> Thanks for all the ideas, both on and off list. I've got
> some work
> to do when I find some hours. One of the most interesting
> responses was this one from N7KA. The symptoms match mine
> exactly
> on both of the two Titans I own, and I also bought new
> tubes for
> the same reason he did.
...and that suggestion was what? The Titan's I have worked
on use a transistor bias switch. When it fails the power out
and anode current is very low, almost like soft tubes.
I use different transistors to relace them. Most seem to be
the smaller driver transistor and notb the larger bias pass
transistor.
> >>I purchased a used 425 and experienced low output and if
> >>I
>>increased drive output might go up but grid current went
>>way up.
Then you need to advance the loading control. I'd never
build an amp without positive grid overcurrent fault
removal. I've seen first hand how easy it is to cook low
dissipation grids in indirectly heated MOX cathode tubes.
>>Here is what was found to be the problem. The coasx going
>>into
>>and out of the input low pass filter board uses tho9se
>>el-cheapo
>>japanese connectors. found the center conductor of the
>>miniture
>>coax is used a "plug-in" pin into the pcb of he input
>>filter.
>>Guess over time corrosion got the best of it. I soldered
>>both the
>>input and output coax lines (center conductor) to the pc
>>board
>>and mhy problem went away: 1500W out without exceeding
>>the max
>>grid current.
I think it is especially difficult to get a good mental
picture of what is going on.
Are you talking about SWR on the Titan internal meter, or a
grid current issue?
73 Tom
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|