> escreveu:

Hi Rubens,

Not to offend but things you mentioned as obvious are not obvious and
not stated in your post. That RV1 controls the drive level though Q90 in
my V3 (if I recall correctly) and in turn controls the finals. That
transistor sets the drive level. Mine is currently dead. Yours may have
been damaged when the finals and your meter were burned out. You did not
mention looking there. That is the next place I would look. I have only
just cleared my workbench of other people's radios and I will now
replace that transistor in my own radio:)

73,

Bill  KU8H

On 4/16/20 11:29 AM, Rubens Kamimura wrote:
> Bill
>
> Thanks for answering me!
> Obviously, I fulfilled the ritual to the letter, as I have been in the
> maintenance area for over 45 years.
> With reference to the voltage gradient of the converter booster (stepup)
> convert, at empty we have 20Vcc adjusted in the multiturn trimmer and in
> TX, obviously the voltage drops (dropped to 19.98Vcc). So I found it
> strange 20.00 - 19.98 = 0.02Vdc, and as V = R x I, considering R = 0.34
> ohms and V = 20Vdc, we would have a current of approximately 588.24mA,
> ignoring losses. We have something strange ... 588mA - 200mA = 388mA
> (current in TX, discounted Ibias).
>
> 73 PY2PVB
>
> Rubens Kamimura
> Cel.+55 (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>
>
> Em qui., 16 de abr. de 2020 às 12:11, Bill Cromwell
> <wrcromwell@... <mailto:wrcromwell@...>> escreveu:
>
>     Hi,
>
>     Did you reset the bias pots for the finals at the new voltage? You
>     would
>     have to set them to minimum (full clockwise) and then apply power. Go
>     through the whole procedure for setting the bias with the 20 volts
>     applied instead of the previous 12 volts.
>
>     Can your buck/boost gizmo supply enough current. Twenty volts with no
>     load drops to what voltage when transmitting (measured at the radio)?
>
>     73,
>
>     Bill  KU8H
>
>
>
>     On 4/16/20 10:40 AM, Rubens Kamimura wrote:
>      > All
>      >
>      > Step Up (boost converter) arrived, so I get 20Vdc output from
>     13.8Vdc
>      > input, I used 20Vdc to power PA Power of uBITX v4, when adjusting
>     the
>      > Ibias, the current went up at once reaching 15A , obviously damaged
>      > IRF510, PA Power plug, Ammeter ... I replaced the damaged
>     components, so
>      > this time I installed a 0.34 Ohms power resistor (5W) in series
>     with the
>      > step up output (20Vdc), but the output power is low, even with
>     RV1 at
>      > maximum ... and C81 capacitor with 100nF, I only got about 8W.
>      >
>      > What can I do now?
>      >
>      > 73 PY2PVB
>      >
>      > Rubens Kamimura .'.
>      > Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>      >
>      >
>      > Em ter., 7 de abr. de 2020 às 15:44, Rubens Kamimura via
>     groups.io <http://groups.io>
>      > <http://groups.io> <rubens.kamimura=gmail.com@groups.io
>     <mailto:gmail.com@groups.io>
>      > <mailto:gmail.com@groups.io <mailto:gmail.com@groups.io>>> escreveu:
>      >
>      >     Evan,
>      >
>      >     Ok, tks.
>      >
>      >     73 de Rubens py2pvb
>      >     --
>      >     Saudações fraternais, 73/51 PY2PVB
>      >
>      >     Rubens Kamimura
>      >     Tel. (18) 3746-8680 ramal 116
>      >     Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>      >
>      >
>      >     Em ter., 7 de abr. de 2020 às 14:16, Evan Hand
>     <elhandjr@... <mailto:elhandjr@...>
>      >     <mailto:elhandjr@... <mailto:elhandjr@...>>>
>     escreveu:
>      >
>      >         Rubens,
>      >
>      >         Most likely it was heat that fried your finals.  Digital
>     modes
>      >         have been reported to have this issue on all of the uBiTx
>      >         models, as they keep the transmitter on for 15 seconds at
>     a time
>      >         at full power.  Before going back on the air I would suggest
>      >         that you add a fan, larger heatsinks, or both.  Remember that
>      >         the stock radio does not have electrical isolation of the
>      >         heatsinks.  Either keep the new heatsinks isolated, or
>     add the
>      >         insulators for the IRF510s.  The alternative is to reduce the
>      >         output power with the RV1 adjustment.  I would adjust RV1
>     using
>      >         an RF power meter and keep it under 10 watts for 40 meters.
>      >         Monitor your finals temperature to verify that they are not
>      >         getting too hot.  As long as you can keep your finger on them
>      >         right after the end of transmission, then they should be
>     OK.  I
>      >         would send a continuous tune signal for at least 15
>     seconds into
>      >         a dummy load, turn off the power and immediately check the
>      >         finals.  I did learn that if you do not turn off the power,
>      >         there is a large risk that you will move the heatsink and
>     short
>      >         it out, usually just blowing the fuse.
>      >
>      >         As to how to set up the bias values for the new finals, there
>      >         are instructions on the HF Signals and ubitx.net
>     <http://ubitx.net>
>      >         <http://ubitx.net> sights.  I have used HF Signals for
>     the bias
>      >         adjustment:
>      > https://www.hfsignals.com/index.php/ubitx-tuneup/
>      >
>      >         You should not need to adjust the BFO or frequency
>     calibration.
>      >
>      >         The above are just suggestions.  There may be better ways
>     to do
>      >         the testing, however, the ones that I know of would
>     require an
>      >         IR measurement device.
>      >         73
>      >         Evan
>      >         AC9TU
>      >
>      >
>
>     --
>     bark less - wag more
>
>
>
>

