Jim, I agree. Advertising dollars is the reason. We have the same problem
with both of our German language magazines over here. I had one of the
testers for CQDL magazine tell me on the phone that if they find a problem
with a radio, all they can do is try to say it between the lines, but it is
better to not say anything at all.
HOWEVER, RSGB's RadCom magazine does indeed point out problems with
transmitter IMD and transmitter broadband noise. Peter Dodd does it kind of
softly with a careful choice of wording but clearly states it. In the last
couple of months he has tested the FT-1200 and FTdx3000 and dinged both for
broadband noise.
Rob has been focusing mostly on RX specs plus IMD for the TX.
I have been trying to nudge him into testing more things with the TX. The
IMD is clearly the biggest problem, but to those who run multi-multi (or
multi-TX field days stations), broadband noise is an even bigger problem.
Hey, how about this...
Back in the days of the cold war, all those east-block jammers would have
needed is a Yaesu FT-450D and an Ameritron ALS-500. A wonderful $1500
broadband jamming station! ;-)
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Jim Brown
Sent: Thursday, April 24, 2014 4:50 AM
To: tentec@contesting.com
Subject: Re: [TenTec] OT: Rob Sherwood's impression of the FLEX 6x00
Bob,
I rarely quote an entire email, but your post says so many important things,
and says them so well, that I want to emphasize them.
I have an Elecraft P3, which is a very nice, calibrated spectrum analyzer,
looking at the IF on both of my K3s. I often see signals that are so broad
that they are in violation of FCC Rules for spurious emissions by a wide
margin. I've also got an HP spectrum analyzer.
IMO, it is advertising dollars that cause ARRL to ignore this in their
product testing, and I think it's long past time that we call them on it.
I'd guess that more than half of the rigs they have tested fail to meet FCC
Rules when driving power amp.
73, Jim K9YC
On 4/23/2014 4:55 PM, Bob McGraw - K4TAX wrote:
> I too found that I got great audio or great signal reports with one of
> my radios. Those glowing audio reports are "on frequency"
> reports. I looked at the real output of a radio on my desk and saw
> all the crap being generated and transmitted some 20 kHz to 30 kHz
> away. I find it is the "off frequency" thus adjacent noise and IMD
> products that create a lot of unnecessary noise and pollution on the
> bands. And as users, it is difficult to find the source in many
> cases. For normal operation I use a spectrum analyzer connected to
> the receiver bandpass filter. With that configuration one can see
> much of the noise being generated as a certain signal appears and
> disappears thus correlating the noise change.
>
> As and example, look at the numbers. Take a given strong signal that
> is S-9 + 20 dB at your receiver. Then presume his IMD products are
> only 35 dB down. That then says his IMD products are equivalent to a
> S-6 signal. I realize that in many cases our local noise level is
> S-6 but be assured, that stations presumable IMD products contribute
> to the local noise level as well.
>
> I own one current production and very popular brand/model radio. When
> this radio is in transmit the noise on all HF bands increase 10 dB to
> 20 dB. That's right, transmit on 160M and the noise on 10M increases
> 10 dB. Put it in a Field Day environment and you'll likely learn some
> new vocabulary words from other operators. Put that radio on the same
> band as another radio and when it is transmitting the other radio on
> the same band is totally deaf.
>
> Yes, it is time to start a clean up of our spectrum. Unfortunately,
> many of the older radios are major contributors and even some of the
> new current technology ones aren't much if any better. And then
> there's the operator issues, taking a marginally spectrally clean
> radio and adding 10 dB to 12 dB of gain via a linear amp that may not
> be tuned correctly thus amplifying and generating more pollution.
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