[TenTec] OT: Rob Sherwood's impression of the FLEX 6x00

Bob McGraw - K4TAX RMcGraw at Blomand.net
Wed Apr 23 19:55:19 EDT 2014


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 at earthlink.net>
To: "Discussion of Ten-Tec Equipment" <tentec at 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 at DJ0IP.de>
>> To: <k9yc at arrl.net>; "'Discussion of Ten-Tec Equipment'"
>> <tentec at 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 at contesting.com] On Behalf Of Jim
>>> Brown
>>> Sent: Wednesday, April 23, 2014 10:15 PM
>>> To: tentec at 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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>>
>>
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