Topics

BitX40 voltage booster implementation

Vic WA4THR
 

I had planned to include a switchable voltage booster in my BitX40 build to offer a choice of either 5w or 20w when external power permits by providing either 12v or 24v to the PA power line. I plan to use one of these:

https://www.ebay.com/itm/LM2587-DC-DC-Booster-Converter-Step-Up-Voltage-Regulator-3-5-30V-4-0-30V/181847059772?hash=item2a56eded3c:g:B-kAAOSwXf9ZoSKw

I am interested in if others have already implemented this. Some choices I see:
1. Run 12v power to the voltage booster whenever rig power is on, switch the PA to either 12v or 24v. (booster always on, added load?)
2. Wire the output of the booster to the PA power line, but switch 12v to either the PA line or the input of the booster (booster output capable of having voltage applied when input is zero?)

The booster notes just say the output must be higher than the input, but the allowable load specs look OK for SSB.

I am also working on getting 4X the heat sink on the PA transistor.

=Vic=

David Eckhardt <davearea51a@...>
 

It's a switcher.  Beware of severe RFI!!

Dave - W0LEV


Virus-free. www.avast.com

On Wed, Jan 24, 2018 at 8:03 PM, Vic WA4THR via Groups.Io <vhklein@...> wrote:
I had planned to include a switchable voltage booster in my BitX40 build to offer a choice of either 5w or 20w when external power permits by providing either 12v or 24v to the PA power line. I plan to use one of these:

https://www.ebay.com/itm/LM2587-DC-DC-Booster-Converter-Step-Up-Voltage-Regulator-3-5-30V-4-0-30V/181847059772?hash=item2a56eded3c:g:B-kAAOSwXf9ZoSKw

I am interested in if others have already implemented this. Some choices I see:
1. Run 12v power to the voltage booster whenever rig power is on, switch the PA to either 12v or 24v. (booster always on, added load?)
2. Wire the output of the booster to the PA power line, but switch 12v to either the PA line or the input of the booster (booster output capable of having voltage applied when input is zero?)

The booster notes just say the output must be higher than the input, but the allowable load specs look OK for SSB.

I am also working on getting 4X the heat sink on the PA transistor.

=Vic=




--
Dave - WØLEV
Just Let Darwin Work

Clark Martin
 

One thing to watch out for with these type of converters.  I have one where the -input and -output are not wired straight through, it has a current sense resistor in between.  It won’t work for this application as you need to have a common “-“ between input and output.  If you just short them together it willl, at the least, render the current limit inoperative.  At worse, it will mess up the inverting operation and/or regulation.

I’ve only seen this in one converter but it’s worth verifying before you wire it up.

Clark Martin
KK6ISP

On Jan 24, 2018, at 12:03 PM, Vic WA4THR via Groups.Io <vhklein@...> wrote:

I had planned to include a switchable voltage booster in my BitX40 build to offer a choice of either 5w or 20w when external power permits by providing either 12v or 24v to the PA power line. I plan to use one of these:

https://www.ebay.com/itm/LM2587-DC-DC-Booster-Converter-Step-Up-Voltage-Regulator-3-5-30V-4-0-30V/181847059772?hash=item2a56eded3c:g:B-kAAOSwXf9ZoSKw

I am interested in if others have already implemented this. Some choices I see:
1. Run 12v power to the voltage booster whenever rig power is on, switch the PA to either 12v or 24v. (booster always on, added load?)
2. Wire the output of the booster to the PA power line, but switch 12v to either the PA line or the input of the booster (booster output capable of having voltage applied when input is zero?)

The booster notes just say the output must be higher than the input, but the allowable load specs look OK for SSB.

I am also working on getting 4X the heat sink on the PA transistor.

Michael Davis <maddmd818@...>
 

In my experience, the boosters are very noisy. They are sort of inverters.

Sent from Mike's iPad WA1MAD

AA9GG
 

Specs say the part runs at a fixed 100khz.  The LM2587 seems to be a nice part.  Mouser wants $8 a piece, so module is a sweet deal!

On Wed, Jan 24, 2018 at 6:46 PM, Michael Davis <maddmd818@...> wrote:
In my experience, the boosters are very noisy. They are sort of inverters.

Sent from Mike's iPad WA1MAD









--
Paul Mateer, AA9GG
Elan Engineering Corp.
www.elanengr.com
NAQCC 3123, SKCC 4628

Vic WA4THR
 

The input and output negative leads are connected in this unit. I might be able to power it off the 12v TX line, so it would not be powered on receive, but that might be too much current from that circuit. I'll have to test to see if it adds noise or hash on transmit, but was curious if anyone else had implemented this.