--
bark less - wag more



Rubens Kamimura
 

Hi Bill,

No recent reviews! Thank you for remembering the Q90, I will check if it broke or changed, it is better to change it.
I will take the opportunity to check from C80 onwards. Grateful for the tips.

73 by Rubens PY2PVB
Cel. +55 (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255 


Em qui., 16 de abr. de 2020 às 13:56, Bill Cromwell <wrcromwell@...> escreveu:

Hi Rubens,

Not to offend but things you mentioned as obvious are not obvious and
not stated in your post. That RV1 controls the drive level though Q90 in
my V3 (if I recall correctly) and in turn controls the finals. That
transistor sets the drive level. Mine is currently dead. Yours may have
been damaged when the finals and your meter were burned out. You did not
mention looking there. That is the next place I would look. I have only
just cleared my workbench of other people's radios and I will now
replace that transistor in my own radio:)

73,

Bill  KU8H

On 4/16/20 11:29 AM, Rubens Kamimura wrote:
> Bill
>
> Thanks for answering me!
> Obviously, I fulfilled the ritual to the letter, as I have been in the
> maintenance area for over 45 years.
> With reference to the voltage gradient of the converter booster (stepup)
> convert, at empty we have 20Vcc adjusted in the multiturn trimmer and in
> TX, obviously the voltage drops (dropped to 19.98Vcc). So I found it
> strange 20.00 - 19.98 = 0.02Vdc, and as V = R x I, considering R = 0.34
> ohms and V = 20Vdc, we would have a current of approximately 588.24mA,
> ignoring losses. We have something strange ... 588mA - 200mA = 388mA
> (current in TX, discounted Ibias).
>
> 73 PY2PVB
>
> Rubens Kamimura
> Cel.+55 (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>
>
> Em qui., 16 de abr. de 2020 às 12:11, Bill Cromwell
> <wrcromwell@... <mailto:wrcromwell@...>> escreveu:
>
>     Hi,
>
>     Did you reset the bias pots for the finals at the new voltage? You
>     would
>     have to set them to minimum (full clockwise) and then apply power. Go
>     through the whole procedure for setting the bias with the 20 volts
>     applied instead of the previous 12 volts.
>
>     Can your buck/boost gizmo supply enough current. Twenty volts with no
>     load drops to what voltage when transmitting (measured at the radio)?
>
>     73,
>
>     Bill  KU8H
>
>
>
>     On 4/16/20 10:40 AM, Rubens Kamimura wrote:
>      > All
>      >
>      > Step Up (boost converter) arrived, so I get 20Vdc output from
>     13.8Vdc
>      > input, I used 20Vdc to power PA Power of uBITX v4, when adjusting
>     the
>      > Ibias, the current went up at once reaching 15A , obviously damaged
>      > IRF510, PA Power plug, Ammeter ... I replaced the damaged
>     components, so
>      > this time I installed a 0.34 Ohms power resistor (5W) in series
>     with the
>      > step up output (20Vdc), but the output power is low, even with
>     RV1 at
>      > maximum ... and C81 capacitor with 100nF, I only got about 8W.
>      >
>      > What can I do now?
>      >
>      > 73 PY2PVB
>      >
>      > Rubens Kamimura .'.
>      > Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>      >
>      >
>      > Em ter., 7 de abr. de 2020 às 15:44, Rubens Kamimura via
>     groups.io <http://groups.io>
>      > <http://groups.io> <rubens.kamimura=gmail.com@groups.io
>     <mailto:gmail.com@groups.io>
