From: Rik Strobbe <rik.strobbe@kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Thread-Topic: LF: RE: FW: Icom Transceiver Question
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Date: Sat, 6 Oct 2018 08:24:57 +0000
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Subject: Re: LF: RE: FW: Icom Transceiver Question
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Hi John, Nicolas, Chris,

thanks for your respnses, I forwarded it all to N0DZQ.

73, Rik  ON7YD - OR7T
________________________________________
Van: owner-rsgb_lf_group@blacksheep.org <owner-rsgb_lf_group@blacksheep.org> namens John Langridge <kb5njd@gmail.com>
Verzonden: vrijdag 5 oktober 2018 22:18
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: RE: FW: Icom Transceiver Question

> Hello Rik , I don’t know the IC-718 but my IC-735 was modified for MF band
> with 45W out.


I guess the question is whether the IC-735 mod Nicolas refers to is
the MARS/CAP mod or the Jacek mod
(http://alain.st.free.fr/site1/aspicsite/IC-735/500KHZ/735-630m-mod.pdf),
the latter being reported to be pretty good.  Of course this does not
address the IC 718 question but I suspect the  MARS and CAP mod is
what is being described...

The problem with the MARS and CAP mod is many don't realize or
understand that the power being generated on 137 and 472 is harmonic-
rich and requires an outboard LPF and some other means of
amplification.  The outboard LPF is a new concept for some since that
functionality is being handled inside the transceiver for HF...

I've seen some report 40-50 watts of power output on 472, which is
harmonic-rich,  from a modified transceiver, believing that all of it
is on 472.  Sometimes they can be convinced to use an external filter
which lowers the power considerably.  I heard of one guy that didn't
like the fact that the filter "lowered" his power output at the
desired frequency so he removed it which, of course, is very
problematic, but it was the filter doing it's job.  Antenna matching
networks alone are typically very substandard and under-performing
when it comes to filtering functions...

It's probably not a good idea to do the MARS and CAP mods for 137 or
472.  I don't know for certain, but for a 718, that's probably the
only option (assuming it is an option anymore) without considerable
effort (like the Jacek mod).

73!

John