Hi Folks,
Joined the list a couple of weeks ago
amd enjoying reading all the postings but this is my first
posting.
I am planning to use my Elecraft K2 to
drive a homebrew transverter to give me a 500khz capability. I have the
transverter interface board in the K2 so have a 1mW output
available.
So far I hace lashed up a 28Mhz xtal
oscillator and a home brew diode ring mixer. Feeding these through a G0MRF 7
element Low Pass Filter I tested it the other night and it works ! Wow.
Nice clean cw and ssb on 500khz (feeding directly into my receiver....probably
the first and last time I'll hear ssb on 500khz !!) Amazing carrier
suppression on ssb - really impressive for 4 IN4148 diodes and a couple of
FT50-43 cores. Plenty of attenuation of 1000khz and 1500khz harmonics. It's
looking good !
Just tried it on receive and it does
work but signals very weak. With the K2 pre amp on I can hear MSF 60Khz at
S1 , Loran 100Khz at S4, BBc R4 198Khz at S9, plus a few other data type
sigs below 150khz. Heard nothing on 500Khz . I can hear a strong intermittent
data type signal on about 518Khz Plenty of noise when I connect the
antenna though. Looks like I may need to work on the antenna and maybe some
receive amplification .
I'm thrilled with all this so far
but now I need some help with the rest of the system.
So a few questions for you all, and any
ideas and suggestions gratefully received !
1) Can anyone point me to any designs
for a pa suitable for 500khz. Something around 5 - 10 watts output from about
1mW input would be great. I am not very knowledgable on electronics but I love
tinkering so something which is easy to get going would be good. I imagine at
500khz it should not be too difficult.
2) Has anyone on the list used a K2
with the transverter board to drive a transveter ? I can get a full 1mW tx
output into a 50 ohm dummy load (as per the construction manual) but when
driving my homebrew ring mixer I can only get about 0.3 mW maximum. I wonder
if there is an impedance mismatch which is loading the K2 output. The K2
is connected directly to the mixer. My mixer has six trifilar turns on a
FT50-43 at each end. It clearly works well but I think I'll need to get the
level up a bit at some point.
3) Thinking ahead to antennas.....I'll
need to do something to resonate my 180 ft Inv L . I 'll probably stick a big
loading coil in it somewhere but I have no idea how much L I'll need . Is
there any software out there which will help me with this ?
Meanwhile I'll press on with the band
pass filter which is not working so well . Time for a tinker !!
TIA
73,
Vic GW4JUN
Halkyn North Wales
IO83JF
