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Author Topic: Zero Beat FT-840  (Read 1149 times)
KC0SOG
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Posts: 68




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« on: November 24, 2004, 06:22:21 AM »

I'm about one-inch away from making my first CW contact. I'm confused on how to zero-beat a station using my Yaesu FT-840.  The manual explains the reverse CW feature and the default USB setting, etc, but just don't get it. I would appreciate the help.

tnx es 73 de Doug, KC0SOG
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WB2WIK
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Posts: 20611




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« Reply #1 on: November 24, 2004, 11:21:57 AM »

You don't "zero beat" with an FT-840.

You "net your frequency" to the other station's frequency, if you want to call somebody.  That's very easy to do.

1.  Hit the key and listen to the sidetone generated by your rig in your headphones.  It's probably 600 to 700 Hz or so, and possibly can be changed with a menu setting.  But just listen to it for a second.

2.  Tune in the station you want to call so he sounds like the same tone (pitch) in your headphones as the sidetone you just listened to.

3.  You're done.  That should get you within probably 50-100 Hz of the other station's frequency without taking any time or effort to do anything other than match pitches.  That's absolutely close enough, 99% of the time, for the other station to hear you just fine.

4.  If you want to get even "closer," you can...one easy way to do this:

When you're listening to a station you'd like to call, turn your output power down to zero, or prevent transmitting altogether, and key your rig to provide a sidetone in your headphones.  Tune the other station in (using your VFO dial) until he sounds *exactly* the same pitch as your sidetone.  When you get very close (within a few Hz), you'll hear a beat note between your sidetone and the other station's signal.  When that beat note becomes so low in frequency that it appears to go away, you're extremely close now, probably within just Hz of his frequency.  To get any closer is unnecessary and a real waste of time.

Of course, when you call CQ, the frequency you're on isn't critical at all, other than:

1.  Be in the band you're licensed for.
2.  Don't call CQ on a frequency where you hear other activity.

Always send, "QRL?" before calling CQ.  Wait 10 seconds to see if anyone replies.  I usually do this twice: QRL? <wait 10 seconds>  QRL? <wait 10 seconds> and if I don't hear anything, I feel free to call CQ there.  If somebody wants to yell at me later, fine.  They had their chance when I called "QRL?"

73 & C U on the bands...

Steve WB2WIK/6





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WA0LYK
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Posts: 85




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« Reply #2 on: November 24, 2004, 07:53:00 PM »

Let me change Item 4 above just a little.  With most rigs, if you put them in cw mode but keep the VOX turned off they will provide a cw sidetone when you operate your key but the rig won't tranmit.  To actually transmit, you have to turn VOX on.  This method can be used for code practice or to zero beat a station as described.  You may have to decrease the monitor/sidetone volume to hear the other station, if there is a separate control for this.  

I am not familar with your rig, but a lot of them operate in this fashion.

The only kicker is if you are using a keyer, not all of them have a way to hold the "key down" while you do this.  Without it you will generate dits or dahs.  You can still get pretty close by "zero beating" with dits or dahs.

The only other possible problem is if the Kenwood has a separate BFO to generate the actual cw signal.  My Icom's have unique BFO's for USB, LSB, and CW.  This BFO may not be aligned with your sidetone so your actual transmit signal may be off a little.  You could tell this if you have a second receiver available.

Jim
WA0LYK
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KC0SOG
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Posts: 68




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« Reply #3 on: November 25, 2004, 05:47:39 AM »

Let me clarify two things on my FT-840.   Yes, I can adjust the sidetone.  No, I don't have VOX.

So, I will have to key into my dummy load to hear the tone (700hz) and switch back to the antenna to compare it to the incoming signal.  But, only until I memorize 700hz sidetone pitch.

That should be easy since, I practice using 700hz on my G4FON software.

When I get better at CW, maybe I'll upgrade to a rig that is rich in CW features.  I've been making a wish list...Internal keyer, VOX, spot tune, etc...

Thanks for the help,
Doug  KC0SOG
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KC0SOG
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Posts: 68




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« Reply #4 on: December 30, 2004, 05:03:15 PM »

Just a quick update.

I conducted my first CW QSO today by calling CQ on 7102. I had a good 30 minute rag chew with a patient and nice ham.

The efficiency of CW amazes me. I was able to pick his signal out of an S6 noise level at 4:30 CST this afternoon and copy almost all of it.  I worked him with about 30 watts.  On SSB I would not have had a chance.

Thanks for the help and happy new year,

73, Doug KC0SOG.

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AA1UY
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Posts: 17




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« Reply #5 on: January 29, 2005, 09:53:07 AM »

I've configured my Yaesu FT-840 so that the key beep frequency is the same as the side-tone frequency (I like 600 Hz). This is easily done from the front panel following instructions in the manual. That way I just have to press the CW/N key (twice, to toggle back if you have a filter installed) to hear what a 600 Hz tone sounds like. Then I can tune until the station I'm trying to work sounds the same.
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AA1UY
Member

Posts: 17




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« Reply #6 on: January 29, 2005, 09:53:47 AM »

I've configured my Yaesu FT-840 so that the key beep frequency is the same as the side-tone frequency (I like 600 Hz). This is easily done from the front panel following instructions in the manual. That way I just have to press the CW/N key (twice, to toggle back if you have a filter installed) to hear what a 600 Hz tone sounds like. Then I can tune until the station I'm trying to work sounds the same.
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