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
Tim, 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

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