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seem like my key wasnt wire right for my racal , it was on PTT and
GROUND, changed it to KEY and ground now it works great on USB/CW
and LSB/CW , but there is something I really dont understand CW on
the AM mode on the racal will only pickup on CW mode on the icom 703
radio cant hear it much on the AM mode on the 703, The only thing I
can think is that the racal set can tell someway if it is voice or a
key being used or could be that my 703 has a band filter of .500 for
CW and a 6.0k for AM ,thinking that the 6.0k is too much to hear the
code in the AM mode on the 703 icom. any feedback on this is
welcomed

Hi:

I recently was learning about this in relation to the PRC-104.

If a transmitter is in SSB mode and you press the mike PTT without any speech audio input there is no RF output.
In the PRC-104, PRC-74 and I'm sure many other radios there is a seperate CW keying line. When this line is grounded the radio inserts an audio tone into the SSB channel causing a single RF frequency to be transmitted. The actual RF frequency transmitted depends on the frequency of the audio tone, whether in USB or LSB mode and the RF frequency set into the radio.

There are two conventions for specifying the RF frequency of a SSB transmission. One is to specify the frequency of the missing carrier, which is the same as the carrier of an AM signal with the same side bands. If you use this convention and tune an AM signal then switch the receiver into LSB, USB or AM modes, in all cases you will hear the signal. This is the convention used on the PRC-104. You can hear the USB or LSB WWV transmissions by just switching modes.

The other convention is to specify the band center of the SSB transmission. The idea is that you are only transmitting a signal in some band and the signal energy depends on the modulation, so just specify the band center. I think this is how the ham 60 meter frequency is specified in the regs and that's why we need to tune to 5371.5 kHz instead of 5370 kHz, i.e. to get the transmitted signal into the specified band.

You will not hear a CW signal on a radio in AM mode. You need a BFO offset from the RF (or IF) CW frequency by the audio frequency you want the radio to produce when the CW signal is present. So you may need to adjust the BFO frequency on the 703.

73,

Brooke Clarke, N6GCE

--- In Racal-manpacks@..., Brooke Clarke <brooke@p...>
wrote:

The other convention is to specify the band center of the SSB
transmission. The idea is that you are only transmitting a signal

in

some band and the signal energy depends on the modulation, so just
specify the band center. I think this is how the ham 60 meter

frequency

is specified in the regs and that's why we need to tune to 5371.5

kHz

instead of 5370 kHz, i.e. to get the transmitted signal into the
specified band.

Hi,

if I remember correctly this is called "The Assigned Frequency"

and works very well with the idea of channelisation rather than any
idea of carrier frequency.

Michael