Hi Chuck,
I looked at your photos (nice work!) and it appears that you are using a
piece of Airdux with perhaps #12 size conductor. That is a mite small for 20
meters. I'd suggest upsizing the 20 meter section of the coil to at least 1/8"
(#8) or even 5/16" diameter.
The load padding capacitor as noted by several others is the wrong type for
this application.
A few options:
1. Change the load vacuum cap to 1400pF and eschew the padder.
2. Use a better quality padder.
A Jennings JSLF-450
or
Several Centralab (or equiv.) 850 series ceramic NPO's in parallel
or
An air fixed capacitor -- or perhaps a variable used as one.
or
A large transmitting mica -- This may be physically too large
3. Switch the existing padder so that it is only in circuit on 80 and
therefore only handles a minority of the current. Not truly optimum.
73 & Good morning,
Marv WC6W
-- "Partain, Chuck" <Chuck_Partain@maxtor.com> wrote:
I'll go peruse the archives again but I'm going to post this here anyway.
I noticed while on 20m tonight running about a kw that the tank coil was
getting
HOT, one of the wires connected to it (the 20m section) was turning a nice shade
of darker! the coil is warm.
also When I pulled the cover (I was looking to see where all the hot smell was
comming from)
I noticed that a doorknob cap I have installed next to the load vacuum cap was
also warm!
i'm using that cap to get me on 80m its in parallel with the 1000pf vacuum cap
everyone I talk to with it said they notice NO noticible difference when its on
or off only
a few s units higher! (no audible distortion)
the cap I am using is labelled n4700 591m 30kv 706h and has a c with an m
inside of it.
are these suitable for what I am doing? hell, its 30kv! why warm? what should I
be looking for?
the amp seems to load up pretty good into the vertical with an swr of less than
1.3 to 1
thanks for any help
chuck, ka1mwp
the schematic is at
http://home.comcast.net/~ka1mwp
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