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Re: Grid bias 3-500Z
Hello Now that both of my 3-500Zs have been de-gassed, I have a new question. ¡¤ In the L7 (Drake) the bias is at 0 volts ¡¤ In the Kenwood TL-522 it is -7.5 V as shown in the following diagram We
By Fran?ois · #41038 ·
Re: Drake L-7
1-2 hrs max...per tube. Alright. Then I'll do the second 3-500Z valve. Then I'll do the full voltage tests with the Drake's HT transformer -- F1AMM Fran?ois De la part de Jim VE7RF via groups.io
By Fran?ois · #41037 ·
Re: Drake L-7
1-2 hrs max...per tube.
By Jim VE7RF · #41036 ·
Re: Drake L-7
Hello Cooking the tubes. It was necessary to modify the tube polarization system. As shown previously, the HT power supply is floating relative to ground. This trick allows the cathode voltage (the
By Fran?ois · #41035 ·
Re: Ameritron AL-1500 Relay
I had a bad relay on my Al-811H and went this route. There¡¯s a write up on DX World here: https://www.worldwidedx.com/threads/ameritron-al811-relay-headache-solved-my-way.265840/ I bought special
By Elijah · #41034 ·
Re: Ameritron AL-1500 Relay
The AL1500 relay is a typical 3pdt 12v relay. ?There is nothing magical about it. ?There are many relays that can be subsidized for it if the original cannot be found. ?With Ameritron going out of
By Louis Parascondola · #41033 ·
Re: Ameritron AL-1500 Relay
Try w8JI, CTR Engineering, he may have one. 73? Andy? K9ATX -- "Where the Old Soo crossed the
By DupyRail · #41032 ·
Ameritron AL-1500 Relay
The output relay in my Ameritron AL-1500 needs to be changed. I checked with MFJ since they are still selling some Ameritron replacement parts, but no luck.? From the user manual, this is "RLY1" and
By Riki, K7NJ · #41031 ·
SVHFS Conference 2025, Call for Papers & Presentations
Here's an update on the SVHFS 2025 Conference; Deadline for papers has been extended to March 17 Registration is open; details are in the attached file. Thanks, Robin Midgett K4IDC
By Robin Midgett · #41030 ·
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 600¦¸ input. 5K/10K¦¸ P-P to 600¦¸ transformers are usually available. Turn them around and drive the grids of your
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 ·