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
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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:
By
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
By
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
By
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
By
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>
By
Evert Bakker
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#40983
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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
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#40982
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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
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#40981
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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
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#40980
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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
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#40979
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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
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#40978
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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
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#40977
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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
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#40976
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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
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#40975
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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
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#40974
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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
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#40973
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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
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#40972
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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
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#40971
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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
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#40970
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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
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#40969
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