Thanks again to all. I'm going to take charge of this problem first
of all by rebuilding the project, using direct wiring, using the
layout recommended by QST, June 1967. Using this method, I can fit
everything into the just the lid section of my existing box and I
won't have to remake the tube socket holes in a new chassis. Based
on what everyone has said, I ought to get rid of all that loose wiring
anyway, prior to making any tests with a scope, which I don't yet
have. I want the thing to be well-constructed, to eliminate all that
unpredictability we've been talking about. I will also use only my 50
ohm dummy load for testing until everything's as good as I can make
it.

On 8 Oct 2003 05:40:24 -0700, (Ashhar Farhan)
wrote:

(John Sandin) wrote in message ...
Regarding the 3-watt transmitter I'm building (and having trouble
with), here's an update.
...

john,
a receiver will probably report all the harmonics of the crystal. so
that is not really a big deal. almost all the harmonics will also
sound pretty powerful and equal to each other in the HF receiver
because the recevier's AGC will boost the lowering outputs to a higher
level.
the output at 3.5mhz can be easily explained by a receiver shielding
deficiency. what i would really suggest to you is to TAKE CHARGE. i
mean, figure out exactly what is going and how.
do you have access to an oscilloscope? a single oscilloscope trace is
really worth a thousand blind trails. failing which,
i suggest that you should first make yourself some test instruments. i
would highly recommend a wavemeter. it requires about 5 components (a
couple more if you want to build a GDO-cum-wavemeter). A single coil
should cover most of the HF band of interest to you. then ...
rebuild the transmitter from scratch, keep everything at 50 ohms
impedance. refer to EMRFD for guidlines. then ...
don't push too much gain in each stage. It is actually easier to debug
and build a transmitter with more stages having lower gain than trying
to push maximum out of fewer components. finally ...
shoot for about 7 watts of output. An 80 cent IRF510 should easily
give you that much. use the wavemeter and the a power meter to measure
the harmonic outputs. But frankly even if you are pushing out 50% of
the energy in fundamentals, then political correctness aside, you
should be able to make contacts. QRP of single watters are best left
to old war horse like W7EL. it is tough for a novice to get through on
a single watt being rock-bound.
i would also suggest that you hook up with a ham down the block to be
able to monitor your signal. then another across the city ... then
another across the state...
- farhan


-John Sandin KC0QWE

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