[Amps] ft-2000 vs pgxl

[jim.thom jim.thom@telus.net]

Date: Fri, 3 Sep 2021 10:31:45 -0400
From: <k1ttt.dave at gmail.com>
To: <yaesu at contesting.com>,     <amps at contesting.com>
Subject: [Amps] ft-2000 vs pgxl


<Just had to send pgxl back for replacement of an ldmos.  They say one
<possible cause of ldmos failure is not allowing for at least 20msec between
<ptt and rf, which I thought I had set. but maybe not when looking at it in
<detail. generating ptt through winkeyer which has settings at either 30 or
<50msec from n1mm logger so that 'should' cover modes where n1mm or the
<winkeyer generates ptt I hope.  But what about ssb vox?  Is there some
<setting I can't find to delay rf there?  Or will that always be longer
<because of dsp and af-if-rf chain??


<The pgxl provides for ptt-in and a ptt-out that isn't asserted until it is
<ready for rf, that should add safety to all modes except using ssb vox
<unless there is a way to interrupt the vox to ptt internal conversion in
the
<ft-2000. has anyone found a way to do that??

<Does anyone make a device to measure ptt to rf delay time?  I know I can do
<it with a 2 channel scope using an rf tap. but it would seem like a nice
<simple device to take ptt and rf, pass them through samplers and measure
the
<delay from ptt to the rf envelope start.

<David Robbins K1TTT

##  In the  ARRL extended lab report for my FT-1000MP-MK-V, they stated the
xcvr  puts out  1/2  power after  10 msecs on SSB mode.   They test by
applying a constant tone to the mic jack, then activate the PTT.    I
assume they test with the xcvr running rated  200 w pep out.   Then a 2
channel scope.  IE:  100 watts pep..after 10 msecs.   And I also assumed
say  50 watts after 10 msecs..if  xcvr dialed down to  100 w pep out  etc,
etc.

##  The  MK-V  has  a 0-30 msec  digital delay  for amps with slow
relays.... BUT that ONLY works on   CW mode.   I only use the internal
keyer.   On  SSB,  I don't want  ANY  RF coming out of the xcvr,  until the
relays in the  amp have finished their closure...including contact bounce.

##  My fix  for  SSB  VOX  was to use an external  20 msec delay...and also
use the handy dandy...TX inhibit lead on the din connector on the yaesu.
 On the   mk-V, the  TX inhibit lead requires  12 vdc..through a resistor
to enable the TX inhibit.    On my  yaesu  FT-1000D, there is NO   0-30
msec delay for  CW, so I have the problem on  cw as well as  SSB.   On the
1000-D, for the external  TX inhibit delay, I used the internal  1000-D
small relay that is used to key an amp.   I don't use that relay to  key
the amp.  Instead I use the electronic ground  in the 1000-D  to key an
external opto isolator..that keys the amp. That un -used relay now gets
re-used to provide for a ground on the 1000-D's  TX  inhibit lead.

The 1000-D's  TX inhibit lead  wants to see a ground.   The  re-used relay
in the 1000-D takes  15 msecs to operate.   The same relay in the  MK-V
only takes  5 msecs to operate, hence the use of an outboard  electronic
20 msec  TX inhibit  setup...for the  VOX  SSB issue.

I would have thought the    PGXL used  PIN diodes  or at least a vac relay
for TR  switching.   PIN diodes are stupid fast..and most vac relay setups
will switch in 1 msec.   But the yaesu xcvrs may well be putting out  XXX
pep out within 1 msec, on  VOX  SSB..and enough output to hotswitch the
relay setup in the  PGXL.

I noticed on the  SPE SS  amps, they have 2 x TX inhibit  jacks on their
rear aprons.   The older xcvrs  required a grnd for the TX inhibit lead,
the newer  xcvrs  require  12 vdc, and the spe does both...so  SPE
provides for the all important  TX inhibit delay.

My above scheme  works good since 2005,  but  only if the xcvr has the TX
inhibit feature available.    You could also  use the yaesu internal spst
mech relay ( 5 msecs)  to key an external spst mech relay..say 15 msecs..to
provide for a  20 msec  delay for the TX inhibit.

Jim  VE7RF