Topics

80/40 power increase if possible

pete torrance <wayfound2000@...>
 

Hi 
Ubitx V3 here. I am only really interested in using 80 and 40m SSB and I am getting around 10W on 40 and 12W on 80. All fine and dandy but would like to increase this if possible. Ive seen loads of posts about increasing the PA voltage but am a bit confused about where the breaks should be to isolate the PA supply V ? Considering some of the other component change suggestions re: extra power out but find these days that my fumbly fingers don't match well with tiny components Verses soldering iron! Any expert advice would be really appreciated!
Have fun!
Pete G4HAK

Evan Hand
 

Pete,

I do not have a v3, however I do have both a v4 and v5.  All three of the schematics and the two boards that I have used a 3 pin connector with Black, Brown, and Red wires.  The Black is common, the Red is for the mainboard, and the brown is for just the PA.    Simply separate the Brown wire and connect the higher voltage to it.  I would recommend that you keep the voltage to the mainboard at 12 volts, through a voltage regulator or separate power supply.

I hope this helps, and please let us know how it goes.

73
Evan
AC9TU

pete torrance <wayfound2000@...>
 

Thanks Evan. Yes I see it now on the diagram. How did I miss that!  Many thanks. Yes will certainly report back with the results.
73
Pete G4HAK

On Wednesday, 22 April 2020, 15:02:57 BST, Evan Hand <elhandjr@...> wrote:


Pete,

I do not have a v3, however I do have both a v4 and v5.  All three of the schematics and the two boards that I have used a 3 pin connector with Black, Brown, and Red wires.  The Black is common, the Red is for the mainboard, and the brown is for just the PA.    Simply separate the Brown wire and connect the higher voltage to it.  I would recommend that you keep the voltage to the mainboard at 12 volts, through a voltage regulator or separate power supply.

I hope this helps, and please let us know how it goes.

73
Evan
AC9TU

Evan Hand
 

Pete,
Forgot to mention that you will need to increase the heat transfer capability of the finals.  That can be a fan, larger heatsinks, or both.  You should also rebias the two IRF510s.

Good Luck with the tests!
73
Evan
AC9TU

pete torrance <wayfound2000@...>
 


Evan. Ahh yes I have a largish heatsink already fitted which should be up to the task.  Any idea of roughly how much bias current would be appropriate for say 24V Rail?

Pete

On Wednesday, 22 April 2020, 17:56:07 BST, Evan Hand <elhandjr@...> wrote:


Pete,
Forgot to mention that you will need to increase the heat transfer capability of the finals.  That can be a fan, larger heatsinks, or both.  You should also rebias the two IRF510s.

Good Luck with the tests!
73
Evan
AC9TU

Evan Hand
 

Understand that I am not an RF engineer, however, what I have read is that the bias would be dependant on the implementation.  Per this thread:
https://groups.io/g/BITX20/message/73757
The bias for an IRF510 would still be in the 50 to 150 ma range, so I would start with 100 ma for each of the devices.

Another watch out:  The drains of the IRF510 is connected to the heatsink tab.  Be sure to use insulators if you are going to mount them on a common heatsink, or if the larger heatsinks have a chance of touching another surface.  I would use them as the thermal resistance is not that high.

73
Evan
AC9TU

pete torrance <wayfound2000@...>
 

Ok that's good thankyou. great group this!
73



Sent from my Samsung Galaxy A3 2016 - powered by Three

-------- Original message --------
From: Evan Hand <elhandjr@...>
Date: 22/04/2020 19:19 (GMT+00:00)
To: BITX20@groups.io
Subject: Re: [BITX20] 80/40 power increase if possible

Understand that I am not an RF engineer, however, what I have read is that the bias would be dependant on the implementation.  Per this thread:
https://groups.io/g/BITX20/message/73757
The bias for an IRF510 would still be in the 50 to 150 ma range, so I would start with 100 ma for each of the devices.

Another watch out:  The drains of the IRF510 is connected to the heatsink tab.  Be sure to use insulators if you are going to mount them on a common heatsink, or if the larger heatsinks have a chance of touching another surface.  I would use them as the thermal resistance is not that high.

73
Evan
AC9TU

Rubens Kamimura
 

Pete G4HAK, good night.

