Re: Ramsey Amps?

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From: Richard G. Kellner (kellner@usa.acsys.com)
Date: Fri Aug 18 1995 - 17:41:56 EDT


> Date: Tue, 15 Aug 1995 20:48:23 -0400
> From: "John F. Woods" <jfw@jfwhome.funhouse.com>
> To: RHenry3860@aol.com
> Subject: [2547] Re: Ramsey Amps?
> Message-ID: <199508160048.UAA03016@jfwhome.funhouse.com>
>
> > Has anyone out there ever used the Ramsey QRP amps?
> > They put out 20 watts with 1/2 to 2 watts in.
> > I was pondering getting the Sprint II for 40m by oak hills and the Ramsey
> > Amp. I would have 20 watts or the price of the 5 watt version of the 40
> > meter radio from OH.
>
> If its quality is up to the usual Ramsey standards, you'll be lucky if 5 of
> those 20 watts are actually in the intended amateur band...
>

I have within the last two weeks built the Ramsey QRP amp for 20m. The
kit went together very quickly, although two of the output low pass
filter caps were the wrong values, presumably the ones for one of the
other bands. Ramsey promptly replaced them.

The instruction manual was totally wrong for adjusting the bias. Looking
at the schematic, I saw that there was no way the procedure could work. I
called Ramsey and they said yes, the manual is wrong, and actually you need
to do ...

The amp is putting out 4 watts of filtered 20m signal with 1 watt in
at 12.6 volts DC. Putting the scope on the circuit, the two halves of
the push-pull circuit are not contributing equally; one side is way down.
I will try to pinpoint the problem this weekend, but I'm guessing that
even when both sides are fulling contributing I'll only get at most 8
(twice the 4 I'm getting now) watts. Not what I expected based on the specs.

The bright side is that technically I'm still running QRP at 4 watts!

73 de Rich W5RXP.


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