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Re: Drake L-7
WRX, with 200w drive, how much grid and plate current was it running? Bob W4JFA [email protected]> wrote:
By Bob · #41029 ·
Re: Drake L-7
Which models had 4kv on the plate? A Triode is only going to give 10 to 12 DB of gain. Man, I have worked on and rebuilt pretty much all of these amps and even the later 3KA with its HD supply won't
By W7WRX · #41028 ·
Re: Drake L-7
The Tokyo High power HL2K? with 3-500s was also such a amp. It had proper cooling(fully pressurised) On 240 VAC it could easily hit 2KW pep even though it was rated for 1.2KW PEP. Much like the TL922
By tardivat@... · #41027 ·
Re: Drake L-7
It’s a well known fact that the Ameritron AL80b can obtain 1kw output ?pep?with a single 3-500. They only run 3000 volts anode voltage. ?The old Henry amps made prior to the power rule change
By Louis Parascondola · #41026 ·
Re: Drake L-7
Which henry amps were rated at 2kw out Jim? C ________________________________ Sent: Friday, February 14, 2025 3:29 AM To: [email protected] <[email protected]> Subject: Re:
By W7WRX · #41025 ·
Re: Drake L-7
Some versions of the older Henry amps were rated for 2 kw pep out on ssb.? But they also had improved cooling and also a bigger B+ supply. To getter older tubes, on the drake L7,? you can use the
By Jim VE7RF · #41024 ·
Re: Dilemma
Hi Mike I'll try that transformer thing when I get to that point.. thanks don
By kc1at · #41023 ·
Re: Dilemma
I would be interested to know how you interface the TOA amp to the modulator tubes in my case using a pair TZ40s? 73 Mike VK2AMF
By mfle2001 · #41022 ·
Re: Dilemma
Don, I’m not sure if you know this, but you can use the 70.7V output to drive a 600Ω input. 5K/10KΩ P-P to 600Ω transformers are usually available. Turn them around and drive the grids
By Mike Sawyer · #41021 ·
Re: Dilemma
Thats what I'm leaning towards now. Scrap the input with all those 12AU7s and do something else. Reverse engineering that circuit seems fruitless . Not sure it even worked when built. Took a look at
By kc1at · #41020 ·
Re: Dilemma
I would rip all the front-end tubes out and drive it with a 10W TOA amplifier. You can get these cheap on ebay and other websites. $20 to $30 bucks. They have 4/8 and a 70v output with balanced and
By W7WRX · #41019 ·
Re: Dilemma
WOW.... thanks so much for the input. Let me try to answer some of the questions Oops....its not a 350 watt modulator its a 300 watts. The thing is a monster. Has 4 - 12au7s into a pair of 6146's
By kc1at · #41018 ·
Re: Dilemma
Sounds good. I have a HB rig with two 4-400s modulated by 304TLs. It runs 10 to 160. I have had it on 10 and 20 recently. Through a 4 elment mosley. Over 300 contacts on 10-meter AM. If you want to
By W7WRX · #41017 ·
Re: Dilemma
Well, not much on the air these days, mostly on 160M, 75M, and sometimes on 40M in the so called "AM windows" Spending much more time on other infinite money sinks like olde cars and astronomy.
By Chuck Neal · #41016 ·
Re: Dilemma
Addendum: I’ve built many rigs using Eimac tubes from the 4-65A to 4-1000A’s to ceramics like the 4CX1500A (Not to be confused with the 4cx1500B). One rig was a pair of 3CX1200A7’s
By Chuck Neal · #41015 ·
Re: AL-82 Date of Manufacture
Matt, Thanks for the reply. 73, Garry
By Garry - K4OR · #41014 ·
Re: Dilemma
Dear Don, (et al, of course), You are going through a time very similar to my own experiences. I was hot and heavy on HB QRO tube-type amps, and built them one after another. It was necessary to put
By HaL Mandel · #41013 ·
Re: Dilemma
Hey Chuck. Have not had a QSO is a long time. Where are you hanging out these days on AM? W7WRX ________________________________ Sent: Tuesday, February 4, 2025 9:38 AM To: [email protected]
By W7WRX · #41012 ·
Re: Dilemma
Grid drive one 4-400 with bias and screen voltage. Then you can run Class C for plate modulation and bias it for AB1 or AB2 operation for SSB amplifier mode. A Johnson ranger or similar power
By Chuck Neal · #41011 ·
Re: Dilemma
Are you planning on using the modulator with this amplifier? If so a Single 4-400 will do 550 to 600 carrier and would be a good match for that 350-watt modulator for AM. It's a simple circuit.
By W7WRX · #41010 ·