You have already observed the value of C81 and if VR-1, it is at the limit switch (counterclockwise). See in previous posts related to the subject. I believe that in order to give your IRF510's a vitamin (testosterone), you will need to readjust your IBF of the IRF510 to the new voltage + B PA-PWR. I burned several IRF510s by making new IBias adjustments for the IRF510s. I suggest installing a Step up (13.8VDC_24VDC booster converter), placing a 24VDC @ 70W lamp in series to adjust the Ibias of the IRF510, this way you will limit the current and burning of the PA transistors. Note that the conductors from the source to the PA PWR connector are thin. If you choose to put more power, change the conductors and review the connections, because mine melted with the high current. The transistors will heat up a little more, put thermal paste on the transistors of the PA (between the transistor and heat sink), install a fan also for warranty.
good luck. 73 by Rubens PY2PVB.

Em qua., 22 de abr. de 2020 às 10:51, pete torrance via groups.io <wayfound2000=yahoo.com@groups.io> escreveu:

Hi 
Ubitx V3 here. I am only really interested in using 80 and 40m SSB and I am getting around 10W on 40 and 12W on 80. All fine and dandy but would like to increase this if possible. Ive seen loads of posts about increasing the PA voltage but am a bit confused about where the breaks should be to isolate the PA supply V ? Considering some of the other component change suggestions re: extra power out but find these days that my fumbly fingers don't match well with tiny components Verses soldering iron! Any expert advice would be really appreciated!
Have fun!
Pete G4HAK

Gary Anderson
 

To add to Evan's advice,
RV2 and RV3 that set the bias for the IRF510's are wired counter-intuitive to most.  But it is well documented.
https://www.hfsignals.com/index.php/ubitx-tuneup/ 

Rgds,
Gary

pete torrance <wayfound2000@...>
 

Hi gary
Thanks for the info. so easy to think clockwise is more! great transceiver and great learning curve. pure amateur radio!
73
Pete 



Sent from my Samsung Galaxy A3 2016 - powered by Three

pete torrance <wayfound2000@...>
 

Yep thanks Rubens...for the tips and sharing your experiences.  thank goodness the PA transistors don't cost too much to replace.
73
pete



Sent from my Samsung Galaxy A3 2016 - powered by Three

-------- Original message --------
From: Rubens Kamimura <rubens.kamimura@...>
Date: 22/04/2020 19:46 (GMT+00:00)
To: BITX20@groups.io
Subject: Re: [BITX20] 80/40 power increase if possible

Pete G4HAK, good night.

You have already observed the value of C81 and if VR-1, it is at the limit switch (counterclockwise). See in previous posts related to the subject. I believe that in order to give your IRF510's a vitamin (testosterone), you will need to readjust your IBF of the IRF510 to the new voltage + B PA-PWR. I burned several IRF510s by making new IBias adjustments for the IRF510s. I suggest installing a Step up (13.8VDC_24VDC booster converter), placing a 24VDC @ 70W lamp in series to adjust the Ibias of the IRF510, this way you will limit the current and burning of the PA transistors. Note that the conductors from the source to the PA PWR connector are thin. If you choose to put more power, change the conductors and review the connections, because mine melted with the high current. The transistors will heat up a little more, put thermal paste on the transistors of the PA (between the transistor and heat sink), install a fan also for warranty.
good luck. 73 by Rubens PY2PVB.

Em qua., 22 de abr. de 2020 às 10:51, pete torrance via groups.io <wayfound2000=yahoo.com@groups.io> escreveu:
Hi 
Ubitx V3 here. I am only really interested in using 80 and 40m SSB and I am getting around 10W on 40 and 12W on 80. All fine and dandy but would like to increase this if possible. Ive seen loads of posts about increasing the PA voltage but am a bit confused about where the breaks should be to isolate the PA supply V ? Considering some of the other component change suggestions re: extra power out but find these days that my fumbly fingers don't match well with tiny components Verses soldering iron! Any expert advice would be really appreciated!
Have fun!
Pete G4HAK

Lawrence Galea
 

Hi
Since your mbitx is working ok, why not try an external amplifier?
Regards
Lawrence

On Wed, Apr 22, 2020 at 11:53 PM pete torrance via groups.io <wayfound2000=yahoo.com@groups.io> wrote:
Yep thanks Rubens...for the tips and sharing your experiences.  thank goodness the PA transistors don't cost too much to replace.
73
pete



Sent from my Samsung Galaxy A3 2016 - powered by Three

-------- Original message --------
From: Rubens Kamimura <rubens.kamimura@...>
Date: 22/04/2020 19:46 (GMT+00:00)
Subject: Re: [BITX20] 80/40 power increase if possible

Pete G4HAK, good night.

