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. > > > > > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
