Topics

uBitx v.4 build information

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



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



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 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
 

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
 

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