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[CQ-Contest] Multi-Transmitter Operation (Was about IC-7610)

To: cq-contest@contesting.com
Subject: [CQ-Contest] Multi-Transmitter Operation (Was about IC-7610)
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: k9yc@arrl.net
Date: Thu, 22 Mar 2018 09:59:17 -0700
List-post: <mailto:cq-contest@contesting.com>
LOTS of truth here.  There are two applications notes on my website, two about stubs for harmonic suppression (one is text, the other a Power Point), another about bonding, that are also required reading.  The one about bonding was the jumping off point for Ward's book, and the one about stubs offers important insights that George missed.

http://k9yc.com/LocatingStubs.pdf
http://k9yc.com/StubPlacement.pdf
http://k9yc.com/GroundingAndAudio.pdf

Another issue that W3LPL reminded us of is Passive Intermod which can be both inside and outside our stations. One common place it occurs is at the junction of the boom and mast via the rotator, and is solved by bonding around the rotator.  It also happens in electronics of all sorts, most notably switch-mode power supplies. If the harmonics/spurs you hear are "growley" sounding, it's probably passive intermod.

73, Jim K9YC

On 3/21/2018 7:15 PM, Tim Duffy wrote:
As AC0C points out - making multiple stations work is not easy. Bonding is
important (much more than most station owners realize) and using high
performance filters and quality interconnect cables (with good quality
properly installed connectors) is mandatory. Connectors MUST be tight. The
recent N0AX book on grounding and bonding is a good read on this subject.

What was a state of the art station design 20 years ago will not cut it with
the high performance SDR RX platforms of today. The epic W2VJN book is a
MUST read for anyone wanting to make SO2R or multiple stations at a single
QTH work properly.

Bottom line - there is no free lunch.


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