>      > <mailto:gmail.com@groups.io <mailto:gmail.com@groups.io>>> escreveu:
>      >
>      >     Evan,
>      >
>      >     Ok, tks.
>      >
>      >     73 de Rubens py2pvb
>      >     --
>      >     Saudações fraternais, 73/51 PY2PVB
>      >
>      >     Rubens Kamimura
>      >     Tel. (18) 3746-8680 ramal 116
>      >     Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>      >
>      >
>      >     Em ter., 7 de abr. de 2020 às 14:16, Evan Hand
>     <elhandjr@... <mailto:elhandjr@...>
>      >     <mailto:elhandjr@... <mailto:elhandjr@...>>>
>     escreveu:
>      >
>      >         Rubens,
>      >
>      >         Most likely it was heat that fried your finals.  Digital
>     modes
>      >         have been reported to have this issue on all of the uBiTx
>      >         models, as they keep the transmitter on for 15 seconds at
>     a time
>      >         at full power.  Before going back on the air I would suggest
>      >         that you add a fan, larger heatsinks, or both.  Remember that
>      >         the stock radio does not have electrical isolation of the
>      >         heatsinks.  Either keep the new heatsinks isolated, or
>     add the
>      >         insulators for the IRF510s.  The alternative is to reduce the
>      >         output power with the RV1 adjustment.  I would adjust RV1
>     using
>      >         an RF power meter and keep it under 10 watts for 40 meters.
>      >         Monitor your finals temperature to verify that they are not
>      >         getting too hot.  As long as you can keep your finger on them
>      >         right after the end of transmission, then they should be
>     OK.  I
>      >         would send a continuous tune signal for at least 15
>     seconds into
>      >         a dummy load, turn off the power and immediately check the
>      >         finals.  I did learn that if you do not turn off the power,
>      >         there is a large risk that you will move the heatsink and
>     short
>      >         it out, usually just blowing the fuse.
>      >
>      >         As to how to set up the bias values for the new finals, there
>      >         are instructions on the HF Signals and ubitx.net
>     <http://ubitx.net>
>      >         <http://ubitx.net> sights.  I have used HF Signals for
>     the bias
>      >         adjustment:
>      > https://www.hfsignals.com/index.php/ubitx-tuneup/
>      >
>      >         You should not need to adjust the BFO or frequency
>     calibration.
>      >
>      >         The above are just suggestions.  There may be better ways
>     to do
>      >         the testing, however, the ones that I know of would
>     require an
>      >         IR measurement device.
>      >         73
>      >         Evan
>      >         AC9TU
>      >
>      >
>
>     --
>     bark less - wag more
>
>
>
>

--
bark less - wag more



Bill Cromwell
 

Hi Rubens,

Not to offend but things you mentioned as obvious are not obvious and not stated in your post. That RV1 controls the drive level though Q90 in my V3 (if I recall correctly) and in turn controls the finals. That transistor sets the drive level. Mine is currently dead. Yours may have been damaged when the finals and your meter were burned out. You did not mention looking there. That is the next place I would look. I have only just cleared my workbench of other people's radios and I will now replace that transistor in my own radio:)

