Saturday, August 14, 2010


I was up early and tuning the band and heard HL0NHQ on 40. It was perfect gray line time but the storm QRM kind of precluded my contact. I was able to hear him but he was dish water weak so I decided to make a blog entry

I got into a recent pissing contest over on EHAM with old Stan K9IUQ regarding the "lag" of the CW side tone. A fellow was interested in the F3K and wondered about the "lag". Stan is a bit of a misanthrope who likes to knock the F5K all the while claiming to be objective, so I decided true objectivity could be had by publishing an audio clip the demonstrated how the F5K actually sounds

The reason the Flex radio can do so many amazing thing is because after the signal hits the antenna there is a whole lot of computer processing going on before the audio hits your tympanic membrane and courses into your metenchephalon headed for your consciousness. In the old SDR-1000 days the lag was substantial. There was virtually no way you could use the sidetone in the radio to send code because what you heard in your headphones was "lagged" by at least the length of a dah. It was maddening. What I did to over come in in those days was to have the Flex audio mixed with the sidetone output of my keyer on a 3 channel stereo mixer so I could hear the radio and hear the sidetone from the keyer in the same headphones. That is basically all over, at least to my ear.

After all the kvetching from Stan I decided to make a recording of what my radio sounds like so people can listen for themselves and make a judgment. My keyer is set for 32 wpm


What you hear is a mic recording of the sidetone of my keyer (the 500hz note) and the 350hz note of the side tone in my F5K I have my F5K set for

Audio buffers of 512 and panadapter bandwidth of 96K My DSP transmit buffers are set at 512 and my receive buffers at 4096

I have my transmit delay set to 60ms and you can hear the transmit relay clicking in the background as I send test. This gives you an idea of what hearing between words means, as you can hear the relay drop between words and letter sequences. With the relay set to this delay My rig is semi-breakin and I can hear between words in a normal 25+ wpm qso. The keyer is my USB winkey and I send the transmit signal into PSDR over a serial port into the computer. I do this so I can have 2 paddles attached to the radio, one to the keyer and one to the back of the radio. This has been my keying methodology since the SDR-1000 days.

So now you can put to rest all the opinions from the know it alls and make your own decision regarding the lag issue and the Flex line of radios I have no problem using the sidetone in the radio to send code up to 60 wpm which is the upper limit of my keyer not to mention my addled old brain and my creaky old joints. You can also hear that I have none of the so called "squelch tail" problem with these settings. The audio is clean with no pops added. I don't have a very fancy computer nor do I bother with worrying about latency. My computer is a shuttle core 2 quad and 3 gigs of memory