Tom,
Can you show how you added the 160M ruskie padder and the switch?
Hi John,
On 160M only, I don't have enough C2 loading capacitance available, just 2,000 pF. (vacuum variables) The pi-net on 1.885 requires 3,000 pF for the 20 uH coil I have. I need more C2 or L, take your pick. So I decided to keep the L1 at 20 uH and add some more C2. The higher bands, 75-20M have plenty of range for Q=12.
So, on 160M I usually add in a fixed capacitor of 500-1000 pF in parallel with the loading cap. I use either a relay or just a 20A 120V large toggle switch with the shortest leads possible, right near the loading cap. 160M is very low loss band, so is very forgiving when the Q is somewhat higher as a result.
Do not use doorknobs for this high-current use, but rather, capacitors that are rated for at least 5A or more at 160M. (6A at 50 ohms is about 2500 watts, so there is overkill) The common dark brown .001, .0005 mica capacitors about 1.5" X 1" X 3/8" commonly found in flea market boxes, used for years in military rigs are usually marked for current. I've never blown one up in loading cap service, though I have popped door knobs there.
Use thick wire.
** I will have some new pictures soon of the whole rig and this cap padder. The wiring is almost done except for the tube sockets and modulator iron. I silver plated the tank and RF final copper straps. Lots of cosmetic improvements to make this new 813 rig look FB and talk whirlwide. Got the window glass and will make up some panel labels soon. It has gone from an Ugly Duckling (see first pics posted here) to Hollywood, quite a looker, rivaling Fabio, Rico Suave and Dr. Love. Caw Mawn.
T
