[Elecraft] K3 -> Very Early Acom 2000A

[Dick Green WC1M]

Hi Will,

I have an early 2000A driven by a K3. I'm pretty sure you can just connect the Key Out jack on the K3 to the Key In jack on the 2000A, and the hard-coded transmit delay in the K3 (5ms?) will be adequate for the vacuum relay in the 2000A to switch. 

However, if you want to be 100% safe, or if you get key sequencing faults from the 2000A, you can use the 2000A key loop. This requires connecting the 2000A Key Out jack to the K3 TX INH pin (pin 7) on the Acc jack. Since the 2000A pulls Key Out low when it's OK to transmit, you need to pull pin 7 on the K3 ACC jack  up to 5VDC (max) with a 10K resistor. To do that, you'll have to run a line over to the K3 12VDC jack and use a resistor divider or a transistor circuit to drop it down to 5VDC (the latter is how I did it.)

I've seen a diagram where someone got the 5VDC pullup voltage by shorting pin 1 to pin 7 on the Acc jack. Pin 1 is the FSK input, which is pulled up to 5VDC. I don't know if this works, but it's simpler than what I described above. I'm pretty sure it means you can't use the FSK input.

Once you get the hardware connected, go into Config:TX INH and set INH = Hi. You'll need to be in tech mode to do this.
 
Hope this helps.

73. Dick WC1M


-----Original Message-----
From: William Liporace <wc2l at wc2l.com> 
Sent: Sunday, July 8, 2018 2:13 PM
To: Elecraft at mailman.qth.net
Subject: [Elecraft] K3 -> Very Early Acom 2000A

Hi Folks,
I am looking for instructions of tips on how to hook up the very early Acom 2000A amps to my K3. Any tips or tricks would be great!!

TNX Will WC2L

--
William Liporace WC2L
http://www.wc2l.com or http://dxc.wc2l.com AR-Cluster Node  telnet dxc.wc2l.com or 144.93 MHz wc2l at wc2l.com