But from TT pin 4 still has 8 or 9 volts. You still have to use the mic plug
shell for ptt shield/ground unless you do the Heil mod.
John N1JM
-----Original Message-----
From: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com]On Behalf Of N0KHQ@aol.com
Sent: Monday, May 30, 2005 12:42 PM
To: tentec@contesting.com
Subject: Re: [TenTec] Heil Orion mod
On the back of the circuit board that has the 4 pin foster plug make sure
that you cut the trace that is carrying the 9+ volts to pin #4. And then
solder
a wire (I would use 14ga wire-lamp cord) to pin #4 long enough to get to a
good close chassis point ground.
In addition to this I would solder a 0.01pf cap from pin# 1 (audio send +)
to pin#4 (chassis ground) this cap will allow for audio frequency's to pass
but will not allow for radio frequency's to pass, they will taken straight
to
ground and not allowed to enter the audio chain.
If you have a later Orion, manufactured after May or June of 2004 the above
mod is not required. If your not sure that your Orion already has a
balanced
mic input, take an ohm meter and measure the resistance from the Orion mic
shell to the ground wing nut on the back of the Orion. If your rig has the
factory ground mod, then your meter will read a direct short, if not the
meter
will read an open and the above mod is required.
Now to the mic. If you are using a mic wiring setup (XLR) that has 3 wires:
Audio Send + (pin #2), Audio Return - (pin#3) and Ground (pin# 1) you will
want to make sure, on the solder side of the XLR that pin# 3 is NOT jumped
to
pin# 1. If it is cut the jumper.
>From my testing here, using the PR-40, Goldline Pro and Heritage mics very
good audio can be achieved by 1st using the Orion TX-EQ to balance out the
audio and then setting the Orion SP to about 2. This is easily seen using a
PC
based Spectral Analyzer like SpectraPlus or Hamalyzer. Set the Orion low
roll
off to 50hz and the TX bandwidth at 3K to 3.15K. Just remember that low
audio
frequency's (50hz - 100hz) carry the Power of speech and the higher
frequency's (2K to 3K) carry the intelligence of speech. Its important the
these
frequency's be balanced. Too much low and people will have a hard time
understanding what you are saying, too much high and it will sound like you
have your
shorts pulled up to high. Balance, balance, balance. You will want to
strive
for the low frequency's and high frequency's to gradually roll off nicely,
not
sharply.
On my Orion, the ground wing nut has a 12ga wire running from it to an 8'
ground rod outdoors and is in no way tied to anything carrying RF
frequency's
or AC grounding. Its what I call my DC Ground.
Have fun and take your time.
73
John / N0KHQ / St. Louis
http://www.hamuniverse.com/antennas.html
http://www.cebik.com/moxon/n0khq.html
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