[Elecraft] Sequencer keying with K3/XV-144 without rigblaster?

[Brian Alsop]

I guess I'm missing the boat on this discussion.  

I thought all high power VHF ops used an external sequencer board that 
did the following type of thing.
RX to xmit:
1) Bypass the mast mounted preamp, wait a bit
2) Put the amp in the tx mode, wait a bit
3) Put the xvtr in the tx mode, wait a bit
4) inhibit the RF output from the rig until 1-3 are complete.

With a relay based system 1-3 could easily be 60ms or more.

Going to receive does a similar thing --i.e. unkeying the various 
components with delays..

You're not going to get his set of multiple delays from the K3.

There are external sequencer boards available as kits for about $20.  
The K3 has an inhibit line for such use.

And yes, the big guns do have difficulty in the bang-bang contest 
mode.   You call them once and occasionally get the comment,  I'm not 
getting your call, my sequencing hasn't completed.

73 de Brian/K3KO



D6XY wrote:

>
>W7GJ, Lance wrote:
>  
>
>>Unless I am totally missing the boat here (which certainly happens), it
>>seems to 
>>me that the cleanest way to make the K3 flexible enough to replace
>>existing 
>>equipment requiring external sequencers, would be to be able to adjust the
>>time 
>>between K3 PTT keying and the KEY OUT jack and/or KEYOUT-LP pin (or some
>>other 
>>available pin) closure between standard short delay (20 ms) or a long
>>delay (for 
>>example, selectable between .2, .4, .6, .8 or 1 second). 
>>
>>
>>    
>>
>
>I don't think you are missing the boat but you are likely to miss DX if it
>really takes as much as a second to switch from TX to RX. By that time
>someone else will have got there first.
>
>I had a discussion with Elecraft about this when the feature was being
>enabled, I did some research on the maximum switching time of large VHF
>relays and came to a figure of 50mS. Unfortunately Elecraft could not mange
>such a long delay at the time in that version of the firmware.
>
>For long delays of VHF equipment I am not sure the K3 is the right place for
>a long delay as it is not something configurable by band and should there be
>a switching fault, the smoke will still emerge, just 1 second later than it
>would otherwise.
>
>If you are using the transverter output you might as well just put a delay
>relay or PIN diode in the TX line. No relay is going to object to hot
>switching 1mW. This switch should be controlled by the ready signal from the
>amplifier, or whatever it is that is taking so long to be ready. To avoid K3
>power errors you might need to ensure a good match. A simple alternative
>would be to switch the bias to the TX stages of the transverter instead.
>
>
>
>  
>