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.
73
Bob, K4TAX
----- Original Message -----
From: "Carl Moreschi" <n4py3@earthlink.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Wednesday, April 23, 2014 5:08 PM
Subject: Re: [TenTec] OT: Rob Sherwood's impression of the FLEX 6x00
I get nothing but unsolicited glowing audio reports on my Flex 6500. And in
the simple test I did comparing transmit noise generated on a band, it was
at least 30 db less than my Omni VII.
Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com
On 4/23/2014 5:45 PM, Bob McGraw - K4TAX wrote:
Yes, and it looks to me that some of the IM measurements do not meet
current FCC requirements. I wonder who and how the certification
measurements were conducted.
Of course I'm sure these aren't the only certification values that were
pushed through so the product could be sold. It seems that companies do
that these days more frequently than not.
I agree, we do need vast improvements with products on the air today. I
could imagine a situation much like pollution testing for vehicles. It
is up to the manufacturer to design it to meet specs and up to the user
to keep it in that condition. Unless grandfathered in, that would
obsolete a lot of radios unless the user modified them to meet specs.
And that in most instances would be next to impossible.
73
Bob, K4TAX
----- Original Message ----- From: "Rick - DJ0IP / NJ0IP" <Rick@DJ0IP.de>
To: <k9yc@arrl.net>; "'Discussion of Ten-Tec Equipment'"
<tentec@contesting.com>
Sent: Wednesday, April 23, 2014 3:30 PM
Subject: Re: [TenTec] OT: Rob Sherwood's impression of the FLEX 6x00
Jim, it is nasty compared to a Collins 32S3 transmitter and to radios
with
50v transistors, but compared to most radios shipping today with 12v
transistors, it seems to be average.
Which is why I have been saying for a long time that we need to start
SCREAMING at the OEMs to clean up their act!
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Jim
Brown
Sent: Wednesday, April 23, 2014 10:15 PM
To: tentec@contesting.com
Subject: Re: [TenTec] OT: Rob Sherwood's impression of the FLEX 6x00
On 4/23/2014 7:43 AM, Rick - DJ0IP / NJ0IP wrote:
I have just uploaded Rob's report of his experience using the newest
FLEX Radio to my web site.
VERY nasty IM -- run this thing into an amp and you're going to make a
lot
of enemies!
73, Jim K9YC
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