[Elecraft] K3 and amplifiers such as ALS-600

[Phil & Debbie Salas]

"Is it best to use a buffer send/ptt device like the Ameritron ARB-704 with
the K3?"

Not necessary.  The ALS-600 keying input has an open circuit voltage of 
12VDC, and requires you to sink 100ma (or 70ma with the QSK mod) to key the 
amp.  Easily handled by the K3 amp-key RCA output.

If you have a new ALS-600, ALS-500 or ALS-1300 with the ARI-500 for 
auto-band switching, the K3 band data output works great.  You do need the 
K3 TTL band data mod if you have an early K3 as the ARI-500 does not have 
pull-up resistors.

The K3 TTL band data mod is also required for the THP HL-1.5 amp, but not 
for the HL-2.5 (the HL-2.5 has internal pull-up resistors).  As I recall, 
the SPE EXPERT amp has internal pull-up resistors as well - but I'm not 100% 
certain about this.

Phil - AD5X