Re: Drake L-7
The original? C41 cap (47 pf) is failure prone.? ?Replace it with a 50 pf TX doorknob cap.? ?The original cap? was made from pc board. C42? ( 307 pf)? is used to pad the TUNE cap on 160m
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Jim VE7RF
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#41002
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Re: Commander HF-2500 Plate Choke
The 3 x section choke,? currently sold by ameritron,? is now screwed up.? Ameritron ran outa 28 ga wire...and started using 27 ga wire.? ?The pair of gaps is way less.? Steve at RF parts got a
By
Jim VE7RF
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#41001
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Re: Drake L-7
Hello Thank you for this communication. Even if it does not answer my question, this document is very interesting, both at the technological and implementation level. I reformulate my initial
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Fran?ois
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#41000
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Re: Commander HF-2500 Plate Choke
Dear Riki, Tom, W8JI, <%0dW8JI%0d#W8JIhttps://www.w8ji.com> W8JI<%0dW8JI%0d#W8JIhttps://www.w8ji.com> [cid:image001.png@...]<%0dW8JI%0d#W8JIhttps://www.w8ji.com>
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HaL Mandel
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#40999
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Re: Drake L-7
Dear Francois, Attached, please find a great book about tubed amplifiers. '73, Hal Mandel W4HBM
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HaL Mandel
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#40998
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Re: Drake L-7
I am still studying a way to cook my 3-500Z which have not been hot for at least 15 years. The idea is to cook at high current with a low anode voltage, without HF. The maximum rating of the cathode
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Fran?ois
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#40997
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Re: Drake L-7
Yes, a ¡°single diode path¡± would have made it clearer. Thanks for the clarification. What I understood is that these diodes are used to protect the galvanometers in the event of an arc in the PA
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Fran?ois
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#40996
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Re: Commander HF-2500 Plate Choke
Hi Riki I own a 1990 HF-2500 which I got from the estate of a local ham many years ago. I had a question about it on this forum last week but through perseverance and much hair pulling, I managed to
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Alek Petkovic
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#40995
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Commander HF-2500 Plate Choke
Somebody who previously owned my Commander HF-2500 replaced the carbon resistors in the plate parasitic chokes with a different type of resistor.? This worked fine on low frequencies 160M, 80M, and
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Riki, K7NJ
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#40994
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Re: Drake L-7
Yes, a ¡°single diode path¡± would have made it clearer. Here more then 0.7V are clamped, depends on the meter or meter shunt for grid current. Zener diode can be used as well or a germanium diode
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Peter Voelpel
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#40993
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Re: Drake L-7
http://radiojim.exofire.net/pages/Glitch%20diodes.html -- F1AMM Fran?ois De la part de Peter Voelpel Envoy¨¦ : mercredi 29 janvier 2025 18:37
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Fran?ois
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#40992
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Re: Drake L-7
That clamp diode is typically a single diode. 73 Peter, DJ7WW -----Original-Nachricht----- Betreff: Re: [ham-amplifiers] Drake L-7 Datum: 2025-01-29T13:33:50+0100 Von: "Jim VE7RF via groups.io"
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Peter Voelpel
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#40991
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Re: Drake L-7
Does the following diagram correspond to your proposal? What is the green diode used for? -- F1AMM Fran?ois De la part de Jim VE7RF via groups.io Envoy¨¦ : mercredi 29 janvier 2025 13:34
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Fran?ois
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#40990
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Re: Drake L-7
A diode clamp is simply? a pair of REVERSE connected diodes, like 1N5408 / 6A10 / PM-600? type diodes.? ?They are wired between the B-? and the chassis.? Then the B- can never wander more than
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Jim VE7RF
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#40989
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Re: Drake L-7
https://www.w8ji.com/vacuum_tubes_and_vaccum_tube_failures.htm Anode systems should have series-resistance to limit peak current in the event of a tube arc or failure. That series resistance should
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Fran?ois
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#40988
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Re: Drake L-7
No problem Hal! 73, Evert <https://www.qrz.com/db/PA2KW> PA2KW / <https://www.qrz.com/db/5T2KW> 5T2KW / <https://www.qrz.com/db/W8S> W8S Sent: Tuesday, 28 January 2025 18:14 To:
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Evert Bakker
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#40987
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Re: Drake L-7
Gentlemen, My apology. I was thinking you were talking about Grid Bypass circuits of caps and chokes instead of Anode Bypass. As a compliment, the W8JI program of analyzing and preparing Anode Chokes
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HaL Mandel
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#40986
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Re: Drake L-7
Dear Everett et al, There are those that believe a Pi-Wound, or even a Solenoid-Wound inductor is the Saving Grace of QRO amplifiers. And there are those who think that monsters are really hiding in
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HaL Mandel
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#40985
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Re: Drake L-7
I was told that the original RF-choke could cause oscillation. 73, Evert PA2KW <https://www.qrz.com/db/PA2KW> / 5T2KW <https://www.qrz.com/db/5T2KW> / <https://www.qrz.com/db/W8S> W8S Sent: Tuesday,
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Evert Bakker
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#40984
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Re: Drake L-7
Thanks Dave. Always ¡°good¡± to hear the issues! In the L7 the RFC3 was ok (no issues in 15 years) 73, Evert PA2KW <https://www.qrz.com/db/PA2KW> / 5T2KW <https://www.qrz.com/db/5T2KW> /
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Evert Bakker
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#40983
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