John,
I had a look. The outside cosmetics are very nice, but the internal wiring
is kind of scary for RF. I suspect you have a lot of coupling between the
wires that are bundled together. In a more ideal setup, the PCB would have
been mounted directly on or very near to the two coils and tuning caps.
Here are my suggestions for troublehooting. Do them one at a time and see if
any of them make a major difference:
1) Remove the lowpass filter and mearure the RF output again . Maybe the
filter cutoff frequency is wrong.
2) Unbundle the wires and spread them apart. Does that improve anything?
3) Remove any interconnect wiring that isn't absolutely essential for RF
operation. Strap the switch lines to their proper state on the PCB & remove
lamp wiring. See if that improves things.
4) Measure the overall DC current and the DC current into the amplifier
stage only. When the amplifier is driven properly, getting 3 watts RF out
will require about 4-5 watts of DC into the final (Vfinal x Ifinal). If the
current is much too low, check out whether the oscillator stage is driving
it properly. If it's too high for the RF you're seeing, check the final
stage tuning and possibility of an oscillation.
Good Luck,
Joe
W3JDR
"John Sandin" wrote in message
...
Here's the link to my project website..
http://www.kcnet.com/~oyster/transmi...ansmitter.html
On Mon, 06 Oct 2003 02:56:38 GMT,
(John Sandin) wrote:
On Sun, 05 Oct 2003 13:27:59 GMT, "W3JDR" wrote:
John,
Can you post a picture of your unit somewhere(top and bottom views) so
we
can see what the PCB & wiring layout looks like?
I want to thank everyone. I never dreamed that I'd get so many great
responses, within a few hours of my original post.
I have put up a website with a link to the web page that inspired me
to do this. Below that are a bunch of pics of my project. Any
comments and advice are welcome.
I guess it would have been easier and even cheaper to buy a kit. But
I had fun building this, and I guess I'll have almost as much fun
rebuilding it.
-John Sandin KC0QWE
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-John Sandin KC0QWE
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