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Old October 30th 05, 01:44 PM
Scott
 
Posts: n/a
Default BFO, CW, sideband question

Yup, you've got it!

Now for the $64,000 question (which will only buy about 21,000 gallons
of gas these days!)...With these modern rigs, if I want to answer
someone calling CQ on CW, how do I adjust my radio to be on exactly the
same frequency as they are calling on (to conserve spectrum for other
operators)??? My "old" TS-520 has a "Tune" position, which sets the bfo
frequency exactly to the I.F. frequency (I don't have the service manual
in front of me, but follow the logic here). As I tune the radio (with
the VFO) in this TUNE position, when I have the VFO set to provide zero
beat, I will be right on his frequency since my BFO is running at the
I.F. frequency (9 MHz) and the combination of the far end transmitter
frequency and MY VFO frequency gives an I.F. output at 9 Mhz, so the
difference in frequency is zero. Whent I then return my switch from the
"Tune" position to the CW position, it shifts the BFO 800 Hz in SOME
direction (up or down, I can't remember and I don't really care!). Now
his signal mixed with my VFO and my now shifted BFO (which is now
running at 9.0008 MHz, for example) provides a tone of 800 Hz. Easy!

My "new" TS-690S doesn't have a TUNE position. The manual says to tune
for a tone frequency of 800 Hz (or whatever you have the "CW Tone"
frequency programmed into the radio). My question is how the $#@% do I
know when I have an 800 Hz tone coming out of my radio? Do they really
expect me to have a freq. counter hooked up to the speaker? I have
overcome this by setting the RIT to display either 800 Hz up or down
(can't remember which right now), turn on the RIT, zero beat they guy,
turn off the RIT and then I will be on his frequency. I find it's
easier to CALL CQ and let the other guy worry about getting on MY
frequency

Scott
N0EDV


Doug Smith W9WI wrote:



As I understood it, the decision to use different sidebands in the two
spectrum areas came from the design of some early SSB equipment. If you
used a 9MHz IF and a 5.0-5.5MHz VFO, you could cover both 80 and 20
meters without having to mess with heterodyne oscillators. But since
you'd be using addition on 20 vs. subtraction on 80, the sidebands would
flip.

(there's GOT to be a better way to say that but it's too darned early in
the morning!)