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On Mon, May 1, 2017 at 2:09 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: Also, that 130C calculation assumes you have been transmitting that 20 Watts long enough for things to reach equilibrium.? If the tab is still slowly heating beyond 60C, that means the die is much hotter than 130C. The IRF510 is spec'd for a junction operating temp of 175C max, but ?I think you might be pushing dangerously close to that.? Heatsink shouldn't get much more than lukewarm.? Those insisting on lots of power might do well to borrow the design of the uBitx final: ?? ? building just the push-pull 2n2219 and IRF510 stages.? The two single npn stages preceding that in the uBitx design can be adapted from the existing Bitx40 stages.
On Mon, May 1, 2017 at 10:57 am, Jerry Gaffke wrote:
I'd ?say 60C at the heatsink is dangerously hot.? Time to stock up an extra IRF510's, you will likely need them. The transfer of heat from die to tab is not very efficient on the IRF510, it is spec'd at 3.5 degrees C per Watt.? Assume you are transmitting 20 Watts at 50% efficiency.? So the IRF510 die is dissipating 20 Watts, and the die itself is 60C + 3.5*20 ?= ?130C. ? That's assuming the tab of the IRF510 has perfect heat transfer to the heatsink where you mesured your 60C. ? Jerry, KE7ER
/g/BITX20/message/24339
On Mon, May 1, 2017 at 07:59 am, Steve Greer wrote:
LOL I actually use a computer heatsink from a CPU it's like 3x2 and has 20 or so fins and I have a cpu fan attached to it's back.? I have push this thing to the max and the hottest I have had it on JT65 was 60c and was plenty cool by next TX.
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Funny you mentioned that because I started a thread about that exact subject and looking for some input about it.? I think it would be rather easy to do.? Please see other thread
On Mon, May 1, 2017 at 2:09 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: Also, that 130C calculation assumes you have been transmitting that 20 Watts long enough for things to reach equilibrium.? If the tab is still slowly heating beyond 60C, that means the die is much hotter than 130C. The IRF510 is spec'd for a junction operating temp of 175C max, but ?I think you might be pushing dangerously close to that.? Heatsink shouldn't get much more than lukewarm.? Those insisting on lots of power might do well to borrow the design of the uBitx final: ?? ? building just the push-pull 2n2219 and IRF510 stages.? The two single npn stages preceding that in the uBitx design can be adapted from the existing Bitx40 stages.
On Mon, May 1, 2017 at 10:57 am, Jerry Gaffke wrote:
I'd ?say 60C at the heatsink is dangerously hot.? Time to stock up an extra IRF510's, you will likely need them. The transfer of heat from die to tab is not very efficient on the IRF510, it is spec'd at 3.5 degrees C per Watt.? Assume you are transmitting 20 Watts at 50% efficiency.? So the IRF510 die is dissipating 20 Watts, and the die itself is 60C + 3.5*20 ?= ?130C. ? That's assuming the tab of the IRF510 has perfect heat transfer to the heatsink where you mesured your 60C. ? Jerry, KE7ER
/g/BITX20/message/24339
On Mon, May 1, 2017 at 07:59 am, Steve Greer wrote:
LOL I actually use a computer heatsink from a CPU it's like 3x2 and has 20 or so fins and I have a cpu fan attached to it's back.? I have push this thing to the max and the hottest I have had it on JT65 was 60c and was plenty cool by next TX.
?
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Re: European Bitx Net - Tonight (1 May) 1900UTC 7175 kHz
I'll try to be there also.
CU, 73's Adi YO2LIW
On Monday, May 1, 2017 7:59 PM, Allard PE1NWL <pe1nwl@...> wrote:
Good idea! I?ll be there at 1900 UTC (2100 Central European Time).
The only problem might be that we have interference from a strong image from Radio Romania or Voice of China. I seem to remember that this was around 7175 at 1900UTC (not quite sure). Ah well, let's try, we can alway move to another frequency if necessary. 73, Allard PE1NWL
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Also, that 130C calculation assumes you have been transmitting that 20 Watts long enough for things to reach equilibrium. ?If the tab is still slowly heating beyond 60C, that means the die is much hotter than 130C. The IRF510 is spec'd for a junction operating temp of 175C max, but ?I think you might be pushing dangerously close to that. ?Heatsink shouldn't get much more than lukewarm. ?Those insisting on lots of power might do well to borrow the design of the uBitx final: ?? ? building just the push-pull 2n2219 and IRF510 stages. ?The two single npn stages preceding that in the uBitx design can be adapted from the existing Bitx40 stages.
