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eHam Forums => Amplifiers => Topic started by: ZL1BBW on February 20, 2018, 11:37:44 AM



Title: L4B got easier to drive as contest went on.
Post by: ZL1BBW on February 20, 2018, 11:37:44 AM
First time I have given the Amp a reasonable workout, at the start of the ARRL it was quite hard to drive to a KW, but as time went on over the 8 or so hours I operated it got easier and easier, in the end I was able to get about 900 watts out with about 50% of the power in from the start.

Presume this is as the tubes got warmed up abit? did not see any red in them but the light was really quite bright here.

Thoughts?  Thanks  Gavin ZL1BBW


Title: RE: L4B got easier to drive as contest went on.
Post by: VR2AX on February 22, 2018, 04:33:08 AM
If the normal checks are what you expect look at the input circuit and the filament bypass and feed through.


Title: RE: L4B got easier to drive as contest went on.
Post by: KM1H on February 24, 2018, 06:09:22 PM
That amp is easily capable of 1200-1300W with 80-100W drive depending upon band and tube condition.

Monitor your bias voltage with no drive immediately after transmitting and also idle current next time.

Carl