Helge has done it again! He has shown us the benefits of homebrew CW. And he has done it with one tube. FB Helge.
Of course, I really liked the wooden box. His is a lot nicer looking than mine. I also liked how he carefully laid out the parts -- I seem to be stuck in my 13 year-old "build then design" mode. Helge's way of doing it is better: design, build. In that order!
Some will quibble about a lack of 700 Hz offset between transmit and recieve. With a VFO rig, this could lead to the stations chasing each other across the band. But Helge is crystal controlled here, so I don't see a problem. Is that right? Please comment below.
Thank you Helge for another great rig, a great schematic, and for showing us your obvious joy at reaching 400 km across the sea to your friend in Norway. FB!
Regarding the frequency offset, in my opinion
ReplyDeleteit is always necessary and easy enough to add,
but I operate all my radios often or else I
dismantle them and convert them into something
else.
However, it seems that lots of homebrewers just
build a radio to use once or twice and afterward
move on to the next project, so he has already
proven this radio works and he may have advised
LA5MT in advance to operate in split fashion.
Another answer might be that the resistors in the
power supply line that are switched between
transmit and receive cause a frequency shift.
We will have to ask Helge LA6NCA.
--Walter KA4KXX
Way to go OM! As for the rig, I would haver have thought of applying the received incoming signal to the oscillator grid, making it into a direct conversion mixer. No gain into just the one stage of pentode amplification. No way that should work. Hey, can't knock it till you've tried it (which I am to convice myself this works.). Keep up the very unconventional work. (KJ7UM, Grayson)
ReplyDeleteRight about the freq shift offset. The shift in receive/transmit components might be just enough to shift the oscillator frequency. Maybe.
ReplyDelete