73,

Bill KU8H

On 4/16/20 11:29 AM, Rubens Kamimura wrote:
Bill
Thanks for answering me!
Obviously, I fulfilled the ritual to the letter, as I have been in the maintenance area for over 45 years.
With reference to the voltage gradient of the converter booster (stepup) convert, at empty we have 20Vcc adjusted in the multiturn trimmer and in TX, obviously the voltage drops (dropped to 19.98Vcc). So I found it strange 20.00 - 19.98 = 0.02Vdc, and as V = R x I, considering R = 0.34 ohms and V = 20Vdc, we would have a current of approximately 588.24mA, ignoring losses. We have something strange ... 588mA - 200mA = 388mA (current in TX, discounted Ibias).
73 PY2PVB
Rubens Kamimura
Cel.+55 (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
Em qui., 16 de abr. de 2020 às 12:11, Bill Cromwell <wrcromwell@... <mailto:wrcromwell@...>> escreveu:
Hi,
Did you reset the bias pots for the finals at the new voltage? You
would
have to set them to minimum (full clockwise) and then apply power. Go
through the whole procedure for setting the bias with the 20 volts
applied instead of the previous 12 volts.
Can your buck/boost gizmo supply enough current. Twenty volts with no
load drops to what voltage when transmitting (measured at the radio)?
73,
Bill  KU8H
On 4/16/20 10:40 AM, Rubens Kamimura wrote:
> All
>
> Step Up (boost converter) arrived, so I get 20Vdc output from
13.8Vdc
> input, I used 20Vdc to power PA Power of uBITX v4, when adjusting
the
> Ibias, the current went up at once reaching 15A , obviously damaged
> IRF510, PA Power plug, Ammeter ... I replaced the damaged
components, so
> this time I installed a 0.34 Ohms power resistor (5W) in series
with the
> step up output (20Vdc), but the output power is low, even with
RV1 at
> maximum ... and C81 capacitor with 100nF, I only got about 8W.
>
> What can I do now?
>
> 73 PY2PVB
>
> Rubens Kamimura .'.
> Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>
>
> Em ter., 7 de abr. de 2020 às 15:44, Rubens Kamimura via
groups.io <http://groups.io>
> <http://groups.io> <rubens.kamimura=gmail.com@groups.io
<mailto:gmail.com@groups.io>
> <mailto:gmail.com@groups.io <mailto:gmail.com@groups.io>>> escreveu:
>
>     Evan,
>
>     Ok, tks.
>
>     73 de Rubens py2pvb
>     --
>     Saudações fraternais, 73/51 PY2PVB
>
>     Rubens Kamimura
>     Tel. (18) 3746-8680 ramal 116
>     Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>
>
>     Em ter., 7 de abr. de 2020 às 14:16, Evan Hand
<elhandjr@... <mailto:elhandjr@...>
>     <mailto:elhandjr@... <mailto:elhandjr@...>>>
escreveu:
>
>         Rubens,
>
>         Most likely it was heat that fried your finals.  Digital
modes
>         have been reported to have this issue on all of the uBiTx
>         models, as they keep the transmitter on for 15 seconds at
a time
>         at full power.  Before going back on the air I would suggest
>         that you add a fan, larger heatsinks, or both.  Remember that
>         the stock radio does not have electrical isolation of the
>         heatsinks.  Either keep the new heatsinks isolated, or
add the
>         insulators for the IRF510s.  The alternative is to reduce the
>         output power with the RV1 adjustment.  I would adjust RV1
using
>         an RF power meter and keep it under 10 watts for 40 meters.
>         Monitor your finals temperature to verify that they are not
>         getting too hot.  As long as you can keep your finger on them
>         right after the end of transmission, then they should be
OK.  I
>         would send a continuous tune signal for at least 15
seconds into
>         a dummy load, turn off the power and immediately check the
>         finals.  I did learn that if you do not turn off the power,
>         there is a large risk that you will move the heatsink and
short
>         it out, usually just blowing the fuse.
>
>         As to how to set up the bias values for the new finals, there
>         are instructions on the HF Signals and ubitx.net
<http://ubitx.net>
>         <http://ubitx.net> sights.  I have used HF Signals for
the bias
>         adjustment:
> https://www.hfsignals.com/index.php/ubitx-tuneup/
>
>         You should not need to adjust the BFO or frequency
calibration.
>
>         The above are just suggestions.  There may be better ways
to do
>         the testing, however, the ones that I know of would
require an
>         IR measurement device.
>         73
>         Evan
>         AC9TU
>
>
--
bark less - wag more
--
bark less - wag more