On Mon, May 1, 2017 at 10:57 am, Jerry Gaffke wrote:
I'd ?say 60C at the heatsink is dangerously hot. ?Time to stock up an extra IRF510's, you will likely need them. The transfer of heat from die to tab is not very efficient on the IRF510, it is spec'd at 3.5 degrees C per Watt. ?Assume you are transmitting 20 Watts at 50% efficiency. ?So the IRF510 die is dissipating 20 Watts, and the die itself is 60C + 3.5*20 ?= ?130C. ? That's assuming the tab of the IRF510 has perfect heat transfer to the heatsink where you mesured your 60C. ? Jerry, KE7ER
/g/BITX20/message/24339
On Mon, May 1, 2017 at 07:59 am, Steve Greer wrote:
LOL I actually use a computer heatsink from a CPU it's like 3x2 and has 20 or so fins and I have a cpu fan attached to it's back.? I have push this thing to the max and the hottest I have had it on JT65 was 60c and was plenty cool by next TX.
?
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That was on the face of the fet and they are rated 170c I have a few extras we don't learn limits without a little black smoke.
On Mon, May 1, 2017 at 1:57 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: I'd ?say 60C at the heatsink is dangerously hot.? Time to stock up an extra IRF510's, you will likely need them. The transfer of heat from die to tab is not very efficient on the IRF510, it is spec'd at 3.5 degrees C per Watt.? Assume you are transmitting 20 Watts at 50% efficiency.? So the IRF510 die is dissipating 20 Watts, and the die itself is 60C + 3.5*20 ?= ?130C. ? That's assuming the tab of the IRF510 has perfect heat transfer to the heatsink where you mesured your 60C. ? Jerry, KE7ER
/g/BITX20/message/24339 On Mon, May 1, 2017 at 07:59 am, Steve Greer wrote:
LOL I actually use a computer heatsink from a CPU it's like 3x2 and has 20 or so fins and I have a cpu fan attached to it's back.? I have push this thing to the max and the hottest I have had it on JT65 was 60c and was plenty cool by next TX.
?
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I'd ?say 60C at the heatsink is dangerously hot. ?Time to stock up an extra IRF510's, you will likely need them. The transfer of heat from die to tab is not very efficient on the IRF510, it is spec'd at 3.5 degrees C per Watt. ?Assume you are transmitting 20 Watts at 50% efficiency. ?So the IRF510 die is dissipating 20 Watts, and the die itself is 60C + 3.5*20 ?= ?130C. ? That's assuming the tab of the IRF510 has perfect heat transfer to the heatsink where you mesured your 60C. ? Jerry, KE7ER
/g/BITX20/message/24339
On Mon, May 1, 2017 at 07:59 am, Steve Greer wrote:
LOL I actually use a computer heatsink from a CPU it's like 3x2 and has 20 or so fins and I have a cpu fan attached to it's back.? I have push this thing to the max and the hottest I have had it on JT65 was 60c and was plenty cool by next TX.
?
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Re: R15 and ADE-1 mixer getting very hot
Hi Sarma, I found it, thank you very much. 73 Gian I7SWX
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Some friends have received 4 ohms speakers by mistake instead of standard 8 ohms ?if you are one of those,then kindly send me your pay pal transaction number, so that we can send a free replacement. Speaker is Milton Blue color 2 inch size marked 4 .? Apologies for the mistake. best of 73s Sunil vu3sua ?
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Re: European Bitx Net - Tonight (1 May) 1900UTC 7175 kHz
Good idea! I?ll be there at 1900 UTC (2100 Central European Time).
The only problem might be that we have interference from a strong image from Radio Romania or Voice of China. I seem to remember that this was around 7175 at 1900UTC (not quite sure). Ah well, let's try, we can alway move to another frequency if necessary. 73, Allard PE1NWL
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Re: Farhan to attend FDIM
Farhan,? ? You stand among the giants in the QRP world!? Very happy to hear you will be at FDIM!? Would love a photo op!? As would others I am certain!? I wish you were speaking at the Thursday conference!? Would love to hear what you have to say!?
? Have a safe trip my friend!? Hope to see you and Hans in Dayton!?
73 de Seth - W8FG?
On Sun, Apr 30, 2017 at 9:28 PM Ashhar Farhan < farhanbox@...> wrote: Dale, I haven't applied for a table. My own idea was to go around other tables and catch up with folks myself. I will be hanging around with G0UPL, Hans. I am hoping to catch up with a few folks like roy w7el, jerry Buxton n2yo etc. No particular sked though. I should probably work one out. - f
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VE3UUV,Mark Ontario Canada
Been calling CQ from Ontario Canada since 9:10but no return.
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I currently use 24 volt yes I want More Power.? I come from the Home Improvement Generation.. Tim The Tool Man Taylor "More Power" ?--Insert Grunt Here-- ?
