[Amps] HF-2000 amp problem?

[Pete Smith]

I think the opposite is true.  But is there anything truly wrong with 
tuning and loading for maximum output at a given drive level?  Then if you 
want to improve IMD, isn't the conventional wisdom to increase loading 
(turn clockwise) a little further so that output drops off a couple of percent?

73, Pete N4ZR

At 09:54 AM 4/16/2007, k7rdx wrote:
>Would not loading heavier cause the grid current to be even higher?Jim..
>----- Original Message -----
>From: <TexasRF at aol.com>
>To: <Paul at PaulFerguson.us>; <amps at contesting.com>
>Sent: Saturday, April 14, 2007 9:28 AM
>Subject: Re: [Amps] HF-2000 amp problem?
>
>
> >
> > Sounds like you need to increase the drive to 50-75w like 20m and load
> > heavier (less load C) for maximum output.
> >
> > If this scares you, load heavier first and then increase the drive  power.
> >
> > 73,
> > Gerald K5GW
> >
> > In a message dated 4/14/2007 10:25:05 A.M. Central Daylight Time,
> > Paul at PaulFerguson.us writes:
> >
> > I have a  10-year-old QRO HF-2000 amp. It has two Amperex 3-500Z
> > tubes. You can see  info on it at: http://www.qrotec.com/
> >
> > It used to output 1,000 watts or  so on all bands. Now it outputs
> > 1,000 watts up to 20 meters, but only  about 500 watts on 17 meters
> > thru 10 meters.
> >
> > On 20 meters and  lower, grid current runs about 150 ma and plate
> > current about 500 ma.  Plate voltage is about 2,800. Input power runs
> > 50 - 75 watts.
> >
> > On  17 meters and higher, grid current is about 100 - 150 ma and plate
> > current  is 250 - 300 ma. A small increase in input power gives a
> > large increase in  grid current and little additional output power.
> > Input power is 30 - 40  watts.
> >
> > The amps tuned inputs seem OK as the transceiver sees an SWR of  1.1 -
> > 1.3.
> >
> > All measurements were taken using a 50 ohm dummy  load.
> >
> > Any ideas as to what might be the problem?
> >
> > 73,
> > Paul -  K5ESW
> > Raleigh, NC
> >
> >
> >
> >
> >
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