Hi everyone,
I've finished (for now) my experiments in getting 10 meters on my
K1. It seems to be working pretty well, both on receive and
transmit. I have it up to about 4.5 watts output. I'm sure that can
still be improved but I've decided to give it a rest for now.
Here are all the component values I have used, with 10 Meters as Band
2 of a 2-band filter board. Where I've used two capacitors to make
up the final value, I've indicated that, along with the value I would
have used had I had the capacitors handy.
C6, C10 = 90pf (68 + 22 in parallel; intended to use 82pf)
C7, C9 = 47pf
C8 = 1pf
C16, C20 = 220pf
C17, C19 = 33pf
C18 = 2pf (1 + 1 in parallel; intended to use 1.5pf)
C24, C26 = 68pf
C25 = 150pf
L11, L12 = approx. 0.26 uuH (8 turns of #26 on the supplied yellow
cores)
X2 = 36.000 MHz fundamental
Three additional modifications have been made to the radio to
increase the output on 10M:
#1: 220pf capacitor added to filter board, on the top side, on P2
between pins 7 and 8. This could also be done on the RF board, at
pins 7 & 8 of J7. I had more clearance though on the filter board.
#2: On the RF board, R11 has been changed from 82 ohms to 33 ohms,
to increase the gain of the Buffer.
#3: On the RF board, T3's turns have been compressed as tight as
possible. The windings now occupy about 130 degrees of the core.
Experimentation showed that the tighter the windings, the higher the
output on 10 meters. This did not seem to affect the other bands at
all, i.e. no noticable effect even down at 80 M. Next time I feel
like experimenting, I might try rewinding T3 to make it even tighter.
As I said, with those modifications I'm seeing about 4.5 watts
output. The bandwidth is excellent; I've got my K1 set to tune about
270 kHz (using 200pf for RF-C2) and I'm seeing the full output power
all across that range. I've had good success copying a couple
beacons, from 28.217 to 28.258.
The only thing I haven't really addressed yet is how the KAT1
performs with 10M. I tried it briefly and found that the output
power seemed much lower even with the KAT1 set to bypass (ATU set at
CLP) but that may just mean that the KAT1 needs to be recalibrated
for 10M.
Hopefully this info will be of use.
73 de Stephanie
va3uxb
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