EMRFD Message Archive 2212

Message Date From Subject
2212 2008-10-08 15:16:20 timshoppa K2 design impressions
I have had opportunities to use the K2 in the past couple of years,
and even seen the innards of one, but only today did I discover that
I could go to Electraft.com and download the manual with schematics.

Having spent some time homebrewing my own receiver, I am exquisitely
impressed with the brilliance of the K2's simple design. Many of the
same subcircuits they use are in the ARRL handbook or EMRFD with
small variations. But they have been combined with an incredible
economy to produce an all-HF-band multimode transceiver.

For example, my homebrew LO chain has a separate VCO oscillator for
each band. But the K2's designers are smart - they use a single VCO
with clever combinations of relays and fixed capacitors and
varactors to do the job. A simple AGC system keeps the VCO amplitude
constant through all the bandchanges. The result is a LO that covers
all the ham bands with fewer parts than my breadboarding, that
converts directly to the first and only IF (contrast with the
YaeKenIcomWoodSu multi-conversion transceivers).

Tim N3QE
2214 2008-10-08 19:23:31 bobtbobbo Re: K2 design impressions
2217 2008-10-09 08:01:58 cwfingertalker Re: K2 design impressions

Most QRP designs of the past are like that. Very simple yet very
effective. Hence the nomenclature Elegant.

It reminds me of the age old backpacking rule about choosing and
picking things you put in your pack. You count the ounces and the
pounds take care of themselves. TFRs (trail friendly radios) were
probably an extension of that backpack mentality or design philosophy.
A very simple elegant design coupled with very desirable results.

Bill N7EU