--- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...>
wrote:
Hi Jim,
I prefer that my GG amps cannot run in too high dissipation at
full
drive. They should have no problem when the antenna gets lost...
73
Peter
### Peter, et all
### I had an engineer buddy of mine cook up a high reflected
power shut down circuit for me. My buddy got a hold of a
ton of Bird single line sections. He joined two of em
together with some brass rod and soldered the outside flanges...
to fabricate a "double line section".
### He made two such assemblies. We installed one on the
input of the amp... and the 2nd one on the output. [4 x slugs
installed]
### Since the big amp is remoted 30' away from the shack.....
we had to be able to read all 4 x line sections in BOTH
locations. My engineer buddy designed a peak reading board that
would work with all 4 x line sections.... and continuously
monitor the PEP reflected power from the ant [line section # 4 ]
### Only one bird 30 ua meter is used in each location.... and
either end can be switched independently to any of the 4 x
line sections. He used line drivers at the amp end.. to drive
the box in the shack.
### The high PEP reflected power threshold is fully
adjustable... and in this case was set to 1 kw. When the
threshold is exceeded.... a minature dpdt relay operates [ in <2
msecs] and one set of contacts applies -10 vdc to the ALC
jack of the Yaesu MK-V.... shutting it down asap !!
### The 2nd set of conatcts activates a 2nd, identical relay
[also in < 2 msecs]
### This 2nd DPDT relay opens up the key line to both the IPA
[ intermediate pwr amp] and also the 12 kw amp. The
circuit latches.... and lights a red led. A spring loaded
push button resets the circuit . [AFTER you find out why the
high swr condition occured]
### Since the 2 x minature relay's are sequenced.... the ALC
shut down on the xcvr occurs 1st.... followed by kicking BOTH
amps off line ! NO Hot switching!
### To key both amps.... I used a PAIR of P+B opto
isolators.... they run on +13.8 vdc @ 10 ma each.
The "electronic TX ground" from pin 2 of the MK-V's band
data jack supplies the grnd to both opto's on TX.
### The output side of each opto is rated at 200 Vdc @ 1 A
CCS. They also have 4 kv isolation between input and output...
and operate in under 100 microseconds. Cheap too.
### We used +120 vdc to operate all 4 x vac relays in the big
amp. [speed up circuit, with a pair of dropping resistors]
### The high swr circuit could have been configured to open
off the INPUT to both opto's instead.. of the Opto outputs. Moot
point.
## I had my engineer buddy also include a short 12-14 msec
delay... used in conjunction with the yaesu "TX inhibit lead"
[used on both the 1000-D... plane MP.... MK-V /field.
## BOTH amps are keyed NOW.... after 10-14 msecs... TX
inhibit is removed... allowing full power from the Yaesu MK-V.
### This delay ensures the vac relays won't hotswitch on TX...
even though all 4 x are sped up.... we are using RJ1A's on the
input side [one for drive RF... the 2nd RJ1A shorts out the
100k resistor to remove the cutoff bias. We paralled a pair
of larger, slower vac relays on the output 10 kw side.
### We didn't want a situation where input relays operated
1st... drive applied to cathode... and no ant connected ...yet !!
### This delay circuit is for SSB / FM /AM
### In the MK-V menu.... on CW only.,... you can delay the RF
by 0-30 msecs [ digital delay... NOTHING gets truncated
either] ... and still key the amps in real time... NOW. It
needs to be set between 10-30 msecs.
## The above T/R scheme is super fast vox cw/ ssb /fm /am.
Due to the 'slower' larger vac relays on the 12 kw output
side....qsk is not recomended.
### If anybody is interested.... the high swr circuit will be
made available down the road... along with the rest of the
schematics. It's saved everyones bacon a few times so far...
works slick... and works on any bird line section / slug size.
Later......... Jim VE7RF
