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Another Ameritron problem.
- Thread starter AudioShockwav
- Start date
Ok I see here on the Youtube video description he adds this:
The second issue is mainly when PP100 transistors are used in place of 2SC2879 transistors. The amplifier has a large current spike. The PP100's have a lower base bias threshold, typically I measure around .51 volts or so, and high dc current gain at idle. The bias circuit has a very brief (a few milliseconds) spike of around .75 volts before it settles to operating bias levels. The PP100's also have a good bit more VHF gain. This causes the amplifier to momentarily oscillate upon relay closure.
The second issue is mainly when PP100 transistors are used in place of 2SC2879 transistors. The amplifier has a large current spike. The PP100's have a lower base bias threshold, typically I measure around .51 volts or so, and high dc current gain at idle. The bias circuit has a very brief (a few milliseconds) spike of around .75 volts before it settles to operating bias levels. The PP100's also have a good bit more VHF gain. This causes the amplifier to momentarily oscillate upon relay closure.
I never knew Ameritron used "PP100" outputs until now.
But I do know Ameritron is owned by "MFJ" now and that pretty much explains it all.
Take their most expensive amps... a 1 year warranty.. So they are not expecting, they are hoping your 5 thousand dollar linear lasts a year.
I get a 6 month warranty on all the tubes I use from my distributor in our guitar amps we manufacture.
I bought a new 300 watt mfj matchbox at the Dayton fest a few years ago. The metering never worked. Turned it in 3 days later, 8 month later I got it back. Exact unit, I etched it. And guess what. Just as phucked as when I got it. Still have it. And on top of it. The dummy load is 57 ohms... that's 14%!
But I do know Ameritron is owned by "MFJ" now and that pretty much explains it all.
Take their most expensive amps... a 1 year warranty.. So they are not expecting, they are hoping your 5 thousand dollar linear lasts a year.
I get a 6 month warranty on all the tubes I use from my distributor in our guitar amps we manufacture.
I bought a new 300 watt mfj matchbox at the Dayton fest a few years ago. The metering never worked. Turned it in 3 days later, 8 month later I got it back. Exact unit, I etched it. And guess what. Just as phucked as when I got it. Still have it. And on top of it. The dummy load is 57 ohms... that's 14%!
I too have an older one with 2879's and use it with the ALS-500RC remote and it works fine. I tried it with the ARI-500 remote auto-band switch and it seems RF or something else occasionally will trip the amp into fault to where it was too aggravating to bother with it.
Seems like putting a simple fuse in line on the internal remote wires would be a good idea.
Seems like putting a simple fuse in line on the internal remote wires would be a good idea.
It continues.
Brand new amp with a solder blob under the flange when it was bolted down.
Fail.
73
Jeff
Brand new amp with a solder blob under the flange when it was bolted down.
Fail.
73
Jeff