Rubens Kamimura
 

Bill

Thanks for answering me!
Obviously, I fulfilled the ritual to the letter, as I have been in the maintenance area for over 45 years.
With reference to the voltage gradient of the converter booster (stepup) convert, at empty we have 20Vcc adjusted in the multiturn trimmer and in TX, obviously the voltage drops (dropped to 19.98Vcc). So I found it strange 20.00 - 19.98 = 0.02Vdc, and as V = R x I, considering R = 0.34 ohms and V = 20Vdc, we would have a current of approximately 588.24mA, ignoring losses. We have something strange ... 588mA - 200mA = 388mA (current in TX, discounted Ibias).

73 PY2PVB

Rubens Kamimura
Cel.+55 (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255 


Em qui., 16 de abr. de 2020 às 12:11, Bill Cromwell <wrcromwell@...> escreveu:

Hi,

Did you reset the bias pots for the finals at the new voltage? You would
have to set them to minimum (full clockwise) and then apply power. Go
through the whole procedure for setting the bias with the 20 volts
applied instead of the previous 12 volts.

Can your buck/boost gizmo supply enough current. Twenty volts with no
load drops to what voltage when transmitting (measured at the radio)?

73,

Bill  KU8H



On 4/16/20 10:40 AM, Rubens Kamimura wrote:
> All
>
> Step Up (boost converter) arrived, so I get 20Vdc output from 13.8Vdc
> input, I used 20Vdc to power PA Power of uBITX v4, when adjusting the
> Ibias, the current went up at once reaching 15A , obviously damaged
> IRF510, PA Power plug, Ammeter ... I replaced the damaged components, so
> this time I installed a 0.34 Ohms power resistor (5W) in series with the
> step up output (20Vdc), but the output power is low, even with RV1 at
> maximum ... and C81 capacitor with 100nF, I only got about 8W.
>
> What can I do now?
>
> 73 PY2PVB
>
> Rubens Kamimura .'.
> Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>
>
> Em ter., 7 de abr. de 2020 às 15:44, Rubens Kamimura via groups.io
> <http://groups.io> <rubens.kamimura=gmail.com@groups.io
> <mailto:gmail.com@groups.io>> escreveu:
>
>     Evan,
>
>     Ok, tks.
>
>     73 de Rubens py2pvb
>     --
>     Saudações fraternais, 73/51 PY2PVB
>
>     Rubens Kamimura
>     Tel. (18) 3746-8680 ramal 116
>     Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
>
>
>     Em ter., 7 de abr. de 2020 às 14:16, Evan Hand <elhandjr@...
>     <mailto:elhandjr@...>> escreveu:
>
>         Rubens,
>
>         Most likely it was heat that fried your finals.  Digital modes
>         have been reported to have this issue on all of the uBiTx
>         models, as they keep the transmitter on for 15 seconds at a time
>         at full power.  Before going back on the air I would suggest
>         that you add a fan, larger heatsinks, or both.  Remember that
>         the stock radio does not have electrical isolation of the
>         heatsinks.  Either keep the new heatsinks isolated, or add the
>         insulators for the IRF510s.  The alternative is to reduce the
>         output power with the RV1 adjustment.  I would adjust RV1 using
>         an RF power meter and keep it under 10 watts for 40 meters.
>         Monitor your finals temperature to verify that they are not
>         getting too hot.  As long as you can keep your finger on them
>         right after the end of transmission, then they should be OK.  I
>         would send a continuous tune signal for at least 15 seconds into
>         a dummy load, turn off the power and immediately check the
>         finals.  I did learn that if you do not turn off the power,
>         there is a large risk that you will move the heatsink and short
>         it out, usually just blowing the fuse.
>
>         As to how to set up the bias values for the new finals, there
>         are instructions on the HF Signals and ubitx.net
>         <http://ubitx.net> sights.  I have used HF Signals for the bias
>         adjustment:
>         https://www.hfsignals.com/index.php/ubitx-tuneup/
>
>         You should not need to adjust the BFO or frequency calibration.
>
>         The above are just suggestions.  There may be better ways to do
>         the testing, however, the ones that I know of would require an
>         IR measurement device.
>         73
>         Evan
>         AC9TU
>
>

