[Elecraft] Microphone for K2

[Jim Brown]

I must not have been clear. it is not "another option" -- it's precisely the 
Plantronics headset I noted I had seen at Fry's Electronics. So everything 
that applies to making a cell phone headset work applies equally to 
making the PC headset work.  

The point is that these headsets differ only in 1) the quality of the headset 
and mic elements; 2) Physical comfort; 3) the connector(s) on the end. All 
of the Plantronics headsets have noise cancelling mics. Bill, NY9H, has 
observed that these capsules (and the capsules used in the VERY 
expensive ham mics) sell for half a dollar or less without the name of the 
very expensive ham mic marketing company on them. 

Another point. Plantronics is an old line telecommunications company. 
The "Altec Lansing" NAME was purchased at least a decade ago, is 
applied to cheap junk from the far east, and sold. There is no connection 
(other than this sale of the name) between the company using the name 
and the company that MADE the name a household word for high quality 
audio. In spite of its pedigree, I'll bet your headset works a treat on the K2!  

What can be very tricky to get to work is a headset with an inline PTT 
switch sold to work with a ham talkie. In essence, you have to do major 
surgery on what is a very delicate (and cheap) switch with very tiny and 
delicate wiring to either disable it or rewire it to work with a radio for which 
it was not intended. I  bought one of these new at a hamfest. VERY bad 
idea. 

Jim Brown  K9YC

 --Original Message Text---
From: G3VVT at aol.com
Date: Wed, 1 Sep 2004 19:08:31 EDT

Another option may be to use a PC microphone/headset that are available in the market 
at very low prices. I use an Altec Lansing AHS-201 headset electret boom microphone 
with a single earpiece with my K2. As the headset is terminated in the standard 2 x 
3.5mm stereo jacks I made up the necessary connectors and a PTT in a small plastic 
box with two leads out for the K2,  8 pin mic connector and a 3.5mm stereo plug for the 
headphone connector. A foot switch could be added if desired for PTT. The +5V bias 
voltage is already available at P1 on the K2 Front Panel board. All it takes is a suitable 
resistor to provide the bias voltage needed from the +5V on P1 pin 6 to the designated 
AF pin or pin 1 on the K2/KSB2 side. There is already a 2.2uF isolating capacitor, C34 
on the KSB2 I/P, so no other isolation is required with the standard K2/KSB2. The bias 
voltage needed for the Altec Lansing AHS-201 does not seem critical. I used a single 
AA 1.5V dry cell in tests and with that was able to overdrive the K2 in the microphone 
high setting.
 
An added advantage with this particular headset is the microphone is noise cancelling 
for use in noisy situations and the earpiece seems to work well with the K2 giving a 
good RX audio level. I had built the setup originally to use with a Yaesu VHF/UHF 
mobile and it was pleasing to find that it worked very well with the K2. Trying it out was 
easy as I already used the Yaesu standard for the K2 8 pin microphone connector. The 
Altec Lansing AHS-201 should be retailed from about $10 in the USA. The obsolete 
AHS-15 should also work well at an even cheaper price if still available.
 
Bob, G3VVT
K2 #4168