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Higher voltage for Bitx40 Final

John Stoole #20077 Wondering how to increase the voltage on the final of the BITX40, I decided to try an up converter, started to search on Ebay and found some very cheap units that seem far to small to do the job (3-5-30V-to-4-0-30V-DC-DC-Booster which are only 50mmx40mm), but are so cheap that I had nothing to loose, I chose a slightly more expensive site in UK so that I did not have to wait for delivery from China, you can see the unit on the link below, http://www.ebay.co.uk/itm/New-3-5-30V-to-4-0-30V-DC-DC-Booster-Converter-Step-Up-Voltage-Regulator-LM2587/272041590361?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D40762%26meid%3D18dbdcfbce2c4a8c95e9904a1da366c2%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D122175575738 Have now installed it and after adjusting the output voltage to 24v and still using the original 100ma bias was surprised to now see that the output is 20watts Have checked the output voltage under load ( Loud Hello) and found that the regulation is excellent went down to 23,5V Certainly worth a go for ?3 /$4 and free postage 73 John mi0dfg
Richard Andrew Knack All Messages By This Member #20080 How much filtering/shielding did you have to put on it? My only experience with a boost converter was a home-made one that I built to make a battery pack replacement for an antique Zenith Transoceanic (the original battery packs produced 9V for the tube filaments and 90V for the B+), but it oscillated and "hashed" so badly that I gave up on it (I didn't know much about filtering at the time; eventually I ended up spending $60 on a professionally made battery replacement unit for that radio that works great). Rich KC8MWG On Friday, January 13, 2017 7:37 AM, John Stoole <jstoole@...> wrote: toggle quoted message Show quoted text Wondering how to increase the voltage on the final of the BITX40, I decided to try an up converter, started to search on Ebay and found some very cheap units that seem far to small to do the job (3-5-30V-to-4-0-30V-DC-DC-Booster which are only 50mmx40mm), but are so cheap that I had nothing to loose, I chose a slightly more expensive site in UK so that I did not have to wait for delivery from China, you can see the unit on the link below, http://www.ebay.co.uk/itm/New-3-5-30V-to-4-0-30V-DC-DC-Booster-Converter-Step-Up-Voltage-Regulator-LM2587/272041590361?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D40762%26meid%3D18dbdcfbce2c4a8c95e9904a1da366c2%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D122175575738 Have now installed it and after adjusting the output voltage to 24v and still using the original 100ma bias was surprised to now see that the output is 20watts Have checked the output voltage under load ( Loud Hello) and found that the regulation is excellent went down to 23,5V Certainly worth a go for ?3 /$4 and free postage 73 John mi0dfg
Jack Purdum #20081 Did you change the heat sink on the final and, if so, what did you use? Jack, W8TEE toggle quoted message Show quoted text From: Richard Andrew Knack via Groups.Io <ihc73scout2@...> To: [email protected] Sent: Friday, January 13, 2017 9:36 AM Subject: Re: [BITX20] Higher voltage for Bitx40 Final How much filtering/shielding did you have to put on it? My only experience with a boost converter was a home-made one that I built to make a battery pack replacement for an antique Zenith Transoceanic (the original battery packs produced 9V for the tube filaments and 90V for the B+), but it oscillated and "hashed" so badly that I gave up on it (I didn't know much about filtering at the time; eventually I ended up spending $60 on a professionally made battery replacement unit for that radio that works great). Rich KC8MWG On Friday, January 13, 2017 7:37 AM, John Stoole <jstoole@...> wrote: Wondering how to increase the voltage on the final of the BITX40, I decided to try an up converter, started to search on Ebay and found some very cheap units that seem far to small to do the job (3-5-30V-to-4-0-30V-DC-DC-Booster which are only 50mmx40mm), but are so cheap that I had nothing to loose, I chose a slightly more expensive site in UK so that I did not have to wait for delivery from China, you can see the unit on the link below, http://www.ebay.co.uk/itm/New-3-5-30V-to-4-0-30V-DC-DC-Booster-Converter-Step-Up-Voltage-Regulator-LM2587/272041590361?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D40762%26meid%3D18dbdcfbce2c4a8c95e9904a1da366c2%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D122175575738 Have now installed it and after adjusting the output voltage to 24v and still using the original 100ma bias was surprised to now see that the output is 20watts Have checked the output voltage under load ( Loud Hello) and found that the regulation is excellent went down to 23,5V Certainly worth a go for ?3 /$4 and free postage 73 John mi0dfg