--
bark less - wag more



Bill Cromwell
 

Hi,

Did you reset the bias pots for the finals at the new voltage? You would have to set them to minimum (full clockwise) and then apply power. Go through the whole procedure for setting the bias with the 20 volts applied instead of the previous 12 volts.

Can your buck/boost gizmo supply enough current. Twenty volts with no load drops to what voltage when transmitting (measured at the radio)?

73,

Bill KU8H

On 4/16/20 10:40 AM, Rubens Kamimura wrote:
All
Step Up (boost converter) arrived, so I get 20Vdc output from 13.8Vdc input, I used 20Vdc to power PA Power of uBITX v4, when adjusting the Ibias, the current went up at once reaching 15A , obviously damaged IRF510, PA Power plug, Ammeter ... I replaced the damaged components, so this time I installed a 0.34 Ohms power resistor (5W) in series with the step up output (20Vdc), but the output power is low, even with RV1 at maximum ... and C81 capacitor with 100nF, I only got about 8W.
What can I do now?
73 PY2PVB
Rubens Kamimura .'.
Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
Em ter., 7 de abr. de 2020 às 15:44, Rubens Kamimura via groups.io <http://groups.io> <rubens.kamimura=gmail.com@groups.io <mailto:gmail.com@groups.io>> escreveu:
Evan,
Ok, tks.
73 de Rubens py2pvb
--
Saudações fraternais, 73/51 PY2PVB
Rubens Kamimura
Tel. (18) 3746-8680 ramal 116
Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255
Em ter., 7 de abr. de 2020 às 14:16, Evan Hand <elhandjr@...
<mailto:elhandjr@...>> escreveu:
Rubens,
Most likely it was heat that fried your finals.  Digital modes
have been reported to have this issue on all of the uBiTx
models, as they keep the transmitter on for 15 seconds at a time
at full power.  Before going back on the air I would suggest
that you add a fan, larger heatsinks, or both.  Remember that
the stock radio does not have electrical isolation of the
heatsinks.  Either keep the new heatsinks isolated, or add the
insulators for the IRF510s.  The alternative is to reduce the
output power with the RV1 adjustment.  I would adjust RV1 using
an RF power meter and keep it under 10 watts for 40 meters. Monitor your finals temperature to verify that they are not
getting too hot.  As long as you can keep your finger on them
right after the end of transmission, then they should be OK.  I
would send a continuous tune signal for at least 15 seconds into
a dummy load, turn off the power and immediately check the
finals.  I did learn that if you do not turn off the power,
there is a large risk that you will move the heatsink and short
it out, usually just blowing the fuse.
As to how to set up the bias values for the new finals, there
are instructions on the HF Signals and ubitx.net
<http://ubitx.net> sights.  I have used HF Signals for the bias
adjustment:
https://www.hfsignals.com/index.php/ubitx-tuneup/
You should not need to adjust the BFO or frequency calibration.
The above are just suggestions.  There may be better ways to do
the testing, however, the ones that I know of would require an
IR measurement device.
73
Evan
AC9TU
--
bark less - wag more

Rubens Kamimura
 

All

Step Up (boost converter) arrived, so I get 20Vdc output from 13.8Vdc input, I used 20Vdc to power PA Power of uBITX v4, when adjusting the Ibias, the current went up at once reaching 15A , obviously damaged IRF510, PA Power plug, Ammeter ... I replaced the damaged components, so this time I installed a 0.34 Ohms power resistor (5W) in series with the step up output (20Vdc), but the output power is low, even with RV1 at maximum ... and C81 capacitor with 100nF, I only got about 8W.

What can I do now?

73 PY2PVB

Rubens Kamimura .'.
Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255 


Em ter., 7 de abr. de 2020 às 15:44, Rubens Kamimura via groups.io <rubens.kamimura=gmail.com@groups.io> escreveu:

Evan,

Ok, tks.

