My experiment goal was to see if I could get my NCL-2000 amp to load on
30 and 17 meters without changing the existing bandswitch and tank
circuit wiring.
I figured that the 40m and 20m bandswitch settings would tune 30m and
17m respectively if I could reduce the (effective) inductance of the
tank coil for those two bandswitch selections.
To operate on 30m, I shunt out approx 3 turns of the coil.
To operate on 17m, I shunt out approx 1 turn of the coil.
I shunt out the coil turns at the tuning capacitor end of the coil
rather than at the bandswitch end of the coil.
The tank coil wire is very heavy gauge (maybe 2 or 4).
All other tank circuit wiring is about 14 gauge (solid).
So, I first tried to use 14 gauge (solid) for my shunt wires - with
alligator clips at each end.
The shunt wires got VERY hot during operation (enough to discolor the
alligator clips due to the heat).
I went to 10 gauge solid wire with fresh alligator clips and, although
the wires still got quite hot, the clips didn't become discolored.
So, at this point I thought I'd pass the info to anyone on the list that
might want to comment or offer advice as to whether or not I'm on the
right track.
Since the bandswitch tap wires don't heat up nearly as much as my shunts
at the other end of the coil - I wonder if it's because there is much
higher current where my shunts are? i.e., like the way current and
voltage change at different points along a feedline?
Those who are annoyed by my ignorance may flame away, but I'm just
hoping others may help me shed some ignorance.
If your help indicates that the mod doesn't have any serious drawbacks,
I will add an 'auxiliary' bandswitch the switches the expermental shunts
in and out (switching bands to and from 30m and 17m with manual
installation of clip shunts is nerve wracking and tedious to say the least).
Thanks, and 73
frank w0ecs
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|