A little while ago I became interested in digital modes available to Radio Amateurs. I made a posting of my initial adventures back here if anyone's interested :-
So that was reception sorted but I needed to sort out transmission........easier said than done(!)
As per usual there is always the obstacle of finding the time, proper time, time where you can actually think about what you're doing, without interruptions. Yeah, that precious time!!
Found the time, forged ahead, built a lead for transmit......didn't work???
Scoured the internet, loads of [ahem] 'advice'.
(I'm now sure 99.99% of advice given on the internet although well intended is 'horse manure' for phrase of a better word!)
One of the 'better' suggestions was to buy a newer radio as well as a commercial digital interface.....Ha!
Some of the other suggestions follow with the outcome of them...
"You need a USB/Serial interface to connect to the radio.
So I built a USB to RS232 interface, with opto-coupler switching to kick my old Yaesu into transmit via the PTT control on the rear. Much faffing with USB and setting the WSJT-X software to enable transmit.
Aha! With a click of the mouse I can make my old radio transmit.....but no digital modes transmitting?!?!??
"You need to have CAT control of the radio.
OK, let's see on that one, hmmm....my FT757gx had the very first type of CAT system. I can tell the radio what to do, (to a point - pretty much just which frequency to go to), but can't read anything back from it as it was never designed to do that. Despite building another USB lead, checking and rechecking the connections, software settings, etc. it refused to work!!
However, when I ran an old style serial 'Terminal' program and sent character strings to the radio as per the service manual the radio magically jumped to the frequency I programmed in! Success!
Well actually, no
It seems that although I was able to do this, none of the software writers of multiple versions of rig control CAT software systems were able or bothered to. Not for my 'vintage' rig anyway....
Not being a software writer myself, I gave that path up as a lost cause.
"Your audio drivers must be wrong.
Yep, that's Windoze mentality if ever I heard it, surprised no-one told me to 'turn it on and off again'. But I'm running a Linux system so in reality I shouldn't have these sort of problems. (Part of the reason I left Windows behind a long time ago!) Made a plea for Linux help and OMG got blasted with ALSA, PulseAudio and all sorts of 'technical' help....none of which worked.
"You need a 'proper' audio interface.
After hearing some arguments about common ground looping and utilising archaic 600 ohm 1:1 isolation transformers, (which we left behind with landline telephones some 40+ years ago!), I ordered some and built a new audio interface.....Nope! Still didn't work!
Just as well I've already lost most of my hair really....
OK, we've already lost precious time. Same as you lot reading this really eh?
Let's go back to basics.
Radio receives signals and software is able to decode digital signals - Check.
Radio goes into transmit when software tells it to - Check.
Radio sends signals from software whilst transmitting - Hmmm, nope!
Fire up the old Lowe HF225 SW receiver as a monitoring station, signal received and erm, no audio?
Plug in headphones to USB soundcard and fire up the WSJT-X software again - AAARRGGHH! Blasted with digital screams through the headphones straight into my skull!!
Audio works then
Why is no audio getting to the radio?
Check of the audio lead with a multimeter, (should've done that in the first place!). Right audio to Right audio, Left to Left, Ground to Ground - Check. Let's see, Right to Ground - no, Left to Ground.....Oh Bugger.
Seems my ageing eyesight and bear paw hands meant that the smallest strand of wire only visible with a magnifier is shorting the audio to ground. What a dumbfu......you get my drift.
As my radio input is a mono input the left and right connect together and as one side is grounded it also grounded the other. That'd be the reason for no audio then.
Problem fixed I plugged everything back together and......still didn't work. But I did receive a distorted audio signal on the Lowe. Unwired the archaic transformer interface - better audio but my TX seemed to flutter. A quick monitor of the USB TX interface showed that it didn't like being near RF so I simply unplugged it and switched the Yaesu to VOX mode.TAH-DAH!!!
FT8 howling 'music' heard on the Lowe monitoring receiver. Success!
Now lets unplug all this cr*p, take off the dummy load and reconnect the antenna.
All works, at long flipping last. Funnily enough none of the 'information' garnered or 'advice' given was of any help whatsoever.
Always worth checking the simple things first, but we always dig holes along the more complicated path.
Well, as this posting has already got quite long, I'd better leave that for another time.
All the best,
(Effin' son of a b')