View Single Post
Old 8th Nov 2018, 1:34 pm   #1
G3PIJpeter
Hexode
 
Join Date: Nov 2011
Location: Chippenham, Wiltshire, UK.
Posts: 319
Default FT200 mains power supply

I have recently revived a car boot sale Sommerkamp FT250, which is the same as the Yaesu FT200. Considering the heterodyne oscillator crystals that I have replaced, the previous owner seems to have been a 27 MHz CB devotee and MARS (6.5-7.0 MHz) contributor. One of the 'sweep toob' 6JS6s also had a shattered envelope and a large hole burned through its anode. Substituting 6146Ws with 600 V on the anodes and 160 V on the screens, I have an output of 50 watts carrier / 70 watts peak SSB on 80 and 40 metres.

The accompanying FP200 mains PSU is advertised as putting out 600, 150, 300 and -100 volts. All of these are correct, except the 300 V line which measures at 370 V (on-load). Various sources on the internet speak of this HT line being either 300 V or 350 V. Nothing runs super-hot, even the class A audio output stage, which takes the full 370 V on its anode.

My questions are:
1. What should the HT line voltage be - 300 V or 350 V?
2. Is my HT running at 370 V likely to inflict lasting damage, despite the apparent absence of over-heating?
3. Just what should the screen voltage of AB1 6146s be? (Data books say 180 but many designs use 250 V or more).

Many thanks

- Peter G3PIJ
G3PIJpeter is offline