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
By
Fran?ois
·
#40997
·
|
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
By
Fran?ois
·
#40996
·
|
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
By
Alek Petkovic
·
#40995
·
|
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
By
Riki, K7NJ
·
#40994
·
|
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
By
Peter Voelpel
·
#40993
·
|
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
By
Fran?ois
·
#40992
·
|
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"
By
Peter Voelpel
·
#40991
·
|
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
By
Fran?ois
·
#40990
·
|
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
By
Jim VE7RF
·
#40989
·
|
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
By
Fran?ois
·
#40988
·
|
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:
By
Evert Bakker
·
#40987
·
|
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
By
HaL Mandel
·
#40986
·
|
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
By
HaL Mandel
·
#40985
·
|
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,
By
Evert Bakker
·
#40984
·
|
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> /
By
Evert Bakker
·
#40983
·
|
Re: Drake L-7
I've just bought 4 from W8JI at CTR Engineering. Installed one in my AL-1500 and one in my home brew 2 x 3-500Z 160 to 10 amp. No problems on any band with those chokes. 73, Alek VK6APK.
By
Alek Petkovic
·
#40982
·
|
Re: Drake L-7
I found the RF-choke I used : https://www.rfparts.com/rfc3.html Thanks 225 ?H; that's a big value indeed. I thought you wound it yourself on the original mandrel. Why did you have to change this
By
Fran?ois
·
#40981
·
|
Re: Drake L-7
From my own experience in blowing up two of those, is that RFC3 RF-choke purchased from RF-Parts is resonant on 30 meters when used in a 3-tube (8874) Alpha 76A amplifier. Use in other amplifiers may
By
Dave w6de
·
#40980
·
|
Re: Drake L-7
I found the RF-choke I used : https://www.rfparts.com/rfc3.html 73, Evert <https://www.qrz.com/db/PA2KW> PA2KW / <https://www.qrz.com/db/5T2KW> 5T2KW / W8S <https://www.qrz.com/db/W8S> Sent: Monday,
By
Evert Bakker
·
#40979
·
|
Re: Drake L-7
Francois, ** Your capacitor 'A' went with your old RF choke. Yes, you are correct. 73, Evert <https://www.qrz.com/db/PA2KW> PA2KW / <https://www.qrz.com/db/5T2KW> 5T2KW / W8S
By
Evert Bakker
·
#40978
·
|