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On my just-completed unit, with a 12 V supply (11.6 V on the collector of Q6) I am seeing 1.2 W output (22 V p-p into 50Ω) on key down, rising to 1.6 W after ~ 10 sec (25 V p-p). ?I removed C29, the dc blocking cap at the input to the filter and fed my signal generator (AD9850-based homebrew) into the filter at that point and measured the output into a 50Ω load at the input to my TEK 2247A scope. ?I saw a loss of 2.32 dB at 14.000 MHz, 2.49 dB at 14.100, and 2.56 dB T 14.200. ?This seems excessive. ?1.5 W is only a half S unit below the expected 3 W, but with a report of RST 319 it could be important! ?Guess I need to work on the lpf a bit.
Ben ?- ?K0IKR
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Hi DL3HRT, your name would be good. So why take 1 turn from L1 and L2 but not L3, L3 is part of the LPF also, just curious. I would think that if L2 is high in inductance and attenuating the output that L3 would be the same. I have the same low output on my 20 meter QCX, (1.6 watts), so I would like a more definitive solution to figure out exactly what to do as I don’t want to hack my board up experimenting with different things. Thanks for your help.
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On Nov 1, 2017, at 2:37 AM, DL3HRT < dl3hrt@...> wrote: Hi all, I did some optimization on the low pass filter. Finally I had to remove 1 turn from L2 and 1 turn from L3. Power output is as expected now. I recorded some thermal images with my Seek Reveal Pro. The QCX was running in WSPR-beacon mode with almost continuous transmission. The BS170 heated up to almost 100°C. I think that is safe without heatsink. <DL3HRT _ BS170 heating.PNG> <DL3HRT _ 20m_QCX _ output power.png>
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Hi all,
I did some optimization on the low pass filter. Finally I had to remove 1 turn from L2 and 1 turn from L3. Power output is as expected now.
I recorded some thermal images with my Seek Reveal Pro. The QCX was running in WSPR-beacon mode with almost continuous transmission. The BS170 heated up to almost 100°C. I think that is safe without heatsink.
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Thanks, Glenn.
Lee, w0vt
On 10/26/2017 4:05 AM, Glenn S wrote:
Hi Lee,
I took a turn off both L2 and L3, so L3 is 15T and L2 is 16T now.?
It didn't make a big difference, but I noticed that with the
original turns, the windings had to be spread right out on L2 and
L3.??
Cheers,
Glenn VK3YY.
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Hi Lee,
I took a turn off both L2 and L3, so L3 is 15T and L2 is 16T now.? It didn't make a big difference, but I noticed that with the original turns, the windings had to be spread right out on L2 and L3.??
Cheers,
Glenn VK3YY.
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Glenn, Sure would like to know if you removed a turn or two. Thanks for the cap confirmation.
Lee, w0vt
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On 10/25/2017 8:45 PM, Glenn S wrote: Hi Lee,
Yes, I used the same values of cap in the LPF as original. I had an ATC ceramic designers kit on hand (200V), so just used those caps for replacements.? I may have taken a turn off one of the toroids, as well will have a look tonight.
Cheers,
Glenn VK3YY.
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Hi Lee,
Yes, I used the same values of cap in the LPF as original.? I had an ATC ceramic designers kit on hand (200V), so just used those caps for replacements.? I may have taken a turn off one of the toroids, as well will have a look tonight.
Cheers, Glenn VK3YY.
On 26 October 2017 at 10:33, Leland L. Bahr <l@...> wrote: Glenn,
You said you replaced the two 390pf caps in the pi net.? I take it you used the same value of 390pf caps in the replacements.? Is that correct?? If that is the case I am going to try a couple 390pf Silver Mica caps as I have some of these. I've seen the multilayer small caps used many times in 1 watt rigs, but they make me nervous,? especially if they are not COG types. (Especially if they are of the 50 volt variety rather then 100 volt caps.)? Then too I wonder about SWR.? I realize we don't want any here but it happens especially when using a tuner to tune out reactance.? I know a 300 volt silver mica may be overkill, but I am thinking they would be trouble free for a very long time. Certainly not marginal!? I checked and they will clear the display if deployed.
Lee, w0vt
Alchemy in Action
I am getting 4 watts out at 13.8V on 20 metres as measured on a Bird wattmeter.
Cheers,
Glenn VK3YY.
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Glenn,
You said you replaced the two 390pf caps in the pi net.? I take it you used the same value of 390pf caps in the replacements.? Is that correct?? If that is the case I am going to try a couple 390pf Silver Mica caps as I have some of these. I've seen the multilayer small caps used many times in 1 watt rigs, but they make me nervous,? especially if they are not COG types. (Especially if they are of the 50 volt variety rather then 100 volt caps.)? Then too I wonder about SWR.? I realize we don't want any here but it happens especially when using a tuner to tune out reactance.? I know a 300 volt silver mica may be overkill, but I am thinking they would be trouble free for a very long time. Certainly not marginal!? I checked and they will clear the display if deployed.