=Vic=

AA9GG
 

I believe the 12v part will do 1A on the output, where the 5v part is limited to 300mA

On Wed, Jan 24, 2018 at 9:22 PM, Vic WA4THR via Groups.Io <vhklein@...> wrote:
The input and output negative leads are connected in this unit. I might be able to power it off the 12v TX line, so it would not be powered on receive, but that might be too much current from that circuit. I'll have to test to see if it adds noise or hash on transmit, but was curious if anyone else had implemented this.

=Vic=




--
Paul Mateer, AA9GG
Elan Engineering Corp.
www.elanengr.com
NAQCC 3123, SKCC 4628

vk3xl@...
 

I use one of these in one of my BitX40s.
http://173.214.160.240/item/in-stock-MP9141ES-MP9141/32800753682.html?spm=0.search0305.3.53.619060867Nvj7u&ws_ab_test=searchweb0_0,searchweb201602_0_10130_10615_10617_10616_10618_10059_10534_10313_10084_100031_10083_10547_10624_10546_10623_441_10307_442_10548_10341_10065_10142_10340_10068_10343_10342_10103_10620_10344_10325_10545_10622_10324_10621,searchweb201603_0,ppcSwitch_0&algo_pvid=c90bd8e3-3705-43cd-980a-a810f9ce870c&algo_expid=c90bd8e3-3705-43cd-980a-a810f9ce870c-7
I have it set to 12V and it powers the main part of the circuit board and the raduino. The finals are powered separately but from a common DC connector. This allows me to power the rig from any voltage source from 12V to 28V  without having to make any internal adjustments. The Bucking converter does not introduce any noise that I can hear above the band noise on 40 meters as far as I can tell.

--
Mike VK3XL

Clark Martin
 


Clark Martin
KK6ISP

On Jan 24, 2018, at 7:22 PM, Vic WA4THR via Groups.Io <vhklein@...> wrote:

The input and output negative leads are connected in this unit. I might be able to power it off the 12v TX line, so it would not be powered on receive, but that might be too much current from that circuit. I'll have to test to see if it adds noise or hash on transmit, but was curious if anyone else had implemented this.

Check the idle current, it might not be very much in which case there is little advantage to switching it on with TX.

AA9GG
 

That's the same one I use Mike.....

--
Paul Mateer, AA9GG
Elan Engineering Corp.
www.elanengr.com
NAQCC 3123, SKCC 4628

Vic WA4THR
 

Did some testing today. Running the booster at 14v input and setting the output to 23v I could detect no discernible noise change either on a dummy load or on an antenna. Transmit audio was recorded on a nearby receiver and no added hash or other artifact was noted either. Idle current with no load is perhaps 10ma, so leaving it on all the time the rig is powered is probably no issue. I was reading power into a 450w metered dummy load, so accuracy was not great, but the power level seemed to be up to around 15w (not PEP) on steady AHHH into the mic, as opposed to close to 5 with the standard configuration. Makes sense, (23/14.4)e2 times 6w says I should see 15w in this setup. So this looks like a go, giving nearly an S-unit improvement for little effort.

As an aside, i can tell almost no warming of the PA transistor heat sink during these tests, something I was concerned about. I've been struggling to find a suitable replacement heat sink, keeping with my target of minimizing purchases and using mostly junk-box parts. I do have a potential heat sink that I can use, but it was designed for a different transistor case style so the surface I would use with this TO-220 case is somewhat rough, like a cast finish, and I'm not sure that is a good idea. With the results I've seen is a bigger heat sink really needed? What power level was this one designed for? I only intend to use SSB on this particular rig, too.

=Vic=

Gordon Gibby <ggibby@...>
 

So, some estimations:


Junction to case, IRF510 is 3.5 deg C per watt

Case to greased surface is 0.5 deg C per watt typical

Those heat sinks look similar to  WV-T220-101E  so roughly 13 deg C per watt.


Total thermal resistance to ambient air:   17 deg C per watt.


Assume ambient of 25 (it might be hotter where you are!!!)

Junction spec'd to 175;  for safety figure 140 at the most...


Means maximum dissipation would be around   (140-25) deg C   /  17 deg C per watt or   6.8 watts per device.   


There have been some efficiency figures around here and they were not outstanding....so maybe figure 50% efficiency.   There are two MOSFETS on the ubitx, so you can dissipate a total of about 13.6 W (max) and with 50% effiiciency that would allow the same level of average output.


