[Elecraft] Re: 2 K2s

[zl1aih@ihug.co.nz]

Hi All,
I've had several off-list requests for more info/circuit diagrams for SO2R 
using two K2s, and when I finish the project and test it thoroughly, I'll post the 
results to the reflector.
For those who would like to practice the technique, have a look at W4AN's 
audio switch-box circuit on OK1RR's DX and Contesting page, which leads 
you to N6TR's Two Radio Single-Op presentation - 1997 Dayton 
Hamvention.
A simple 2-pole 3 position switch, 2 mono and one stereo socket - easy 
wiring in a small box - one mono cable to your K2 headphone or speaker 
socket, the other mono cable to your other receiver (an old 520, whatever ) 
and the stereo socket to your stereo headphones.
Switch to your left - both ears on the K2, TX enabled.
Switch to centre - left ear on the K2, right ear on the other receiver, TX 
disabled.
Switch to right - both ears on the other receiver, TX still disabled.
You can practice during a rag-chew QSO - just switch to centre and tune 
around with your 2nd receiver while listening to the station you are working.
It's not difficult - when you think about the "cocktail party" mode, when you've 
been able to listen to at least two conversations simultaneously, sometimes 
the gist of three.
When it's your turn to transmit, switch to left and continue as normal.
I protect the 2nd receiver antenna input with a shorting relay, and a spare 
antenna - even if you're staying with the barefoot K2.

My first use of SO2receiver technique was in 1953, not contesting, but as a 
junior radio op on a passenger ship - coast station traffic lists were scheduled 
every 2 hours, on the hour or on the half-hour, and on the UK to NZ run, 
(about 32 days via the Panama Canal) we copied lists from GKL, DAN, PCH, 
WCC, KPH, KFS etc. etc., and several of these lists coincided - an 
experienced op showed me how to use two receivers, crossing the 
headphone bands over my head (primitive stereo?) and write the traffic lists 
in two columns in the official log, made easier because the coast stations 
sent each ship's callsign twice.  ( That same experienced op could do it 
without headphones, but he'd had more cocktail party practice than I.   
Passenger ships were like that in those days.)
Apologies if this post is directed towards the contesters on the list, but they'll 
just build more K2s <G>
More to follow, when I get it sorted.   This might take a while - I need to build 
the 2nd K2.  
73 Ken ZL1AIH