I found NOS Soviet block screw mount micas on ebay that looked like they
would handle QRO and have three pairs in series to cover the band with
shorting relays - all shorted = 1820 then each step (2 short, 1 short,
all open) adds 50KHz. 85' to top, 2x 30' hat and 8 10' elevated 125'
radials. So far no problems. Relays are PCB 8a, 5KV coil isolation,
they only see 350v or so and never hot switch. Ok so far, up 2 years but
I think the top is a little too close to the tree. The tree guy will
fix that next visit.
Grant KZ1W
On 8/2/2015 17:10 PM, Steve Flood wrote:
My top-loaded vertical needs a series 260pF capacitor at the feedpoint to
match the 53 + j335 impedance (1.825 MHz) to my coax feed.
I have a few different air-variables I could use, but I was wondering what
sort of fixed capacitors would be suitable in this application.
Max power is 1500w. I have doorknob caps but they don't have current
ratings marked on them.
Thanks,
Steve KK7UV
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