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Old November 24th 08, 04:03 AM posted to rec.radio.amateur.homebrew
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Posts: 242
Default SWR meter

On Nov 23, 7:56 pm, K7ITM wrote:
On Nov 23, 10:07 am, highlandham wrote:

In the 78 issue there is one as you describe. The broadband torroid sensors
are about standard in the autotuners and in some radios because they tune up
at low power. They are small and don't add much inductance. You might even
build it into a qrp rig and use a multi function meter scrapped out of an
old tape recorder or a led bar graph.


================================
High intensity LEDs (for example those as used in traffic lights ,225 ea
per light) already light-up at 45 microampere and hence can be directly
used as a reflected power indicator instead of a meter.


Frank KN6WH


Cool idea, Frank! Should work fine at low frequencies, but beware
that the junction capacitance of high power LEDs can be pretty high so
they likely wouldn't be great at higher frequencies. I just measured
some low power ones a few days ago at about 20pF, which is about 265
ohms reactance at 30MHz, not bad at all, but wouldn't be so good at
450MHz.

Cheers,
Tom


I'm a looking at my tentec 1202 swr kit I a built. They usin' dual
stacked iron toroids just large enough ID to pass an inch long piece
of RG174 coax and 10 turns of 26 AWG enamel wire.
 
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