Lee, w0vt
Alchemy in Action
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I am getting 4 watts out at 13.8V on 20 metres as measured on a Bird wattmeter.
Cheers,
Glenn VK3YY.
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Thanks Glenn,
Looks like you found the problem, now to find some suitable caps.
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On Oct 25, 2017, at 3:24 PM, Glenn S < glenn.vk3yy@...> wrote: Hi Joel,
I am getting 4 watts out at 13.8V on 20 metres as measured on a Bird wattmeter.?
Cheers, Glenn VK3YY.
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Hi Joel,
I am getting 4 watts out at 13.8V on 20 metres as measured on a Bird wattmeter.?
Cheers, Glenn VK3YY.
On 26 October 2017 at 03:33, Joel Caulkins <caulktel@...> wrote: Thanks Carlos and Choke, I guess this might be normal for 20 meters. I can’t fix it if it isn’t broke. I’d like to know if anybody is getting more than 1.6 watts on 20 meters. On Oct 25, 2017, at 9:17 AM, Carlos Gorjao < gorjowski@...> wrote: .... mine on 20 m is giving me on a 50 Ohm load the same as you .... but only after to take out 2 turns on the LPF and add two trimmers?in paralell with the inner LPF?s capacitors C26 and C25 as they after measuring capacitance were not right !! I did already some nice CW QSO?s, like to USA and Hungary ... from my QTH?( Portugal)
73 de Carlos CT7AFN
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Thanks Carlos and Choke, I guess this might be normal for 20 meters. I can’t fix it if it isn’t broke. I’d like to know if anybody is getting more than 1.6 watts on 20 meters.
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On Oct 25, 2017, at 9:17 AM, Carlos Gorjao < gorjowski@...> wrote: .... mine on 20 m is giving me on a 50 Ohm load the same as you .... but only after to take out 2 turns on the LPF and add two trimmers?in paralell with the inner LPF?s capacitors C26 and C25 as they after measuring capacitance were not right !! I did already some nice CW QSO?s, like to USA and Hungary ... from my QTH?( Portugal)
73 de Carlos CT7AFN
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.... mine on 20 m is giving me on a 50 Ohm load the same as you .... but only after to take out 2 turns on the LPF and add two trimmers?in paralell with the inner LPF?s capacitors C26 and C25 as they after measuring capacitance were not right !! I did already some nice CW QSO?s, like to USA and Hungary ... from my QTH?( Portugal)
73 de Carlos CT7AFN
On Wed, Oct 25, 2017 at 4:42 PM, James Anderson <james21170@...> wrote:
Hi Joel.?
40m QCX kit. 12volt supply from a battery to keep the noise down. Achieving just over 3 watts. Far to much power for wspr HiHi.?
But it's nice to have if you really do need it.?
That's into a dummy load though. Real world, probably considerably less..!?
Kind regards. James 2E0MUA.?
On 25 Oct 2017, at 16:24, Joel Caulkins < caulktel@...> wrote:
Hi all,
I just finished and aligned # 628. It's working great, however the power output seems a bit low. I'm getting 1.6 watts at 13.8 V and 1.4 watts at 12.8 V. Does this sound about right? What are others getting out of their QCX's. I realize the power output generally
goes down as the frequency goes up. 1.5 watts is plenty for WSPR and CW contacts. Just curious.
Joel
N6ALT
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Hi Joel.?
40m QCX kit. 12volt supply from a battery to keep the noise down. Achieving just over 3 watts. Far to much power for wspr HiHi.?
But it's nice to have if you really do need it.?
That's into a dummy load though. Real world, probably considerably less..!?
Kind regards. James 2E0MUA.?
On 25 Oct 2017, at 16:24, Joel Caulkins < caulktel@...> wrote:
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Hi all,
I just finished and aligned # 628. It's working great, however the power output seems a bit low. I'm getting 1.6 watts at 13.8 V and 1.4 watts at 12.8 V. Does this sound about right? What are others getting out of their QCX's. I realize the power output generally
goes down as the frequency goes up. 1.5 watts is plenty for WSPR and CW contacts. Just curious.
Joel
N6ALT
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Hi all,
I just finished and aligned # 628. It's working great, however the power output seems a bit low. I'm getting 1.6 watts at 13.8 V and 1.4 watts at 12.8 V. Does this sound about right? What are others getting out of their QCX's. I realize the power output generally goes down as the frequency goes up. 1.5 watts is plenty for WSPR and CW contacts. Just curious.
Joel
N6ALT
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Joel Caulkins/N6ALT
Glenn S