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
