Put RF to the 2 3cx800's inside the mla2500 box today.
Lots of work before it's ready to go into the shack but the
observations:
1. condition of 3cx800's is unknown (bought used via swap usenet).
2. condition of amp in question (bought used, one of privious owners
is a well known hard-core RTTY type).
3. Fired up filaments first on outboard filament transformer.
4. Fan & HV fired up fine. 1500VDC in CW position / 2200 VDC in SSB
position.
5. Driving rig was TS180 (this is a 200 watt rig).
6. Tested TS180 at 100 into dummy load. Watt meter on 2500 read
1000 watts. Strange noise coming from area of the meter board.
7. Reduced output from ts180. Put amp on line and keyed up.
8. Working.
9. Tune output. output > input. good sign.
10. Slowly increase drive. At 1000 watts out (on good wattmeter) the
15 amp fuse in 2500 blows. (did same thing with 8875's, no surprize).
11. Nice warm air is blowing out top of the tubes..
12. Remove HV & filament. Let fan run awhile. Cools down pretty quick.
Amp was wired for 120VAC. Well the 2500 transformer is proably around
a 800 watt rating on the HV winding CCS? so this will never be a
"amp with handles". I still suspect one of the amp's original parts is
not right. Helpful thoughts??
--
73 Robert W5AJ w5robert@blkbox.com
WB5CRG, VK5CRG, WB5CRG/VP2M & VP2E & WN5CRG !
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