[CQ-Contest] ICOM 7610 & C31XR - the IC7610 experience

[Tim Duffy]

Hello Terry:

We used two Icom IC-7610s this past weekend at DR8A in Germany as our test
for our WRTC2018 setup. Using the Low Band Systems (LBS) triplex sharing
system for 20, 15 and 10 meters and high performance LBS filters for 40 and
80 meters. HamPlus antenna switching and sharing. Absolutely no trouble with
overload or half harmonics between the two IC-7610 radios running on a
single feedline OptiBeam tribander. Yes, that includes using the preamps on
15 and 10 meters. This well engineered system worked great.

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.

73,
Tim K3LR

-----Original Message-----

On 21-Mar-18 10:11 AM, Terry Zivney wrote:
> The C31XR should not be a problem
> However, the ICOM 7610 may be.
> I have used TenTec radios and more recently an FTDX5000MPwith closely
spaced monobanders (interleaved 10 & 15, for example)with no problems just
with stubs on low power and just Dunestar600s with high power.
> BUT, this past weekend at N1UR for RDXC. Ed had monobanders withadjacent
bands on separate towers. We had Dunestar 600s band passfilters. He had no
problem with his FT1000Mk5 Field but I hadproblems with the new Icom 7610. 
In particular, I needed thepreamp on 15 meters. But, that brought the
overload light on.When the ICOM 7610 goes into overload, things fall apart
prettyfast.  Also, you cannot use the DIGI-SEL to add some badly neededextra
front-end selectivity when you want to use the preamps.
> BTW, the 7610 (and undoubtedly other radios with the samearchitecture) has
a new type of second radio problem not foundin traditional superhet radios.
When listening on 3505 you willhear the second radio on 7010.  The 1/2
harmonic!  Again, Dunestarsin line.  This is apparently due to the
decimation process of theSDR.
> Good luck.
> Terry N4TZ
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