[CQ-Contest] Band edges-measured.

[George, W2VJN]

Here is what really happens with a 1000MP when the tx output is
measured on a counter.

There are two settings in menu item 3-0.  CARRIER and OFFSET.

1.  Setting is CARRIER:

Dial reads 7002.00
Mode is USB CW,  Tx output is on 7002.00
Mode is LSB CW,  Tx output is on 7002.00

This is safe.  With a properly functioning radio that is
calibrated and has keying rise and fall times about 2 or more mS,
I would go within 500 Hz or so of the band edge (being very
safe).

2.  Setting is OFFSET.

Dial reads 7002.00
Mode is USB CW, Tx output is on 7002.00
Mode is LSB CW,  Tx output is on 7000.80  (Pitch control is at 1
O'clock.)

This is not safe if you are in the habit of switching from USB to
LSB when running stations close to the band edge.

NOTE:   With 3-0 set to OFFSET when you are operating in USB and
the pitch control is turned, the LSB frequency changes.  If you
switch to LSB and turn the pitch control, the USB frequency
changes.  You must watch the display each time the mode is
switched.

Other radios may function in a different manner.

George, W2VJN






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>From K0HB at USWEST.NET" <K0HB at USWEST.NET  Mon Dec 18 02:21:35 2000
From: K0HB at USWEST.NET" <K0HB at USWEST.NET (Hans K0HB)
Date: Mon, 18 Dec 2000 02:21:35 -0000
Subject: [CQ-Contest] Band edges?
Message-ID: <01C06899.95B7A760.K0HB at USWEST.NET>


Pete Smith  wrote:
 
> I have long understood that the frequency displayed by a modern
> transceiver is the frequency of the suppressed carrier.  If you 
> are operating on USB CW, then the carrier is shifted up (for 
> example, 800 Hz) into the passband of the crystal filter, and 
> the actual center frequency is display +800 Hz.


> Am I wrong? 
> 
> 73, Pete N4ZR

Depends on what "modern" means.

If "modern" is a SB-102, then you are correct.  An audio
tone ("offset tone", 800 Hz for example) was injected into 
the balanced mixer and the resulting signal was that amount
above or below your "window frequency".

Most modern equipment is not that crude. My IC-775DSP, for example,
displays the frequency of the transmitted signal (there isn't
even a "suppressed carrier" involved).  If my "window freq"
is 14.000.100, then that is where my signal appears on the air.
There will be some modulation products (sidebands, if you wish)
on either side of that, depending on keying speed.  Unless I
am overdriving my exciter or amplifier, it is entirely safe
(and legal) to operate 100Hz from the band edge.  (Presuming
I trust my last WWV calibration!)

73, Hans, K0HB





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