So....if you're considering uncompressed SSB with a duty cycle of maybe 30-40%, suggests you'd be OK to a peak power output of 1/0.4  x 13.6 =   34 watts  (that is NOT screaming in the mike nor using a compressor, of course)


Different digital modes use different amounts of power.   When my winlink "shifts gears" you can see the average power drop considerably --- like to 50-30% of peak -- but I've read that PSK31 is an 80% duty cycle --- so for PSK31 you'd be restricted back to 17 watts PEP.  


those are all based on available numbers, your mileage may vary!!!


http://www.arrl.org/news/10-tips-for-the-psk31-digital-mode

http://tymkrs.tumblr.com/post/11910142433/ham-radio-averaging-duty-cycle

http://www.ohmite.com/assets/docs/sink_w.pdf?r=false

https://www.digikey.com/product-detail/en/ohmite/WA-T220-101E/WA-T220-101E-ND/2202817

https://www.vishay.com/docs/91015/sihf510.pdf


And I don't know how to estimate the impact of "hot spots" on the MOSFET die.....



Gordon





From: BITX20@groups.io <BITX20@groups.io> on behalf of Vic WA4THR via Groups.Io <vhklein@...>
Sent: Thursday, January 25, 2018 2:34 PM
To: BITX20@groups.io
Subject: Re: [BITX20] BitX40 voltage booster implementation
 
Did some testing today. Running the booster at 14v input and setting the output to 23v I could detect no discernible noise change either on a dummy load or on an antenna. Transmit audio was recorded on a nearby receiver and no added hash or other artifact was noted either. Idle current with no load is perhaps 10ma, so leaving it on all the time the rig is powered is probably no issue. I was reading power into a 450w metered dummy load, so accuracy was not great, but the power level seemed to be up to around 15w (not PEP) on steady AHHH into the mic, as opposed to close to 5 with the standard configuration. Makes sense, (23/14.4)e2 times 6w says I should see 15w in this setup. So this looks like a go, giving nearly an S-unit improvement for little effort.

As an aside, i can tell almost no warming of the PA transistor heat sink during these tests, something I was concerned about. I've been struggling to find a suitable replacement heat sink, keeping with my target of minimizing purchases and using mostly junk-box parts. I do have a potential heat sink that I can use, but it was designed for a different transistor case style so the surface I would use with this TO-220 case is somewhat rough, like a cast finish, and I'm not sure that is a good idea. With the results I've seen is a bigger heat sink really needed? What power level was this one designed for? I only intend to use SSB on this particular rig, too.

=Vic=

Gordon Gibby <ggibby@...>
 

and if the die to heat sink is truly 4 deg C per watt....then the hot point on the heat sink at max dissipation would be at about 110 deg C.    ​that's pretty hot!!!


Probably you want to keep the heat sink below 80 deg C.    (176 deg F)


Maybe attach a thermisor right to the to-220 tab or glue a disassembled cheap thermometer bulb there and mark your "limit" if you plan to push the limits!!


Gordon




From: BITX20@groups.io <BITX20@groups.io> on behalf of Gordon Gibby <ggibby@...>
Sent: Thursday, January 25, 2018 2:59 PM
To: BITX20@groups.io
Subject: Re: [BITX20] BitX40 voltage booster implementation
 

So, some estimations:


Junction to case, IRF510 is 3.5 deg C per watt

Case to greased surface is 0.5 deg C per watt typical

Those heat sinks look similar to  WV-T220-101E  so roughly 13 deg C per watt.


Total thermal resistance to ambient air:   17 deg C per watt.


Assume ambient of 25 (it might be hotter where you are!!!)

Junction spec'd to 175;  for safety figure 140 at the most...


Means maximum dissipation would be around   (140-25) deg C   /  17 deg C per watt or   6.8 watts per device.   


There have been some efficiency figures around here and they were not outstanding....so maybe figure 50% efficiency.   There are two MOSFETS on the ubitx, so you can dissipate a total of about 13.6 W (max) and with 50% effiiciency that would allow the same level of average output.


So....if you're considering uncompressed SSB with a duty cycle of maybe 30-40%, suggests you'd be OK to a peak power output of 1/0.4  x 13.6 =   34 watts  (that is NOT screaming in the mike nor using a compressor, of course)


Different digital modes use different amounts of power.   When my winlink "shifts gears" you can see the average power drop considerably --- like to 50-30% of peak -- but I've read that PSK31 is an 80% duty cycle --- so for PSK31 you'd be restricted back to 17 watts PEP.  


those are all based on available numbers, your mileage may vary!!!


http://www.arrl.org/news/10-tips-for-the-psk31-digital-mode

http://tymkrs.tumblr.com/post/11910142433/ham-radio-averaging-duty-cycle

http://www.ohmite.com/assets/docs/sink_w.pdf?r=false

https://www.digikey.com/product-detail/en/ohmite/WA-T220-101E/WA-T220-101E-ND/2202817

https://www.vishay.com/docs/91015/sihf510.pdf


And I don't know how to estimate the impact of "hot spots" on the MOSFET die.....



