Terry: All very interesting observations on the Orion! You mentioned that
the radio shuts down when the current reaches a certain level, which I have
seen my radio do on several occasions. Do you have any idea which circuit
sets the 'trip level' for that shutdown and is there any way to adjust it?
My guess is that it's something controlling the main power relay on the A0
board near the DC power connector.
From what I'm able to tell, the Orions have two ALC circuits: one is a
software derived system that also sets the audio for a very wide range of
input levels and operates the ALC light on the front panel, and the other is
a fairly standard hardware circuit. The hardware system only seems to
operate when the power is near the maximum set by the internal ALC level
control and there appears to be a "voting' circuit on the A5 board that
controls the power, based on which ALC is demanding power reduction. Unless
you are running near 100%, that will always be the software derived signal.
When the power is set below 100%, the SSB peaks bob around wildly, never
reaching the CW level, however when running 100%, the peaks stay 'nailed' at
100 Watts, as shown on my N8LP LP-100 Wattmeter.
That means that in order to drive a linear that requires 40 Watts of drive
and have both internal ALC's properly controlling peaks, you would need to
put a 4 dB attenuator on the output of the Orion and run it at 100 Watts, or
reset the ALC level for 40 Watts of output power. Neither seems like a
great prospect!
Ron N6IE
www.N6IE.com
----- Original Message -----
From: "Zivney, Terry L." <00tlzivney@bsu.edu>
To: <tentec@contesting.com>
Sent: Tuesday, February 09, 2010 7:22 AM
Subject: [TenTec] Orion ALC and power output indication meter and
speechprocessing
Earlier Ten-Tec rigs I have owned, such as the Delta, the Corsair II, and
the Omni VI+ all
have wattmeters which attempt to show the actual amount of RF output and
reflected power
on a Bruene-type circuit. The Orion does not seem to indicate the actual
level of RF output
on the meter; rather it seems to show the percentage of full power the
operator sets - that is,
100 indicates 100% of full power as set by the internal ALC pot, which
could be more or
less than 100 watts. My experience with two Orions is that the factory
sets this level to be
100 watts.
The purpose of ALC in the Ten-Tec radios appears to be to hold the peak
forward power
at the level selected by the operator regardless of the SWR. So, while
most JA rigs, and
apparently the West Coast "competition" turn back the peak forward power
under high
SWR conditions, the Ten-Tec radios historically have maintained the peak
power set until
the rig draws overcurrent which then powers the entire radio down. If you
take a look at
the classical Motorola RF power transistor data sheets, they are specified
to provide that
power under 30:1 SWRs; there should be no need to reduce forward power in
a properly
designed solid state amplifier. The key is to maintain the peak power at
the desired limit
(100 watts forward power in this case); this means the ALC circuit will
need to change
the drive level to maintain that desired forward power as the load SWR
changes.
This is an issue for the WRTC-2010 competitors as noted on their
reflector. If the antenna
has a high SWR, the forward power may increase over the 100 watt limit
while maintaining
100 watts net power (forward minus reflected). I measured the foward
power of both
my two Orions and my remaining Omni VI+ as staying within a needle's width
of the set
forward power while the SWR went from 1:1 to over 10:1 (using monoband
antennas
on the "wrong" bands). Thus, the Ten-Tec radios met the WRTC-2010 spec
while other
radios may have to incorporate an external antenna tuner to avoid rules
violations. (See
the WRTC-2010 rules for additional information on this point about why
internal tuners
are not useful for this contest.)
There were some posts a few years back about the speech processing on the
Orion
v1 versus v2 and the effictiveness of that processing. My personal
experience has been
that while I definitely needed the external Ten-Tec RF speech processor on
the Omni VI
to be contest competitive, the internal firmware speech processing on the
Orion (level
6 or 7) has been equally effective in practice for me. I have not tried
my external processor
on the Orion, as it is waaaaay down on the list of things to do here.
Terry Zivney, N4TZ/9,
still trying to figure out the best way to get an Orion to Russia with
love...
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|