Hi,
I have a number of parts of a mobile (mounted on a 7 ton truck) Warsaw pact
HF military radio. Parts include 1500W HF amplifier (modifiable up to
3.5kW), 3 phase power supplies (HV:3kV,350kV, LV: - 27,-110V,250V) and a
huge 3.5kW tuner.
When I used this HV 3kV psu with my DIY amplifier on 5ye same tube (gu-43b)
I added 16uF smoothing capacitance (13x 220uF 450V electrolyte caps in
series each with a discharge resistor).
This meant the ripple was about 14V at 300mA (this is 3 phase rectified).
With only 10nF it was ~200V or so. It is so, because the PSU has a big
inductor to lower the ripple.
Now I'm restoring the actual military amp and the manual says the smoothing
capacitance is supposed to be 2uF 4kV oil filled capacitor because higher
capacitance will make the arc protection ineffective (it has a relay based
overcurrent protection)
2uF seems awfully small. From the calculations I did (200hz, 200mH
inductance) it seems there will ve 300V of ripple at max current of 1A
(10%!). Isn't that too much and how could the military transmitter work
like this?
Many thanks for your help,
Łukasz, SP4IT
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|