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Re: Drake L-7
开云体育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 is topnotch in the Land. ? Hal Mandel W4HBM |
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Re: Drake L-7
开云体育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 their granddaughters’ closets, and that hidden, destructive parasitic oscillations reside, ready to lash out on unsuspecting operator equipment. ? Both camps are correct. RF energy behaves more like sub-atomic particles riding waves of phase change DC energy, excited somehow in more direction than only one, and possible at the very same time. ? Modeling software is only a test to see if something’s kosher or not at a readily recognizable set of params, so what, and why did my amplifier, after hours and hours of QSY everywhere and outside antenna follies, decide to go, “BINK!” and leave me with a $5,000 set of ceramojunk? “ Parasitic Oscillations,” the well-remembered AG6K would say, while his close friend(s) would say, “Hogwash!,” and both were right? ? (I still have small rolls of Nichrome 30 and Nichrome 60 if anyone needs any.) ? The circuit recommendation to avoid hi-impedance pathways is achievable by a method to bolster the ampacity. Using something with a wide bandwidth helps. ? Most Pi-W’s use microscopic wire.? Some Grid Anomalies may induce a bolt of juice in them tubes, there, of Just How Many Amperes Wre You Thinkin’?? Bazillions? You may be right, but how long was that for? ? In that infinitesimal slot your Pi-W’s windings are going to heat up, maybe in more than one place, and what’s next? Current Down, Voltage Up: Goombye Grid. ? It might as well be mentioned a nice fat slug of copper wire in between every G1 tube socket and chassis ground for as short a distance as possible makes a reliable addition to the design of all. ? Tetrode rigs, especially Grid-Driven behemoths, need great bypassing on their tube sockets. Now thems are serious monsters under the bed. ? Hal Mandel W4HBM |
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Re: Drake L-7
开云体育Thanks Dave. Always “good” to hear the issues! In the L7 the RFC3 was ok (no issues in 15 years) ? 73, Evert ? / / ? From: [email protected] <[email protected]> On Behalf Of Dave w6de
Sent: Tuesday, 28 January 2025 01:06 To: [email protected] Subject: Re: [ham-amplifiers] 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 differ.? ? 73, Dave, w6de ? ? ? From: [email protected] <[email protected]> On Behalf Of Evert Bakker via groups.io ? I found the RF-choke I used : ?
? ? 73, Evert ? / / ? From: [email protected] <[email protected]> On Behalf Of Fran?ois via groups.io ? Hello, ? > Do you have the service manual of this amp? ** No, I don't have the service manual for this amp. If you could share it with me, it would be appreciated. ? > I remember the green capacitor (B) but not (A). ** Your capacitor 'A' went with your old RF choke. ? ? A= 47 pF B= 307 pF ? Thanks for the images of your modifications; they can be very useful to me -- F1AMM Fran?ois De la part de Evert Bakker |
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Re: Drake L-7
开云体育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. On 28/01/2025 8:06 am, Dave w6de wrote:
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Re: Drake L-7
开云体育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 differ.? ? 73, Dave, w6de ? ? ? From: [email protected]
<[email protected]> On Behalf Of Evert Bakker via groups.io
Sent: 27 January, 2025 20:32 To: [email protected] Subject: Re: [ham-amplifiers] Drake L-7 ? I found the RF-choke I used : ?
? ? 73, Evert ? / / ? From:
[email protected] <[email protected]>
On Behalf Of Fran?ois via groups.io ? Hello, ? > Do you have the service manual of this amp? ** No, I don't have the service manual for this amp. If you could share it with me, it would be appreciated. ? > I remember the green capacitor (B) but not (A). ** Your capacitor 'A' went with your old RF choke. ? ? A= 47 pF B= 307 pF ? Thanks for the images of your modifications; they can be very useful to me -- F1AMM Fran?ois De la part de
Evert Bakker |
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Re: Drake L-7
开云体育I found the RF-choke I used : ?
? ? 73, Evert ? / / ? From: [email protected] <[email protected]> On Behalf Of Fran?ois via groups.io
Sent: Monday, 27 January 2025 07:02 To: [email protected] Subject: Re: [ham-amplifiers] Drake L-7 ? Hello, ? > Do you have the service manual of this amp? ** No, I don't have the service manual for this amp. If you could share it with me, it would be appreciated. ? > I remember the green capacitor (B) but not (A). ** Your capacitor 'A' went with your old RF choke. ? ? A= 47 pF B= 307 pF ? Thanks for the images of your modifications; they can be very useful to me -- F1AMM Fran?ois De la part de Evert Bakker |
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Re: Drake L-7
开云体育Francois, ? > I remember the green capacitor (B) but not (A). ** Your capacitor 'A' went with your old RF choke. ? Yes, you are correct. ? ? 73, Evert ? / / ? From: [email protected] <[email protected]> On Behalf Of Fran?ois via groups.io
Sent: Monday, 27 January 2025 07:02 To: [email protected] Subject: Re: [ham-amplifiers] Drake L-7 ? Hello, ? > Do you have the service manual of this amp? ** No, I don't have the service manual for this amp. If you could share it with me, it would be appreciated. ? > I remember the green capacitor (B) but not (A). ** Your capacitor 'A' went with your old RF choke. ? ? A= 47 pF B= 307 pF ? Thanks for the images of your modifications; they can be very useful to me -- F1AMM Fran?ois De la part de Evert Bakker |
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Re: Drake L-7
开云体育Hello, ? > Do you have the service manual of this amp? ** No, I don't have the service manual for this amp. If you could share it with me, it would be appreciated. ? > I remember the green capacitor (B) but not (A). ** Your capacitor 'A' went with your old RF choke. ? ? A= 47 pF B= 307 pF ? Thanks for the images of your modifications; they can be very useful to me -- F1AMM Fran?ois De la part de Evert Bakker |
HaL Mandel