Topband: Rig Comparisons

[David Harmon]

Yep.....I think the YAKITT outfits are all suffering from the
'notinventedhere' syndrome.
There is plenty of it out there....especially in offshore mfgrs.


73

David Harmon
K6XYZ
Sperry, OK

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Jim Brown
Sent: Saturday, August 2, 2014 11:32 AM
To: 'TopBand'
Subject: Re: Topband: Rig Comparisons

On 8/2/2014 9:06 AM, Michael St. Angelo wrote:
> Jim,
>
> The Mobility industry has been using pre-distortion. It has finally 
> been implemented in the Hermes and Apache Labs Transceivers by Warren C.
Pratt.
> He has won the ARRL Technical Innovation award and justly deserves it:

Interesting technique. The late Richard C. Heyser, who worked at JPL in
communications, predicted exactly this around 1980 to compensate for
non-linearities in audio systems, which are much more varied and complex. At
least a half dozen pro audio companies were doing things like this nearly 30
years ago with power amplifiers for studio monitors, and as far back as the
'70s, several manufacturers sensed distortion in loudspeakers and used
motional feedback to correct it. Good to see ham radio catching up.

Looking at the reference, the Hermes is the product of the TAPR ham research
group, and a building block for SDRs. Apache is a new manufacturer of SDRs.
The new Flex models are rumored to be much better than those reviewed by
ARRL. But SDRs are a tiny fraction of the ham world -- the K3 and KX3
probably being the most widely used.

How many decades do you think it will take this concept to get to Yaesu,
Kenwood, ICOM, and Ten Tec. How many years did it take Yaesu to fix their
awful clicks? And none of them have learned about "the Pin One Problem,"
published in the Journal of the AES in 1995 (by ex-W3WJE, SK), which is a
major cause of RF susceptibility (often called "RF in the shack").

73, Jim K9YC
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