[CQ-Contest] PTT inhibit

Tom W8JI w8ji at w8ji.com
Mon Feb 20 12:43:10 PST 2012

With the Winkeyer, you can use the PTT lines.

MFJ makes a CW keyer, the 495, than can be manually keyed and has 
programmable keying delay.

DX Engineering has a sequencer that passes through PTT lines or CW with 

The Winkeyer I had nothing to do with. The last two, I designed specifically 
for radios that do not include a delay.

This all makes wiring complicated compared to the radio doing delay. A 
better hope is that Elecraft changes firmware for the delay, because it 
really is a good idea to have adjustable TX delay or inhibit that does not 
alter the CW.

My antenna switch controllers are Ameritron RCS12, which lock off the 
amplifier for pre-programmed times, and have internal band decoders to 
prevent picking the wrong antenna. This prevents operators from damaging 

----- Original Message ----- 
From: "Igor Sokolov" <ua9cdc at gmail.com>
To: "Tom W8JI" <w8ji at w8ji.com>; <sawyered at earthlink.net>; 
<cq-contest at contesting.com>
Sent: Monday, February 20, 2012 3:08 PM
Subject: Re: [CQ-Contest] How close is too close?

> Tom,
> I recently ran into the same problem with not enough TX delay of K3 in PTT 
> mode to use some PA and stack external switching. I wonder what work 
> around do you use. Since external sequencer and total rewiring is not an 
> option for my purposes (DXpedition), I plan to build additional delay into 
> DB15 connector body using KEY OUT and INHIBIT signals  available in the 
> AUX connector of K3.
> Does it sound like a good work around?
> 73, Igor UA9CDC
>> The K3 is not without flaw either. It would be nicer if it could be made
>> softer, and have ability to have TX delay without is chopping up the
>> characters. The lack of being able to add TX delay was giving me fits 
>> with
>> rising edge clicks from external switching times, until I added an 
>> external
>> sequencer. It took major hardware and wiring changes to work around the 
>> lack
>> of being able to just slightly increase TX delay.
>> I think 1 kHz is a good target spacing, unless the rigs are better. Then 
>> 500
>> Hz is probably a minimum for most rigs. It should not be that way, but 
>> that
>> is how it is. The lower the RX noise floor, the worse the transmitter
>> problem becomes. I imagine a MP sounds OK with S7 or louder background
>> noise.
>> 73 Tom
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