Hi all
I have been building a 70cm GS35B amplifier and it's not working
Here are pictures of the amplifier
http://www.tf3cy.is/70cm-gs35b-amplifier
So - I have done and noticed:
* turned on the amplifier with HV
*When I started the amp for the first time the anode trip on the GM3SEK
triggered.
(video: https://www.youtube.com/watch?v=cU4wXqeDOjo ) <- first time I turned
him on with HV
Perhaps I did a mistake there of clearing the alarm - bit anxious.
* When keyed - it draws around 200mA current on Plate.
* When keyed and and driven (10-20W) no changes on the plate/grid meter (grid
meter never moves)
* input tuning works - I can tune to low SWR
* Grid meter never moves (all calibrated using methods in the Triode manual by
GM3SEK)
* 12V AC (bit low) filament measured on the feedthrough capacitors into the
input compartment.
* When I was driving the amp - the PSU tripped a 16A breaker few times - but
after letting the amp sit with
Filament + HV for some time - (1hr) it stopped doing that - this must have been
a arc inside the tube - I really cant find what would have caused this.
When writing this I notice that I don't have any capacitor on the filament
transformer. - is that perhaps key?
I notice in my design there is no RFC on the output - I would assume that is a
major safety issue.
Or could this be a faulty tube ? It went through some knocking when getting the
cooler off (it was supposed to go into a 2m amp)
And a bonus question
* if you look closely at the picture of the power supply - I put a 4 way
ceramic switch on the AC output of the Peter Dahl transformer so I can switch
from approx. 2kv-4kv
* CAN I move this switch with HV on ? (have not tried it!)
73, Benni TF3CY
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|