On 28/12/2020 02:56, Jacques Pecourt
After much help from you all in this
Group, I finally got my TS590-SG running very well however I
noticed strange behaviors on the subject. Following the Kenwood
recommended settings I ticked the "Fake it" option in the Radio
tab. No issue there until recently when I chose to park my Red
post above 2200 (trying to avoid the crowd below), the CAT
changed the VFO by +500 hZ on transmit. Exactly what should
happen as very well described in the "FT8 hinson guide" and
returned to 10,136 on receive. VFO A in use did not go to B
during transmit (as I read some other places it would do) The
change in frequency was going from 10.136.0 to 10.136.5.on
the radio display, 10.136.000 to 10.136.500 on the computer
screen. Then I noticed several changes on the computer screen.
# 1. The green post mark remained
under the red one despite the fact the fellow who was answering
my CQ was way up the band (2400)
# 2. The Tx and Rx markers (just below
the Decode Tab) became grey out, both indicating my frequency
(2250). They were like disabled. Kind of annoying as I like to
see if the frequency of my correspondent is more or less clear.
I was only able to move them back (after the 73 completion TX)
up or down using new values by Ctrl + click or Shift + click to
new spots. Reading more details in the "FT8 tips" I see what
is happening, (shift of the generated audio down or up) well
explained and the remark at the bottom of the page "don't
panic....it's all under control".
So my questions are: Is this behavior
of the posts normal ? Should I keep this "Fake It" permanently
even if I choose to transmit below 2200 and above 1200 ? What
about the third option "Rig" ?
I tried both "Fake It" and "None"
within that range and don't seem to have any exchange problems.
The green post moves to where the station responds.
Last comment: I love that 590 G....what
a difference with my old boat anchor !
both "Split Operating" "Rig" and "Fake It" have the same purpose
which is to optimize your transmitted signal in two important
ways. The first is to allow you to transmit at any audio offset
without regard for the bandwidth and shaping of your transmitter's
Tx SSB filters. The second is to ensure that you signal is clean
and clear of any audio harmonics that might have been generated by
over-driving the transmitter modulator, which is easily done and
hard to detect without a second monitoring system or expensive
test gear. It does that by ensuring all harmonics are placed above
the low-pass cut-off frequency of a typical transmitter SSB
"Rig" is always preferred if it works reliably, particularly if
you are using any sort of VOX or other external keying including
audio interfaces that generate a hardwired PTT signal from
observing the presence of Tx audio (the SignaLink USB interface
being an example). The reason the "Rig" setting is preferred is
that there is no ambiguity between the timing of the rig switching
to SEND and the adjustment of frequency necessary to do what this
option requires. "Rig" uses SPLIT on the rig which implicitly
synchronizes the transitions to SEND and back to RECEIVE and the
necessary frequency changes. OTOH "Fake It" relies on the
sequencing of commands sent to the rig, which is OK if they all
use the same channel, i.e. CAT control of frequency and PTT, but
are potentially ambiguous if VOX or hardwired PTT driven by a
serial port RTS or DTR signal (possibly with an external sequencer
including deliberate delays to protect pre-amplifiers and relays)
In summary, if you are using any mode that requires varying Tx
audio offsets, or Doppler correction for EME operating, then
"Settings->Radio->Split Operating->Rig" is always
preferred. "Fake It" is an acceptable alternative if you have a
dual receiver rig and wish to use the second receiver for other
purposes, or if CAT control of SPLIT does not work correctly.
"None" should be considered a lowest common denominator default to
be avoided unless it is really the only one that works.