I think I can understand what is happening here. The following applies if
the PIN5 switch is the built into the amplifier. If it is an external box,
some
things may be a little different operationally but the principles should be the
same.
The primary problem is DRIVING the amplifier while it:
A - Is turned on
B - Is in operate position [not standby] [Grant, does the AL1200 or if
external, PIN5 switch, have a OPR/STBY switch like the AL80A?]
C - Does not receive a keying signal.
If it sounds like I just stated the obvious, I probably did, but please bear
with
me.
"C" can happen regardless of wether one uses the keying loop or the QSK
output and really has nothing at all to do with the ORION or for that matter,
any other transceiver. It is a characteristic of the PIN5 switch installation.
Here is what I think is happening.
When the amplifier is turned off or if the OPR/STBY switch is in STBY
position, a relay inside the amplifier bypasses the amplifier completely and
the transceiver is directly connected to the antenna at all times. However;
when the amplifier is turned on and the OPR/STBY switch is in the OPR
position, the transfer relay in the amplifier inserts the PIN5 diode switch in
line and now we have a new situation.
In this case, normally, when the transceiver goes into transmit, either the
QSK or TX EN lines will key the PIN5 and all will be well with the amplifier.
BUT................if you are using the QSK line and for some reason the line
becomes disconnected, when you transmit, the transceiver develops power
but is delivering it to the receive diodes. Ameritron apparently anticipated
that by putting the fuse lamps in place. Over the years, that is always what
happened when I blew those things! :-)
So, first point, using the QSK output will not GUARANTEE that this willl not
happen.
If you are using the keying loop, and the keying line becomes
disconnected, the amplifier will not acknowledge the TX REQ and nothing
happens. But, if one forgets to turn the keying loop on and transmits, the
radio, good kid that it is, obeys and transmits into the rx diodes since it has
no reason to check the TX EN handshake in this case.
Second point, using the keying loop will not GUARANTEE that this will not
happen.
In Grant's case using the keying loop this what I think happened. As I
understand it Grant did not enable the keying loop feature.
And as mentioned above, the cable can become disconnected for any
number of reasons.
Any way you look at it there is a chance that one can transmit when one
should not through no fault of the ORION or any other radio other radio.
What to do? You could use the keying loop and just leave it enabled at all
times and select the amplifier via the OPR/STBY switch. But you still might
accidentally change the status of the keying loop at some time, or a
firmware upload my not preserve the keying loop status. Don't know about
that one.
Probably using the QSK line for keying and using the OPR/STBY switch on
the amplifier [or PIN5] for putting it on or off line will be the least likely
to
create a problem.... The only time a problem would occur in that case is if
the cable becomes disconnected and you can verify that connection by a
simple observation if the PIN5 is built into the amp. First, put the amp in
STBY. Key the rig. Any power level out will be OK because the amplifier is
bypassed at this point. If the meter pilot lamps dim a little bit, the keying
cable is in place. If the lamps do not dim, the cable is disconnected or
something else is not working.
Now about the diode mentioned in the Alpha note. Terry, W6RU, and I
have been having a fairly involved discussion off list about my statement
last evening that I did not see a need for the diode. I say here and now, it
IS needed in some cases if you use the keying loop and "Y" cable idea.
[which by the way, is about the only way to key a PIN5 switch with a
Paragon for sure and probably the Omni V and VI series. To my
knowledge, they do not have the QSK output. I know for sure the Paragon
does not.]
Terry called me on my statement and after working through several
scenarios, I see that in the case where the amplifier is turned off and using
the Y cable and keying loop, it is possible the the keying input circuit in the
amp will pull the TX EN low enough to actually key the transceiver. Not so
good. The isolation diode eliminates that possibility. In the case of my
PIN5, the diode is built in but that may not always be the case with other
equipment.
All that said, I have had very good luck with my AL80A/PIN5 over the years
and could not be happier once I discovered how to use it.
Enjoy that combo Grant............. :-)
73 de Lee, WA3FIY
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