[Kenwood] modifying the TS 430S for use with the SM 220 & BS 8

[Alan Wolke]

The rigs listed in the SM-220 manual are those that were available at
the time when the SM-220 was new.  This is why you don't see any newer
rigs listed, even though it can be used with them.

The two IF outputs on some of these rigs are for two different
purposes.  On the TS-830S, the IF1 is the wideband, low level output
taken immediately from the mixer before any filtering.  This is the one
that is used for the bandscope function (because you don't want a
filtered signal for bandscope, or you wouldn't be able to see adjacent
signal activity).  The IF2 is an amplified and filtered (narrowband)
output, taken after the 8.83 IF filter.  This output is used to monitor
the signal envelope of the received signal in the normal "oscilloscope"
mode of SM-220 (or any oscilloscope), and it is the one that goes into
the V input of the scope.  The resulting display is very similar to what
you see when monitoring your own TX signal in the MONItor mode, except
that you are seeing the received signal.  Some rigs have the equivalent
of IF1, and fewer have the equivalent of IF2.  The IF2 type of function
can actually be any IF.

It would be possible to locate a suitable place to sample the 8.83MHz IF
inside the 430S.  However, the location to pick off this signal must be
chosen carefully to avoid disturbing the signal in the IF.  You need to
avoid "loading down" the signal, or de-tuning the IF stage, both of
which are highly possible if your "tap" point is improperly chosen.  I
don't have a 430S schematic here, so I can't comment on whether the
point you've chosen would be OK or not.  Ideally, you want to tap off
from a low-impedance point, like the output of an IF amplifier, if
possible.  To get the equivalent of IF1, the tap needs to be before the
8.83 IF filter, and to get the equivalent of IF2, you need to tap off
after the 8.83MHz IF filter.

Hope this helps!

73,
Alan W2AEW

rb wrote:
> 
> Now that I know BS 8 modules for changing the SM 220 to a panadapter are
> available, I'm thinking about how to use it with my TS 430S.  The Kenwoods
> that are listed as being usable with either the BS 5 or BS 8 (depends on
> IFs) are the following:
> 
> TS 830 / TS 180 / TS 520 / TS 530 / 820 (no TS in front of the 820; should
> there be?)
> 
> The TS 430S has the 8.83mhz IF that the BS 8 utilizes.
> 
> It may be that the ones in the list have IF outputs for the task at hand,
> whereas the TS 430 definitely does not.
> 
> Also, the hookup diagrams in the SM 220 manual show an IF1 and IF2
> connection to the SM 220 with BS 5 or BS 8 module installed, from the rigs.
> One is bound to be the 8.83mhz signal (on those that have the 8.83mhz  IFs).
> The 8.83mhz output is labelled IF1, and the IF2 on the rig goes to V input
> (on the scope).  Don't know where it comes from inside the rig.
> 
> Looks like I would take out a connection from L4 in the 48 1370 00 IF board
> for the 8.83mhz IF1 signal.  Where would the other one come from for V input
> on the scope?
> 
> Obviously I don't know much about this, and may be confused in my ramblings.
> Would appreciate getting straightened out.  Maybe someone out there has done
> this exact mod and will enlighten me as to what needs to be done.
> 
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-- 
Alan Wolke, W2AEW
"i usta cuDn't speL enjinere, noW i ar wuN"