John Stoole #20082 Hello Rich Well I expected to have a lot of Hash but to my surprise it was completely silent
John Stoole #20083 Hello Jack No I have not changed the heat sink yet, but to be honest I have not had any long QSO's yet, but I did leave the top cover off the case so I could feel the 510 but t only got slightly warm, nothing to worry about , but I will keep an eye on it and do the necessary if needed. John
Frank Dinger , EI7KS All Messages By This Member #20084 No Hash? !?? That is very good to know John Tnx for info Frank ? , GM0CSZ / KN6WH ? ? in IO87AT toggle quoted message Show quoted text On Fri, Jan 13, 2017 at 3:45 PM, John Stoole <jstoole@...> wrote: Hello Rich Well I expected to have a lot of Hash but to my surprise it was completely silent
Richard Andrew Knack All Messages By This Member #20085 That is good news! Is it the same as this one: ? Rich KC8MWG On Friday, January 13, 2017 11:27 AM, "Frank Dinger ,GM0CSZ" <gm0csz@...> wrote: toggle quoted message Show quoted text No Hash? !?? That is very good to know John Tnx for info Frank ? , GM0CSZ / KN6WH ? ? in IO87AT On Fri, Jan 13, 2017 at 3:45 PM, John Stoole <jstoole@...> wrote: Hello Rich Well I expected to have a lot of Hash but to my surprise it was completely silent
Sandeep Lohia All Messages By This Member #20086 > Have now installed it and after adjusting the output voltage to 24v and still using the original 100ma bias was surprised to now see that the output is 20watts > I had also experienced something like this... But 2.5 Watt idle is it enough for 20 watt Linear in class A or Class AB1 ?
John Stoole #20088 Yes Rich That's the one But I paid a bit more to get one from UK, I am surprised how well it works you could not buy the parts for what they charge 73 John
Richard Andrew Knack All Messages By This Member #20093 Just ordered two of them: one for the Bitx20, and one for an SDR I have on the "back burner" for now that requires 15v on the TX circuit. Rich KC8MWG On Friday, January 13, 2017 2:06 PM, John Stoole <jstoole@...> wrote: toggle quoted message Show quoted text Yes Rich That's the one But I paid a bit more to get one from UK, I am surprised how well it works you could not buy the parts for what they charge 73 John
Carl Moser All Messages By This Member #20096 开云体育 I just ordered this one:? It has a higher power rating and is also much cheaper ... 73's? Carl VK2XSM Sent from my iPad
Richard Andrew Knack All Messages By This Member #20097 Wouldn't have worked for me - "Doesn't Post To United States"... :( Rich KC8MWG On Friday, January 13, 2017 4:06 PM, Carl Moser <mail@...> wrote: toggle quoted message Show quoted text I just ordered this one:? It has a higher power rating and is also much cheaper ... 73's? Carl VK2XSM Sent from my iPad
MAc sp9mrn All Messages By This Member #20098 find other seller. ;-) Works very good to circa 22v, over 22v (from 12v supply) mine is very noisy MAc mrn 2017-01-13 22:27 GMT+01:00 Richard Andrew Knack via Groups.Io <ihc73scout2@...>: toggle quoted message Show quoted text Wouldn't have worked for me - "Doesn't Post To United States"... :( Rich KC8MWG On Friday, January 13, 2017 4:06 PM, Carl Moser <mail@...> wrote: I just ordered this one:? It has a higher power rating and is also much cheaper ... 73's? Carl VK2XSM Sent from my iPad
Richard Andrew Knack All Messages By This Member #20099 Well, the other poster said the one he ordered (which I also ended up ordering) are quiet, and they sound like they will work okay for me. THanks! Rich KC8MWG On Friday, January 13, 2017 4:45 PM, MAc B <sp9mrn@...> wrote: toggle quoted message Show quoted text find other seller. ;-) Works very good to circa 22v, over 22v (from 12v supply) mine is very noisy MAc mrn 2017-01-13 22:27 GMT+01:00 Richard Andrew Knack via Groups.Io <ihc73scout2@...>: Wouldn't have worked for me - "Doesn't Post To United States"... :( Rich KC8MWG On Friday, January 13, 2017 4:06 PM, Carl Moser <mail@...> wrote: I just ordered this one:? It has a higher power rating and is also much cheaper ... 73's? Carl VK2XSM Sent from my iPad
Piotr Gocza? All Messages By This Member #20236 Are you sure that's a good idea? Powering PA part from cheap step up converter (RF interferences, voltage peaks and so on) ? Maybe it's better o power PA from decent 24V power supply and add 12V LDO to power rest of receiver with lower voltage? Best regards Piotr
Daniel Corwin All Messages By This Member #20647 Check out this guys. "Note that like most boost regulators, the input power will pass through to the output when the board is disabled, so the ENABLE pin cannot be used to turn off power to the load." What I read there is throw a switch on the enable pin and you can switch between a higher output vs a lower output. Might be a idea. With +12V input it is over 90% up to 2A output supposedly.