You have already observed the value of C81 and if VR-1, it is at the limit switch (counterclockwise). See in previous posts related to the subject. I believe that in order to give your IRF510's a vitamin (testosterone), you will need to readjust your IBF of the IRF510 to the new voltage + B PA-PWR. I burned several IRF510s by making new IBias adjustments for the IRF510s. I suggest installing a Step up (13.8VDC_24VDC booster converter), placing a 24VDC @ 70W lamp in series to adjust the Ibias of the IRF510, this way you will limit the current and burning of the PA transistors. Note that the conductors from the source to the PA PWR connector are thin. If you choose to put more power, change the conductors and review the connections, because mine melted with the high current. The transistors will heat up a little more, put thermal paste on the transistors of the PA (between the transistor and heat sink), install a fan also for warranty.
good luck. 73 by Rubens PY2PVB.

Em qua., 22 de abr. de 2020 às 10:51, pete torrance via groups.io <wayfound2000=yahoo.com@groups.io> escreveu:
Hi 
Ubitx V3 here. I am only really interested in using 80 and 40m SSB and I am getting around 10W on 40 and 12W on 80. All fine and dandy but would like to increase this if possible. Ive seen loads of posts about increasing the PA voltage but am a bit confused about where the breaks should be to isolate the PA supply V ? Considering some of the other component change suggestions re: extra power out but find these days that my fumbly fingers don't match well with tiny components Verses soldering iron! Any expert advice would be really appreciated!
Have fun!
Pete G4HAK

pete torrance <wayfound2000@...>
 

Hi Laurence
nice to hear from you. could do that but only looking for about 20w so ext amp prob a bit of a waste plus more leads etc. plus I like fiddling and experimenting. nice thought though.
Take care
Pete G4HAK



Sent from my Samsung Galaxy A3 2016 - powered by Three

-------- Original message --------
From: Lawrence Galea <9h1avlaw@...>
Date: 23/04/2020 13:41 (GMT+00:00)
To: BITX20@groups.io
Subject: Re: [BITX20] 80/40 power increase if possible

Hi
Since your mbitx is working ok, why not try an external amplifier?
Regards
Lawrence

On Wed, Apr 22, 2020 at 11:53 PM pete torrance via groups.io <wayfound2000=yahoo.com@groups.io> wrote:
Yep thanks Rubens...for the tips and sharing your experiences.  thank goodness the PA transistors don't cost too much to replace.
73
pete



Sent from my Samsung Galaxy A3 2016 - powered by Three

-------- Original message --------
From: Rubens Kamimura <rubens.kamimura@...>
Date: 22/04/2020 19:46 (GMT+00:00)
Subject: Re: [BITX20] 80/40 power increase if possible

Pete G4HAK, good night.

You have already observed the value of C81 and if VR-1, it is at the limit switch (counterclockwise). See in previous posts related to the subject. I believe that in order to give your IRF510's a vitamin (testosterone), you will need to readjust your IBF of the IRF510 to the new voltage + B PA-PWR. I burned several IRF510s by making new IBias adjustments for the IRF510s. I suggest installing a Step up (13.8VDC_24VDC booster converter), placing a 24VDC @ 70W lamp in series to adjust the Ibias of the IRF510, this way you will limit the current and burning of the PA transistors. Note that the conductors from the source to the PA PWR connector are thin. If you choose to put more power, change the conductors and review the connections, because mine melted with the high current. The transistors will heat up a little more, put thermal paste on the transistors of the PA (between the transistor and heat sink), install a fan also for warranty.
good luck. 73 by Rubens PY2PVB.

Em qua., 22 de abr. de 2020 às 10:51, pete torrance via groups.io <wayfound2000=yahoo.com@groups.io> escreveu:
Hi 
Ubitx V3 here. I am only really interested in using 80 and 40m SSB and I am getting around 10W on 40 and 12W on 80. All fine and dandy but would like to increase this if possible. Ive seen loads of posts about increasing the PA voltage but am a bit confused about where the breaks should be to isolate the PA supply V ? Considering some of the other component change suggestions re: extra power out but find these days that my fumbly fingers don't match well with tiny components Verses soldering iron! Any expert advice would be really appreciated!
Have fun!
Pete G4HAK

ajparent1/kb1gmx <kb1gmx@...>
 

If your going to run at 24V...

Bias set at 24V is still 100ma.
Make sure you have a lot of cooling, a fan is required.
Insure you maintain the SWR as low.
Keep a spare set of IRF510s.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

pete torrance <wayfound2000@...>
 

hi Allison
thankyou. got a small very quiet pc fan. will keep things nice and cool. IRF510's on order...just in case ! 
 73
pete