[Amps] hotswitching 30s1

[Jim Thomson]

Date: Sun, 21 Feb 2010 08:16:28 -0800
From: "Mike" <noddy1211 at sbcglobal.net>
Subject: Re: [Amps] Hotswitching issues 30s-1



Key the amplifier and send the PTT signal from it to the transceiver!!!
Alex 4Z5KS 

##  IF you key the amps relays 1st....THEN send a signal back to the xcvr's
PTT input, what happens is you have now truncated the 1st 2-18 msecs,
or what ever the amps T/R relay's operate time is. 






How about using one of the simple Heil Foot switches, it has two switches
and keys the Amp slightly before rig. 

This would be the simplest way to address your problem.

###  great, but now you are stuck on PTT/footswitch mode. The simple
opto isolator method will eliminate the 15 msec mech spst relay in the
MK-V. As other's have noted,on CW mode only, the yaesu has  the adjustable
0-30 msec  digital delay [buffer] and no dits and dah's  get truncated. [Gives
the T/R relay in the amp a 0-30 msec head start].

##  the heil footswitch is an excellent footswitch though.  With a conventional
footswitch /ptt... IF u start talking b4 u hit the footswitch,  you will have RF 
coming out of the xcvr, b4  relay's in the amp operate. 

##  to get around that problem on the yaesu's.. on ssb mode,  we used an external
9-12 msec delay circuit, that inhibits the  yaesu's built in TX inhibit lead. With that setup,
you trip the vox, the opto keys the amp, then after the 9-12 msec outboard delay, the
yaesu TX inhibit lead is switched, and RF now flows from the xcvr.  Problem solved.

##  This external 9-15 msec delay is not required, IF the T/R relay's in the amp are
fast.. like sped up vac relays. [1.8 msec]   In our case,  we were using slow vac relays
[RJ2-B]  which have a 18 msec op time.   Even when we tried to speed the RJ2-B up, it's
still only  9 msec operate time. 

## The TX ibhibit lead function on the 1000-D  and  MK-V  are slick,  but both operate
differently.  The 1000/D  requires a simple grnd to ENABLE the TX inhibit lead. [ grnd
on TX].    The MK-V  requires   +12 vdc  to enable it's tx inhibit lead. 

## in the case of the 1000/D.... the opto keys the amp,  and the spst mech yaesu relay
[after 15 msecs]  applies a solid grnd to the TX inhibit lead, THEN  RF  flows from the xcvr! 
This works good on SSB, BUT will truncate the 1st 15 msec's  on CW.

later... Jim  VE7RF


Mike, K6BR