Gordon





From: BITX20@groups.io <BITX20@groups.io> on behalf of Vic WA4THR via Groups.Io <vhklein@...>
Sent: Thursday, January 25, 2018 2:34 PM
To: BITX20@groups.io
Subject: Re: [BITX20] BitX40 voltage booster implementation
 
Did some testing today. Running the booster at 14v input and setting the output to 23v I could detect no discernible noise change either on a dummy load or on an antenna. Transmit audio was recorded on a nearby receiver and no added hash or other artifact was noted either. Idle current with no load is perhaps 10ma, so leaving it on all the time the rig is powered is probably no issue. I was reading power into a 450w metered dummy load, so accuracy was not great, but the power level seemed to be up to around 15w (not PEP) on steady AHHH into the mic, as opposed to close to 5 with the standard configuration. Makes sense, (23/14.4)e2 times 6w says I should see 15w in this setup. So this looks like a go, giving nearly an S-unit improvement for little effort.

As an aside, i can tell almost no warming of the PA transistor heat sink during these tests, something I was concerned about. I've been struggling to find a suitable replacement heat sink, keeping with my target of minimizing purchases and using mostly junk-box parts. I do have a potential heat sink that I can use, but it was designed for a different transistor case style so the surface I would use with this TO-220 case is somewhat rough, like a cast finish, and I'm not sure that is a good idea. With the results I've seen is a bigger heat sink really needed? What power level was this one designed for? I only intend to use SSB on this particular rig, too.

=Vic=

Arvo W0VRA
 

On the power side, I'm thinking about a 19V laptop supply and building a small card with 19, 12, and 5V busses.   19V to the PA section, 12 V for the rig in general, and 5 to the SSM2167 card, and maybe to the Raduino.

John T P
 

Dear OM,

when we increase the voltage, proportionally current has to be increased,  so as to maintain output impedence. Hence at 24v,  current should be 2A. such voltage and current will produce lot of heat on final IRF510. 

Hence I would recommend keeping 18v,  1.5A in the final.

Regards 

John T.P., 
VU2JON 
Tharayil House
Sree Ayyappa Road
Kuriachira PO
Thrissur 680 006
Mob : 8807007933
India 

On Jan 26, 2018 2:06 AM, "Arvo KD9HLC via Groups.Io" <arvopl=yahoo.com@groups.io> wrote:
On the power side, I'm thinking about a 19V laptop supply and building a small card with 19, 12, and 5V busses.   19V to the PA section, 12 V for the rig in general, and 5 to the SSM2167 card, and maybe to the Raduino.

Gordon Gibby <ggibby@...>
 

"when we increase the voltage, proportionally current has to be increased,  so as to maintain output impedence. Hence at 24v,  current should be 2A. such voltage and current will produce lot of heat on final IRF510. "


This  raises a question to me.   Is it guaranteed that the impedance remains the  same?   Or it is the TRANSONDUCTANCE of the IRF510 that remains unchanged?   

Has this been checked experimentally in this transmitter?






From: BITX20@groups.io <BITX20@groups.io> on behalf of John T P <tpjohn@...>
Sent: Thursday, January 25, 2018 6:26 PM
To: BITX20@groups.io
Subject: Re: [BITX20] BitX40 voltage booster implementation
 
Dear OM,

when we increase the voltage, proportionally current has to be increased,  so as to maintain output impedence. Hence at 24v,  current should be 2A. such voltage and current will produce lot of heat on final IRF510. 

Hence I would recommend keeping 18v,  1.5A in the final.

Regards 

John T.P., 
VU2JON 
Tharayil House
Sree Ayyappa Road
Kuriachira PO
Thrissur 680 006
Mob : 8807007933
India 

On Jan 26, 2018 2:06 AM, "Arvo KD9HLC via Groups.Io" <arvopl=yahoo.com@groups.io> wrote:
On the power side, I'm thinking about a 19V laptop supply and building a small card with 19, 12, and 5V busses.   19V to the PA section, 12 V for the rig in general, and 5 to the SSM2167 card, and maybe to the Raduino.