[TenTec] Dirty Transmitters - Flex and Yaesu

[rick@dj0ip.de]

Guys, how about this for an interpretation of dirty TX:

I lived on a block with three hams.  We had a Ten-Tec, an Icom, and a
Kenwood, with about 100 meters between us.
The Ten-Tec and Icom both fed amps.  The Kenwood was run barefoot.

When the TT or ICOM were on other bands, they did not disturb either of the
other radios (on other bands).
When the Kenwood was on the air on any band, it raised the noise level by
several S-Units on the other two radios, regardless of what band they were
on.

I contend that "that" Kenwood model was a dirty transmitter.

All three met FCC IMD rules.

That was an older Kenwood and I can't recall the exact model number.
However many of today's brand new radios are just as bad in phase noise as
that radio was - even some that cost several thousand dollars.

I'm not talking about 3rd order IMD here that affect the band in use, I'm
talking about dirty PLLs and lack of low-cost filtering to clean them up -
which affect all bands if you live within a block or two of that TX.  Put an
amplifier behind it and then you RF-SPAM a mile or two.

What Kim was referring to (pre-distortion) may be state-of-the-art in
theory, but it is not readily available in a mature radio.
FLEX does not have it and who knows when.  And even then, at what price?

Anon has it but their software in general is not as ripe as that of FLEX.
I base this on Rob Sherwood's report earlier this year of trying to get an
Anon set up to run a contest together with his alpha amp.  He compared that
to doing same with a FLEX.  

Until a feature is available to us at an affordable price, I would not call
it state-of-the art feature, I would call it near-future feature.

I have never run a FLEX, nor an ANON and perhaps it is unfair for me to pass
judgment on them.
But I have been listening to what Rob Sherwood says since 1976 and so far he
has been spot on with his judgment.
Elecraft, FLEX, TEN-TEC and many other companies listen to his suggestions.
Those who don't work with him so closely are coincidently the ones whose
transmitters are polluting our bands!

Clearly Elecraft has shown us the path.
I hope others will follow and even use this technology in the lower cost
radios.

In any case I applaud everyone participating in this discussion.
It is high time we discuss this topic as a technical topic, rather than
blaming it on some LID ham.

Maybe some of the others should start their own group and reminisce on the
past.
I would probably join it.  I enjoy that too.  
But THIS group has always been one of the better discussion groups on the
web and topics like this are the reason why.

73 - Rick, DJ0IP
(Nr. Frankfurt, Germany)



-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Kim Elmore
Sent: Thursday, December 10, 2015 4:28 AM
To: tentec at contesting.com
Subject: Re: [TenTec] Dirty Transmitters - Flex and Yaesu

I'm not sure I understand the point of this. True "state of the art" can
become hideously expensive. Somewhere, there has to be some give.

Yes, some of the current and many of the past transmitters are absolute
dogs. But, they weren't state of the art even in their day. With SDR we can
introduce predistortion for SSB to minimize IMD. Phase noise has been a bane
since PLLs were introduced. I suppose that "state of the art" signal purity
could be crystals. If the rules are interpreted that way (unlikely), we
couldn't use any variable frequency source until its spectrum was as pure as
a good crystal oscillator. As for CW BW, that's been understood for quite a
while and ways to deal with it have been around a long time. Technically,
any transmitter that has a broad CW BW is in violation and subject to
sanction.  The list goes on for a while, e.g., RTTY BW.

I don't believe that the FCC ever intended to enforce true
"state-of-the-art" because very few can afford it. How much flexibility
should be allowed is a better question and that is inevitably converted to a
number somewhere by someone. Literal "state-of-the-art" is unattainable by
most.

Kim N5OP

On 12/9/2015 7:19 PM, Jim Brown wrote:
> On Wed,12/9/2015 4:34 PM, terry foskey via TenTec wrote:
>>   Jim,I am in engineering, questioning why and developing designs, 
>> it's what I do. I have commercial and Amateur licenses. The rule you 
>> provide for Ham operations is true, however, the passage can be 
>> interpreted many ways and I stand my statement there is no specific 
>> rule being violated.
>
> It is, but you're looking for a number. The rule is written so that 
> the "number" is dictated by the state of the art. It allows the Rules 
> to progress with developments in ham radio manufacturing. I serve on 
> an international standards committee, and we have written Standards in 
> exactly that way, and for that exact reason.
>
> Elecraft has set the state of the art with an expensive rig, Kenwood 
> has further defined it with a moderately priced rig. I would thus 
> define what Kenwood has done as "the state of the art" for the masses.

-- 

Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)

/"In theory there is no difference between theory and practice. But, in
practice, there is." //- Attributed to many people; it's so true that it
doesn't matter who said it./

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