[Elecraft] Fw: K2 Trouble / Problem

[George, W5YR]

Ron presents his usual thorough and incisive account of noise blanking in
general, as well as in the K2.

The only point that I would add in considering noise blankers is the
importance of the location of the blanking circuitry in the signal path of
the receiver.The shape and high-frequency components of the noise pulses
must be preserved for effective blanker operation. That means that a minimum
of bandwidth limiting should take place prior to the blanker.

In the K2, the blanker is placed immediately after the post-mixer amplifier
and prior to the IF filter. That is an example of "doing it right." There
are other receivers on the market that place the noise blanker further down
the chain of frequency conversions and filtering. These receivers are noted
for having relatively poor noise blanking capabilities.

As with most signal operations in our receivers, optimum results would be
obtained if they could take place virtually at the antenna terminals. But,
until we have a major reduction in costs and a major improvement in
capabilities, we must be content with our present down-conversion schemes to
reduce the signal frequency to the range where economically feasible
components and circuitry can be used.

The K2 remains a landmark case study of elegance in transceiver design. To
paraphrase Sir Winston Churchill, "Never before has so much performance been
owed to so few components."

73, George W5YR
Fairview, TX
w5yr@att.net
http://www.w5yr.com


----- Original Message ----- 
From: "Ron D'Eau Claire" <rondec@easystreet.com>
To: <Elecraft@mailman.qth.net>
Cc: "'W3EME Brian Manns'" <w3eme@mtwirefree.net>
Sent: Wednesday, March 24, 2004 10:14 AM
Subject: RE: [Elecraft] Fw: K2 Trouble / Problem


The K2 noise blanker words extremely well on the types of noise it is
intended to remove. It probably should be called a "high amplitude fast
rise-time noise blanker" for all of those who think that it should remove
ALL types of noise. It won't.

<snip>