Inherited homebrew tube amp....help!
I inherited an amp from my grandfather that he built that uses 4 6KD6 RCA tubes. I have had it for about six years in storage and I do not know how it was stored before I obtained it. With that said, I'm trying to figure out if it will work, how much power I should drive it with, and how much I can get out of it. I am completely new to anything doing with tubes, but I would like to learn about them. I did some research trying to find information about other home-brewers that possibly made a similar amp because he did a lot of brewing from handbooks. I was able to track down a post on a forum that sounded similar to this one that was published in the 1969 ARRL handbook on page 192 I think....I couldn't find that particular publication online...for free at least.
Can anyone assist me with my previous questions as well as a few others? The other questions I have are what is the process to 'tune' this amp in order to test it? Is there a schematic somewhere out there that someone might have? I want to find as much information on this as possible. I have messed with it a little and it turns on and the tubes glow. I have checked it with an swr meter while in standby and it's not flat, but it's within acceptable operating range.
Any help is welcome! Thanks
I attached a couple of pictures of it to show it. It's kinda dusty inside....
That is so cool!
I suggest you find some local experienced help before turning it on or testing for all the standard safety reasons.
Reverse engineer the rig and create schematic. It is homebrew. You can't do much without knowing the circuit. It is a good learning experience.
Do some research about amps by reading some of the information available including similar period Handbook amps.
There are fellas like WB2WIK/6 on this site who are amp homebrewers that can likely guide you once you can identify the circuit.
You are so very lucky to have a homebrew rig of your grandfathers.
Last edited by K5UOS; 01-06-2010 at 03:51 PM.
The phrase google is loking for is "sweep tube amplifier", or "sweep tube linear"
Now my mistakes travel at the speed of light!
The 1968 ARRL handbook has a construction article on a four tube 800 watt sweep tube linear that might be a good place to start. Typically they discuss startup, tune, and troubleshooting porcedures as part of the write up.
If I can find mine (no idea where it is right now) I can send you some xeroxes.
Thanks LZ, that would be great! I wish there was an easy way to get hold of old issues online or something....
- The Constrictor
Try arrl.org online. You may have to join to find what you want. I'd suggest that every ham join. It's not perfect but it's all we have to keep the "Wolves" from taking our frequencies away.
Hey Blake (WD5BOA),
Go Red Raiders! I'm a 1980 graduate of their Electrical Engineering school.
Maybe this would help:
If you are an ARRL member, you can go to this webpage: http://www.arrl.org/tis/info/amplifir.html and look about halfway down the page for the article: A Sweep-Tube Linear Amplifier (four 6KD6) (1,201,283 bytes, PDF file) ARRL Handbook 1972, pp. 176-178
Last edited by N5AL; 01-07-2010 at 03:47 AM.
I finally got around to taking off the bottom cover to look around a bit so I took a few pictures to post here for all to see. I know I like seeing different projects so that is why I added these. As is visible in one of the photos...I see at least one issue....
- The Constrictor
Wow.... what a mess.
It would be worth adding a few terminal strips down there and cleaning up some of that rats nest. The bridge? (the one with the busted diode) just floating in air like that and kinda hanging off the end of the filter caps, even looks a tad dangerous.
The first question is did it ever work? and if so, how well.