>In searching for some answers to problems of low rf output on 10 mtrs. I ran
>some tests on the plate choke and here's what I found. With ends shorted I
>found a deep dip at 20.8 mc.- -34.00 ---and 25 5 mcs.
> With the ends open I found deep dips at 20.5 and 27.00 mcs.
27MHz is within 4% of the 28MHz band.
>My handbooks
>all say to short the ends for these tests but say nothing about the results
>with the ends open.
That's seemingly because less than a few of the guys who wrote about
amplifiers actually built 'em. I too read the handbooks, and it took the
experience of an 8169 choke fire to tell me that checking the choke
shorted was not a slam-dunk. It seems to me that checking the choke
wired in place is more likely to result in less smoke.
> what I need to refresh my feeble brain is whether any of
>these findings could result in low power on 15 and 10 mtrs.The 6% of freq.
>that I often hear seems to say "not to worry", but does anyone have any
>comments on my findings ???
The +/- 6% does not apply to shorted chokes -- perhaps because chokes
are usually not operated into a short ? However, the open test on the
bench will get one into the ballpark. The best test is wired in place.
have phun, Carl
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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