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50w QCX amp with grounded ptt (elecraft k2)
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Hey all,
I suspect this has been asked and answered, but I cannot find it. I have an elecraft k2 with an amp keyer jack that is an open drain output and is pulled to ground during transmit. I would like to add the QCX 50w amp. I understand what it required electrically, but I'm curious what the most practical way to connect the two would be. Is there a way to tap 5v off of the amp, so the keyer ckt can be passive? I'd like to maintain QSK capabilities. Thanks in advance, Casey KV3T |
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W8DIZ “Diz,” from Kits and Parts SK, R.I.P had a really cool way to do this-
Use a 78L05 regulator tied to the amp B+ in (~22V in the QRP Labs case) Tie the output of the regulator to amplifier PTT (5V active high) Connect the gnd pin of the regulator to the PTT circuit of the rig.? So when the PTT provides a ground to the regulator, it switches on, and 5V is used to activate the 50W amp. I used this idea to build a 50W amp and one of Diz’s 5Watter rigs together in a case. At 12V in, it makes about 25W, and runs cool. Larry KB3CUF? |
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Playing around with this idea a bit, I think what I'm going to do is get a voltage booster, and put it in a small separate device.? On that device I'll do an RCA PTT jack from the radio, put the 78L05 regulator in that case tapped off the 12v input, and then the +5v output to the amp.? That way the amp can remain 'stock', and I have another small companion device that will stay with it to boost the voltage to 22v, and provide the +5vdc keying signal.
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Sure, that would work . ? You will need about 5A at 20V to make full output.? I used a Meanwell 110V to 24, modified it to 20V out, and put the 78l05 in a glob of tape inside the amp. Hans’ document says 20V but I have heard of slightly higher. I stuck with 20V or less.? Larry KB3CUF? On Sun, Mar 31, 2024 at 1:15?PM casey via <casey=[email protected]> wrote: Playing around with this idea a bit, I think what I'm going to do is get a voltage booster, and put it in a small separate device.? On that device I'll do an RCA PTT jack from the radio, put the 78L05 regulator in that case tapped off the 12v input, and then the +5v output to the amp.? That way the amp can remain 'stock', and I have another small companion device that will stay with it to boost the voltage to 22v, and provide the +5vdc keying signal. |
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Is this true, that Dieter Genschow W8DIZ is 'sk' ??
I am sorry to hear this, ... when does he passed away?? A few years ago, i purcased two of his 'One-Watters' radios, a 30m and a 40m version. Later he came up with the 5Watter-typ. What a lovley radio, this 'kit' is! With 1,6W, at 03:45h UTC , I managed to? contact W1AW/KP4, during a ham-fest in. Puierto Rico. This special QSO was more for me, than 10 QSO with VK, on 20m and 500W, with a PA! It was all 'home-brew' and 'handmade' by myself, ... only expection was my Schurr-Keyer)? Beautifull CW-TRX, the 'One-Watter' and also the '5-Watter' !? 73 de Markus - db9pz (JN39fq - 3miles/5km east of LX) |
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Diz had been ill for a while.
As far as I know his family and friends are helping keep KITSANDPARTS.com alive and hve been doing this for a while. This was on QRPARCI. -------- Forwarded Message --------
It is with a heavy heart that I bring the news that Dieter "Diz" Gentzow, W8DIZ, lost his battle with his illness yesterday, March 3rd, 2024. He passed away at home with his family nearby. Diz was a good friend and a great Ham, and I know we all will miss him. Please take a moment and think about him and remember any good times you got to share with him. Diz's wife Nancy asked me to relay this news to you, and to thank you all for your thoughts and prayers over the last two years. Rest easy my friend. Mike M. KU4QO -- Allison ------------------ Post online only,? direct email will go to a bit bucket. |
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73 Hans G0UPL On Mon, Apr 1, 2024 at 5:44?PM ajparent1/kb1gmx <kb1gmx@...> wrote: Diz had been ill for a while. |
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Hi Larry, could you provide more details about this circuit? I tried it but it didn't work.
Tie the output of the regulator to amplifier PTT (5V active high)I understand the on/key-down state here. But what about the off/key-up state? IIUC, when the rig is in off/key-up sate, the ground pin of 78L05 is floating and I believe in that case, the output and the ground pin will both see a voltage at about 1V less than the input voltage. In the attached picture below, pin1 is Vout, pin 2 in Gnd, and pin 3 is Vin. The inner pin of the DC ?connector is at about 11.6V. With pin 2 floating, I measured 10.6V at both pin 1 and pin2 which means if pin1 is connected to the 50W amp's active high PTT, the amp will always be in the TX state. Did I missing something? 73 de Zhenxing N6HAN |
Markus
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