[ICOM] Split Frequency extra signals with IC-775DSP and IC-7800

[Adam Farson]

Hi Skip,

This is the well-known IC-775 PLL leak problem. When operating split with a
close offset, the "A" (receive) synthesiser output will leak into the signal
path from the "B" (transmit) synthesiser to the transmit mixer, about 30 to
40 dB below the "A" output. I believe that the converse is true on receive;
"B" will leak into the signal path from "A" PLL to the "A" first mixer.

Icom America has a fix for this problem. They fit both PLL units with
improved shielding. I would recommend you contact the Bellevue WA service
centre.

Cheers for now, 73,
Adam VA7OJ/AB4OJ


-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
Behalf Of Skip Cameron
Sent: 16 February 2006 23:20
To: icom at mailman.qth.net
Subject: [ICOM] Split Frequency extra signals with IC-775DSP and IC-7800

I ran some tests using split mode on CW with my IC-776DSP and K5AB using his
IC-7800 We are about 20 miles apart.
If I used a 2 KHz split, K5AB can also hear my signal, about 40 db down, +2
and -2 khz from my transmit frequency. The primary signal was S9+40.
With K5AB using a 2 KHz split, I hear his signal about 40 db down -1 Khz
from his transmit frequency.

Without split mode set, we still heard the offset signals.

We are wondering if this is unique to Icom and is it receiver overload or a
transmitted signal?
Anyone have any knowledge of this?

Skip W5GAI



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