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RE: [TenTec] SDR's, You and RFI - Real Long

To: <tentec@contesting.com>
Subject: RE: [TenTec] SDR's, You and RFI - Real Long
From: "RM" <royalct@inr.net>
Reply-to: tentec@contesting.com
Date: Sat, 11 Dec 2004 08:47:32 -0500
List-post: <mailto:tentec@contesting.com>
In general, a ham rig should not have RFI problems regardless of the
technology used.  PROVIDED YOU HAVE A GOOD RF GROUNDING SYSTEM..... I've
been involved in the design of military radios that must perform in harsh RF
environments (and even then they sometimes have RF problems).....don't think
ya'll want to pay that kind of cash for a ham rig.

The first time I used my Orion (and my two Icoms) I had RFI related
problems........Stupid me, didn't follow the instructions for wiring the
mike on the Orion (Yes, some times my discipline breaks down)............

I run about SSB 1000 watts peak and do not have RFI problems in my radio
room; equipment includes the Orion, IC757DSP, IC765, TNC, VHF/UHF,
Computers, computer modems, monitors, telephones and the list goes on.  When
I first moved into this house I had RF interference.  After I cleaned up my
RF grounding system, I no longer had RFI problems except when I do stupid
things like the microphone wiring above.

Yes, I expect my rigs to not have ANY RFI issues, but I can't afford those
rigs .  But I can afford to buy a rig with a lower level of RFI proofing and
do a little work to create an effective RF grounding system for my shack....
It's all trade offs of cost and performance.

N0KHQ recently posted a very good discussion of creating a RF ground system;
what he did is basically what I have done here.  I highly recommend that
ya'll reread his discussion.

Remember, I do not aware of any consumer radio that will properly work 100%
in a harsh RF environment (in my opinion that includes not having a proper
RF ground system).


Ron...NU1U

-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of jerome schatten
Sent: Friday, December 10, 2004 20:03
To: tentec@contesting.com
Subject: Re: [TenTec] SDR's, You and RFI - Real Long 

John:  Your fine work notwithstanding, this issue begs the question: Why
should SDR's be any more sensitive to RFI than any other radio that has
microprocessors, lsi chips, memory, dsp's, etc,. under the hood?  The answer
IMHO, is that they shouldn't.  More careful attention to the layout,
shielding, cabling and bypassing (good mechanical and electronic
construction techniques--hardly rocket science) would have produced a radio
that didn't have the RFI problem in the first place.

The answer: "..Welcome to the world of SDR's" doesn't address the problem at
the source, the design stage.  One should not have to rewire the
neighborhood to make a radio work properly.

My comments are not meant to diminish in any way the wise and valuable
suggestions you've made as regards grounding and RFI minimization -- my only
point is that it could have been done under the hood with less ruckus.  If
we except the 'inevitability' that SDR's will always be problematic
performers in high RF fields, we're voting for more of the same.

Best regards,
Jerome - VA7VV

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