73 de Rubens py2pvb 
--
Saudações fraternais, 73/51 PY2PVB

Rubens Kamimura
Tel. (18) 3746-8680 ramal 116
Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255 


Em ter., 7 de abr. de 2020 às 14:16, Evan Hand <elhandjr@...> escreveu:
Rubens,

Most likely it was heat that fried your finals.  Digital modes have been reported to have this issue on all of the uBiTx models, as they keep the transmitter on for 15 seconds at a time at full power.  Before going back on the air I would suggest that you add a fan, larger heatsinks, or both.  Remember that the stock radio does not have electrical isolation of the heatsinks.  Either keep the new heatsinks isolated, or add the insulators for the IRF510s.  The alternative is to reduce the output power with the RV1 adjustment.  I would adjust RV1 using an RF power meter and keep it under 10 watts for 40 meters.  Monitor your finals temperature to verify that they are not getting too hot.  As long as you can keep your finger on them right after the end of transmission, then they should be OK.  I would send a continuous tune signal for at least 15 seconds into a dummy load, turn off the power and immediately check the finals.  I did learn that if you do not turn off the power, there is a large risk that you will move the heatsink and short it out, usually just blowing the fuse.

As to how to set up the bias values for the new finals, there are instructions on the HF Signals and ubitx.net sights.  I have used HF Signals for the bias adjustment:
https://www.hfsignals.com/index.php/ubitx-tuneup/

You should not need to adjust the BFO or frequency calibration.

The above are just suggestions.  There may be better ways to do the testing, however, the ones that I know of would require an IR measurement device.
73
Evan
AC9TU

Rubens Kamimura
 

Evan,

Ok, tks.

73 de Rubens py2pvb 
--
Saudações fraternais, 73/51 PY2PVB

Rubens Kamimura
Tel. (18) 3746-8680 ramal 116
Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255 


Em ter., 7 de abr. de 2020 às 14:16, Evan Hand <elhandjr@...> escreveu:

Rubens,

Most likely it was heat that fried your finals.  Digital modes have been reported to have this issue on all of the uBiTx models, as they keep the transmitter on for 15 seconds at a time at full power.  Before going back on the air I would suggest that you add a fan, larger heatsinks, or both.  Remember that the stock radio does not have electrical isolation of the heatsinks.  Either keep the new heatsinks isolated, or add the insulators for the IRF510s.  The alternative is to reduce the output power with the RV1 adjustment.  I would adjust RV1 using an RF power meter and keep it under 10 watts for 40 meters.  Monitor your finals temperature to verify that they are not getting too hot.  As long as you can keep your finger on them right after the end of transmission, then they should be OK.  I would send a continuous tune signal for at least 15 seconds into a dummy load, turn off the power and immediately check the finals.  I did learn that if you do not turn off the power, there is a large risk that you will move the heatsink and short it out, usually just blowing the fuse.

As to how to set up the bias values for the new finals, there are instructions on the HF Signals and ubitx.net sights.  I have used HF Signals for the bias adjustment:
https://www.hfsignals.com/index.php/ubitx-tuneup/

You should not need to adjust the BFO or frequency calibration.

The above are just suggestions.  There may be better ways to do the testing, however, the ones that I know of would require an IR measurement device.
73
Evan
AC9TU

Evan Hand
 

Rubens,

Most likely it was heat that fried your finals.  Digital modes have been reported to have this issue on all of the uBiTx models, as they keep the transmitter on for 15 seconds at a time at full power.  Before going back on the air I would suggest that you add a fan, larger heatsinks, or both.  Remember that the stock radio does not have electrical isolation of the heatsinks.  Either keep the new heatsinks isolated, or add the insulators for the IRF510s.  The alternative is to reduce the output power with the RV1 adjustment.  I would adjust RV1 using an RF power meter and keep it under 10 watts for 40 meters.  Monitor your finals temperature to verify that they are not getting too hot.  As long as you can keep your finger on them right after the end of transmission, then they should be OK.  I would send a continuous tune signal for at least 15 seconds into a dummy load, turn off the power and immediately check the finals.  I did learn that if you do not turn off the power, there is a large risk that you will move the heatsink and short it out, usually just blowing the fuse.

