zero beat ssb

(1/1)

Scott Dordick:
I have had my general license for about 5 days now. Yesterday I particapated in my first HF SSB (40 meter) net. I was told I was below frequiency and to zero beat. I was able to get on frequiency by dialing up my frequiency until net control said I was on. Then dialing my receive back with the RIT. My rig is a kenwood TS130S. How do I zero beat properly on SSB?

Pete Allen:
HI: First: "zero beat" means beating a station you are listening to's carrier against your transmitter's local oscillator. As you get closer and closer the tone you hear will go from a whistle to a growl to a thump-thump-thump. When the thump stops you are "zero beat," exactly on the other station's transmit frequency.

But SSB has no carrier to beat against. So you literally cannot zero beat an SSB signal. The best you can do is what you did do. Tune your reciever until the other station sounds as natural as possible and call them.

If they say you are "off frequency" for some reason, perhaps your voice is higher or lower in pitch than they expect it to be, do exactly what you did. Tune them in as best you can and adjust your RIT until they sound good to you.

However, if you keep on having this problem in general hamming - your BFO or your LO may have gotten a little off frequency off over the years and your rig might well benefit from a professional realignment.

73  Pete Allen  AC5E

Gary McAdams:
The answer here is simple: Leave the RIT off until needed.

Tune in the net control until they sound natural. You will be mostly zero-beat at that point. Then, use the RIT only to tune in the next fellow who comes into the net. Leave the transmit VFO on the net frequency.

BTW on the 130, the RIT is OFF when the button is out.
The RIT LED should light when the button is pushed in. This indicates the RIT is active. You should leave the RIT in the off position when initially tuing in a station.

73 Gary WG7X

James Haboustak:
Hi Scott,
     Congratulations on your general ticket.
   Something you can try as an experiment is to receive WWV with your rig set to SSB. While they are transmitting a tone, toggle your receiver between USB and LSB. The tone you hear should be about the same 'pitch' on both side bands. If there is a difference in the pitch, tune your rig up or down until there's minimum difference between USB and LSB.
   When the pitch is approximately the same, note the frequency on your rig's display. The difference between the WWV frequency and the display on your rig should give you a ballpark estimate how far (if any) your receiver differs from the actual frequency.

Have fun...Jim

Giancarlo Moda:
Welcome in the ham fraternity.

I do not know the TS130 but it is a good rtx.
One of the problems with old RTXs is that the RTI center pot position may be off respect the TX varicap voltage control, usually a fix partitor. You should look at the circuit diagram if there is ore internat trimmer(s) to adjust. You will need a frequency counter to do the adjustment. In case there are no trimmers, and the LO chnage frequency between TX and RX, you can center the pot and then reposition the knob or try to add a resistor in paralle to one of the resistors in series with the rti pot till you find the right varicap voltage.... and enjoy the HF bands

73
Gian
I7SWX
F5VGU
W1-I7SWX

Navigation

[0] Message Index