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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
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
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
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
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
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 ·
Dentron DTR-2000L info
Hi All, I have a DTR-2000L that I'm trying to bring back to life.? It's the same one that I asked about last year.? What I'd like is IF someone that has one of these amps, that's working, would you
By Kim Herron · #40977 ·
Re: Commander HF-2500
Hi Alek, I’ve seen some of the older units and worked on them. ?The real old ones had no grid trip circuit and so I made up a circuit board ?with a trip circuit and implement it on the old units.
By Louis Parascondola · #40976 ·
Re: Drake L-7
Hello, ** No, I don't have the service manual for this amp. If you could share it with me, it would be appreciated. ** Your capacitor 'A' went with your old RF choke. A= 47 pF B= 307
By Fran?ois · #40975 ·
Re: Drake L-7
Fran?ois, here are the exact capacitors I used to replace C41 and C42 in my L7: https://www.rfparts.com/catalogsearch/result/?q=580050-7P https://www.rfparts.com/catalogsearch/result/?q=580300-7
By Fran?ois · #40974 ·
Re: Drake L-7
Fran?ois, here are the exact capacitors I used to replace C41 and C42 in my L7: https://www.rfparts.com/catalogsearch/result/?q=580050-7P https://www.rfparts.com/catalogsearch/result/?q=580300-7 I
By Paul K6PO · #40973 ·
Commander HF-2500
This is a real long shot. I have an old Commander HF-2500 which I love very much. It is Serial Number 186 and it conforms with the printed manual and schematic of June 1990. However, there is no
By Alek Petkovic · #40972 ·
Re: Drake L-7
Hi Francois, I did not document my changes and sold the amp a few years ago. I remember the green capacitor (B) but not (A). That could easily be a memory leakage on my side but I couldn’t
By Evert Bakker · #40971 ·
Re: Drake L-7
Hello I am weak in technology (I am 75 years old). It seems to me that you are pointing out the two curious plate capacitors A = C41 (47 pF) and B = C42 (307 pF). Could you give me,
By Fran?ois · #40970 ·
Re: Drake L-7
The reason is in this message /g/ham-amplifiers/message/40898 -- F1AMM Fran?ois De la part de Evert Bakker via groups.io Envoyé : samedi 25 janvier 2025 19:38
By Fran?ois · #40969 ·