Daniel Corwin All Messages By This Member #20662 That would be ideal to use a LDO from a 24v source. But most things amateur radio use 12v-14v especially portable. Using a step-up would make this a decent setup at the cost of battery life. That being said how much current is the PA using when being fully utilized at 24v?
Vic WA4THR All Messages By This Member #41189 Just finished building my BitX40 after playing with the circuit for a few weeks. Early tests on mine suggested that using the small booster I have and raising the PA voltage from around 14 to 24 did seem to increase the power by the square of the voltage ratio, so matching these experiences. Admittedly, I was trying to read this on a 450w dummy load meter, and yelling into the mic, s not very accurate. So this past weekend I did get a QRP wattmeter that could read 30w as full scale and get a better idea of how much I am increasing. However, now when I apply 24v to the final the power output actually drops from 6w to 4w! The only significant cuircuit difference is that I am now running the other 2 power connections (main board and Raduino) through a 7812 regulator, and since it is not getting quite enough to regulate to 12v, it is delivering about 11.5v to those boards, which I assumed was just a bit safer. The voltage booster is not dropping voltage under load, so I am befuddled as to why the power actually drops when I apply the higher voltage. I did recheck the PA bias and raised it up closer to 100ma, but I notice it slowly increases from wherever it is set if I continue to hold the PTT. Any ideas? Perhaps I should short the input to the output of the little 7812 to see if that actually had an effect. =Vic=
Jerry Gaffke All Messages By This Member #41192 11.5v should be fine, make sure it is still 11.5 when PTT is pressed. Quiescent IRF510 drain current changing somewhat as they get warm is normal The drop from 6w to 4w when V+ to the IRF510's is bumped from 12v to 24v is very weird. Have you tried simply switching the IRF510 V+ between the two with exactly the same setup, same instrumentation? Hate to say it, but my first guess would be pilot error. toggle quoted message Show quoted text On Sun, Feb 4, 2018 at 01:10 pm, Vic WA4THR wrote: Just finished building my BitX40 after playing with the circuit for a few weeks. Early tests on mine suggested that using the small booster I have and raising the PA voltage from around 14 to 24 did seem to increase the power by the square of the voltage ratio, so matching these experiences. Admittedly, I was trying to read this on a 450w dummy load meter, and yelling into the mic, s not very accurate. So this past weekend I did get a QRP wattmeter that could read 30w as full scale and get a better idea of how much I am increasing. However, now when I apply 24v to the final the power output actually drops from 6w to 4w! The only significant cuircuit difference is that I am now running the other 2 power connections (main board and Raduino) through a 7812 regulator, and since it is not getting quite enough to regulate to 12v, it is delivering about 11.5v to those boards, which I assumed was just a bit safer. The voltage booster is not dropping voltage under load, so I am befuddled as to why the power actually drops when I apply the higher voltage. I did recheck the PA bias and raised it up closer to 100ma, but I notice it slowly increases from wherever it is set if I continue to hold the PTT. Any ideas? Perhaps I should short the input to the output of the little 7812 to see if that actually had an effect.

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