[TenTec] re Orion II curiosity

["Rob Atkinson, K5UJ" <k5uj@hotmail.com>]

There can be more than one cause of low p.o. if in fact it is really low.

as others have mentioned the first thing you need to do is have a way to 
measure peak power.  you need to get either a true peak reading meter (uses 
some kind of dc source, usually a battery or a wall adapter) or use an 
oscilloscope with the trace slowed down enough to catch the peaks.  Since a 
good peak wattmeter is about as much as a good used oscilloscope you may as 
well get a scope if you don't have either since you can do more with it.  
you can get a good deal on a tek 465 from http://www.testequipmentdepot.com
one possibility is that your orion is just folding back from a high vswr 
into either an antenna or amp.

another cause of low power out is agressive AGC response.   It's a little 
known fact that some rigs (all mfrs. not just ten tec) are sensitive to rf 
coming back to the rig; this affects the agc circuits in some way to provoke 
a response that causes the rig to do a false positive and limit p.o. below 
its spec'ed peak.   I say little known because, if a ham has a rig at a 
location where there is plenty of room for antennas as opposed to a ham on a 
small lot with the feedpoint right overhead, he may not notice anything 
amiss.

I'm not an engineer and don't pretend to be one; all I can say is that I 
have had big AGC responses with rigs, limiting power out and there was 
nothing wrong with the way the rig was adjusted or aligned, I simply had to 
take a number of measures to limit returned common mode rf (line isolators, 
ferrite chokes on mic and key lines, even removing the ground strap in some 
cases) but after doing that, the AGC response calmed down and the rig 
behaved as advertized.

I have a theory that manufacturers measure performance and test out rigs in 
nice ideal condtions--maybe the rig is on a bench with an antenna on a tower 
a few hundred feet away--
and everything seems to operate okay on air so they don't bother with a few 
ferrite beads and shunt caps in choice spots inside, then joe ham gets the 
rig and, with a dipole hanging right outside overhead, has these mysterious 
problems.

it's a little bit harder to measure or view your AGC response since you have 
a single led that flashes as opposed to a meter, but if your Orion is not 
too far away from your antenna(s) and/or (especially) if you have reports of 
tx audio distortion which may only be on amplitude peaks you may very well 
be experiencing excessive AGC resulting from rf feedback.

In any event, you paid for a 100 watt rig; not a 50 or 70 watt rig so you 
are entitled to get what you paid for.  Should you verify that it is indeed 
not putting out 100 w. pep, I hope this helps you solve the problem.

73,
rob / k5uj

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