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PAL Electronics 600+ tube amp
- Thread starter Unit 75
- Start date
BJ,
I believe the link below is the same amp in your second link. From the picture in the ad it looks pretty clean. The same seller also lists an AL-80B for $900.00 but does not include a picture.
https://atlanta.craigslist.org/sat/ele/d/mcdonough-ham-radio-estate-sale-huge/7058176312.html
73
David
I believe the link below is the same amp in your second link. From the picture in the ad it looks pretty clean. The same seller also lists an AL-80B for $900.00 but does not include a picture.
https://atlanta.craigslist.org/sat/ele/d/mcdonough-ham-radio-estate-sale-huge/7058176312.html
73
David
Finding 6 tubes that play well together in that final stage could be a nightmare. Don't even expect it to happen if they are not all the same brand and lot number. I would just put this off to the side and wait and see if you may find a set in the future but don't go out and try to buy new ones from different places and piece a set of 6 together. You'll spend top dollar only to burn the strongest ones out very quickly.
The AL-80 was a good suggestion but it will only make about 100 watts or less with a Mark III driving it. You would need another stage in front of it to achieve full output. Also keep in mind it has no RF keying circuit so you will need to add something to fix that or key it manually with a foot pedal.
The AL-80 was a good suggestion but it will only make about 100 watts or less with a Mark III driving it. You would need another stage in front of it to achieve full output. Also keep in mind it has no RF keying circuit so you will need to add something to fix that or key it manually with a foot pedal.
Shadetree Mechanic
Delaware Base Station 808
6 compactron 12 pin tubes.
I know where to get 6kd6 tubes manufacturer and lot matched under $40/each. Im not going to say where here, or now but just know they are available but you either have to know someone or really do your homework. I believe there is about 100 of them in bulk packaging left.
That would be way short on voltage even with a voltage doubler rectifier. It would probably need a tripler and run best at 4 times the voltage of the sweep tube.
There are also a lot of other much less popular sweep tubes still available for peanuts. I retubed a 300A at just $5.95 per tube and purchased all 15 that they had matching at that price. TV manufacturers like Magnavox often used what others didn't. Linear builders avoided these tubes because they typically needed more bias voltage to keep them from over dissipating. Adding a few diodes in a string to cure that bias problem today is far cheaper than buying the original tubes.
If you give up the 6 volt filament, there are even more that can be wired in series to light the filaments from line voltage. If you do that in a 6 tube final stage, you must treat the filament as a directly heated one and add RF chokes inline with it. That keeps the filament at the same RF voltage as the cathode and prevents them from shorting together under the higher drive level.
Incidentally, if you are ever building an 8877 amplifier you will want to use RF chokes in its filament lines too. Even though it is not required on that tube, it sure does make them more reliable when driven hard.
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