On Mon, May 1, 2017 at 11:13 AM, OZ9AEW <madsen1960@...> wrote: do you need more then about 20Watt ?? because that is what a single IRF510 can deliver with a 24Volt PSU, and of course only 12 Volt for the rest of your Bitx40
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do you need more then about 20Watt ?? because that is what a single IRF510 can deliver with a 24Volt PSU, and of course only 12 Volt for the rest of your Bitx40
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LOL I actually use a computer heatsink from a CPU it's like 3x2 and has 20 or so fins and I have a cpu fan attached to it's back.? I have push this thing to the max and the hottest I have had it on JT65 was 60c and was plenty cool by next TX.
On Mon, May 1, 2017 at 10:52 AM, KC8WBK via Groups.Io <cruisenewsnet@...> wrote: What type of heat sink are you using?
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So as I investigate this some more it appears this may be easier than I had thought.? But I really don't know, I'm just a new Ham and trying to apply some logic and I have no real electronics schooling, so bear with me... ?at c133 and r135 I could tap with 10R and .1uf like the ubitx shows and flip t6 around at the regulator then move to small breakout board for dual 2n2219 second preamp stage and coil out like t10 on the ubitx schematic tap out of the regulator to feed the dual irf510's then out to choke and coil and tie back in at t7 flipped as well.? Sounds like a bit of work but I think it can be done.? I would like the input of any of the engineers that follow the post, and anyone else who cares to input. ?thanks 73 km4ous
On Mon, May 1, 2017 at 10:17 AM, Steve Greer <km4ous@...> wrote: More power???? I was looking at the schematic at the PA circuit and it appears that it was wired with a thought of dual IRF's in the future.? What got me thinking was looking at the ubitx that has dual IRF's and comparing the 2, the coils have the winding's with unused taps, could one of the electronic engineers draw something up that we could mod a Push Pull dual IRF's.? I really don't know how to go about it myself but it looks possible.?maybe???
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What type of heat sink are you using?
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More power??? ?I was looking at the schematic at the PA circuit and it appears that it was wired with a thought of dual IRF's in the future. ?What got me thinking was looking at the ubitx that has dual IRF's and comparing the 2, the coils have the winding's with unused taps, could one of the electronic engineers draw something up that we could mod a Push Pull dual IRF's. ?I really don't know how to go about it myself but it looks possible.?maybe???
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I use 3 PSU total I use a WII power supply to power the radio itself and I use 2 xbox 360 power bricks in series for 24 Volts to the PA.? The WII PSU is 10 amps rated and the xbox supplies are 16 amps each so 32 amps total.? I get about 15-20 watts out on 40 and and 30 watts out on 80 and 10 watts out on 30M.? Antenna Antenna Antenna.? What are you using for an antenna?? I often hear about Hams buying $1000+ radios and Kw amps but if your antenna is garage it's just a waste, the antenna should be one of the largest investments in a station.
On Mon, May 1, 2017 at 9:52 AM, KC8WBK via Groups.Io <cruisenewsnet@...> wrote: I am wondering what others are using for power supplies. I have received signal reports of weak signal, and there was a comment that it might be a lack of power during transmission. I am using a wall wart, rated at 12V, 1.65 amps. I went to the thrift store and got a laptop power supply, rated at 20V, 2.25 amps. I measured 20.6V at no load. This power supply is now connected to PA power.? I have replaced the heat sink with one about twice the mass, 13 grams vs. 6 grams, and not quite twice the size of the original.? It seems to pass the initial smoke test. I am hoping that this combination of two power supplies resolves the weak signal problem.? There are other options, such as a lead acid battery on a charger, or my big 20 amp 12V power supply.
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I am wondering what others are using for power supplies. I have received signal reports of weak signal, and there was a comment that it might be a lack of power during transmission. I am using a wall wart, rated at 12V, 1.65 amps. I went to the thrift store and got a laptop power supply, rated at 20V, 2.25 amps. I measured 20.6V at no load. This power supply is now connected to PA power.? I have replaced the heat sink with one about twice the mass, 13 grams vs. 6 grams, and not quite twice the size of the original.? It seems to pass the initial smoke test. I am hoping that this combination of two power supplies resolves the weak signal problem.? There are other options, such as a lead acid battery on a charger, or my big 20 amp 12V power supply.
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Re: Simple audio muting circuit
Tried this tonight and it works!
Only small issue is that when the volume is on full there is an audio oscillation. Its right at the end of the pot though so not a problem because i never turn it up full volume. There is also some digital noise from the raduino leaking through the power supply i think that comes through the audio whilst the cap on the receiver power supply still has some charge. Hoping the click power supply mod will get rid of it.
A massive improvement overall and i can now use my BITX40 witb headphones as i found the ptt pop literally painful without this mod. Also tried the diode across k1 by itself first. There was no change to the ptt pop.
Thanks and 73 John.
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Giancarlo - I7SWX
Sunil Lakhani
Allard PE1NWL
Seth Lavinder W8FG