Message-ID: <001401c4fb53$59f6f270$e901a8c0@bob2l2u6k2n1g3>
From: "Vernall" <vernall@xtra.co.nz>
To: rsgb_lf_group@blacksheep.org
References: <E1CpPKZ-0001YH-2V@www9.emo.freenet-rz.de> <006901c4fa2c$fc275e40$0702a8c0@parissn2> <41E847FE.8030107@usa.net> <001101c4faf8$ec28b260$53c9c354@pc2> <41E90E58.4020105@freenet.de> <41E91721.6060908@usa.net>
Date: Sun, 16 Jan 2005 11:41:25 +1300
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Subject: LF: CW-R and IF shift
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Alberto, Wolf and others,

>  I concur completely with what Wolf has said. Both Yaesu and Kenwood (and 
> I suspect Icom too) have the
> rig switched to USB when using CW.

No, it seems Icom designs use LSB for the "CW" mode.  Certainly the Icom 
IC-R75 needs to use CW-R to faithfully translate the RF FSK to AFSK.

It is easy to test a receiver, by using a signal generator as a test signal. 
Leave the receiver tuning alone and adjust the frequency of the signal 
generator, and it soon becomes apparent whether CW or CW-R setting is 
appropriate for the data mode of interest.  It is mentally more challenging 
to use an existing carrier (or a fixed frequency signal generator) and tune 
the receiver to observe the change in sidetone, as that activity involves an 
"apparent reverse effect".

Receivers with IF shift can slew the narrow IF passband (of a so-called CW 
filter) to the appropriate IF centre frequency for a data mode such as 
Jason.  On receivers that have no readout of IF shift, it is a bit more 
tricky to set it for receiving a DX signal, as the desired signal (as 
detected and sent to the loudspeaker) may not be audible in the noise, in 
which case it is essential to pre-set the dial frequency and IF shift to be 
right on the expected frequency to be received.

73, Bob ZL2CA