As to how to set up the bias values for the new finals, there are instructions on the HF Signals and ubitx.net sights.  I have used HF Signals for the bias adjustment:
https://www.hfsignals.com/index.php/ubitx-tuneup/

You should not need to adjust the BFO or frequency calibration.

The above are just suggestions.  There may be better ways to do the testing, however, the ones that I know of would require an IR measurement device.
73
Evan
AC9TU

Rubens Kamimura
 


ALL

I have uBITX v4 and use it only for FT8 in 40m, but the IRF510 outputs are burned, I am changing them, how do I check if the bias and power settings are correct?
a) I check the tension in the GATE or,
b) the current in the DRAIN?
c) the output power on FT8 at 40m (7,074 MHz), adjusted on VR1?

If I choose to use two IRF520 in place of the IRF510, should I make any changes? any recommendations?
73 from py2pvb
--
Saudações fraternais, 73/51 PY2PVB

Rubens Kamimura
Tel. (18) 3746-8680 ramal 116
Cel. (18) 9-9819-2225 WhatsApp ou (18) 9-9819-2255 


Em ter., 31 de mar. de 2020 às 11:49, flatpickn via Groups.Io <flatpickn=yahoo.com@groups.io> escreveu:

Like some other folks, I have an unbuilt v.4. I've waited to build it until the dust settled over the fix for the harmonics and spurs. I've begun putting it together and realized how hard it is to find good information specific to the v.4. Not because it isn't there but because at the time the fixes and mods were written up they weren't identified as v.4. I'm not saying anyone was lacking in any way, it was the current version and people wrote issues, mods, and fixes. They didn't know that we'd later have a v.6 that was quite different from the v.4. 

Based on a comment by Curt in an earlier post (ubitx 4 - want a fresh start, need guidance) he posted a link with some great uBitx v.4 build information.             https://k3pzn.net/ubitx/

I just wanted to put it here with an easily searchable title for other v.4 builders

 

Vic WA4THR
 

The power supply for these measurements was 13.8v, Tom.

=Vic=

Curt
 

Vic

That v4 looks suspiciously like mine. You can search for Asshar's own words on c81, or tack solder something like 200 pF in parallel,  it might take an iteration but I was happy with the first cap I tried.

Given that the designer chose 470 pF to compensate the transmit chain, and since most v4 are fine as is, I think my suggestion to add a fraction of this value is rather credible. But if someone wants to try 0.01 uF, give it a try. Yes someone here did, and the higher bands  dropped a bunch.

Curt

flatpickn@...
 

Vic,.
    This is with 12v power, correct?

Tom
w9kkq

Vic WA4THR
 

OK, some data. Looks like power out is OK and pretty much as expected for a V4, except the odd drop in CW output on 40m and 17m. Now I am not as sure what to try next as the change at C81 should affect both SSB and CW.

Output through a simple MFJ 822 watt meter into a dummy load, so +/- 10%? SSB by a sustained "AAHHH" into the microphone.

=Vic=

Vic WA4THR
 

My V4 shows a 470pf at C81, and my comment was a reflection of a bad pencil note on my "to do" list. Previous posts had suggested 0.01uf across C81 as improving the low power on 40m, so that's what I should have said. However, I won't be doing anything until I scope it out a bit more. The CW output is pretty low, 3w, while SSB is around 7w. Other bands below 17m are double that. But, as I said, I'll do some more testing to be sure of the scope of the issue which I see others are dealing with, as well. Thanks for the comments.

=Vic=

 

Curt,

I wasn't arguing against your advice.  I merely stated what Allison said worked well for her.  She made other modifications too, but the order is not always clear in the older posts.  In any case, since users' rigs all seem to be a bit different, a few hundred more pF to C81 maybe be perfect, or it may require more or less e.g. experimentation may be necessary.

73,


Mark

Curt
 

Mark

perhaps she made other adjustments, as mine improved greatly with just a few hundred pF added at C81.  please see Asshar's post about C81, I think my adjustment is consistent with what he was recommending for the FEW v4's that have a dip at 40m. 

Curt