On 5/14/2012 5:53 AM, chacuff wrote:
This comes at a time when I am trying to make sense of some problems with my
station. I'm a recent Ten-Tec convert having bought a used Orion II and
Centurion amp. Was using a Yaesu FT-1000MP MKV and a modified Clipperton L
prior. Since putting the Ten-Tec gear online my wife is complaining that I
am coming through many different things in the house (shack is in a separate
building) that I never had problems with before. TV audio in two rooms
mainly. I get complaints from her even if I am only running the rig at 100W
so I don't believe the amp is a contributor other than making the problem
stronger.
Interference with ANY audio system is caused by the AUDIO equipment,
NEVER the radio equipment. The most common cause of RFI within audio
equipment is a Pin One Problem, and the easiest fix is a common mode
choke formed by winding multiple turns of the audio cable that is
connected to the Pin One Problem through a suitable ferrite core. All
wires act as receiving antennas, they pick up our transmitted signals,
and Pin One Problems cause our signals to be coupled into that
equipment. Chokes work by killing the antenna current.
The only equipment that any transmitter could POSSIBLY interfere with is
a RADIO receiver (including the radio receiver that is part of a TV
set), but it is VERY VERY unlikely that your ham gear could be
interfering with it.
When using the amp I drive it with 50 watts out of the rig and tune to 1KW
peak out using CW dits as recommended by Ten-Tec. Amps not pushed hard and
neither is the rig.
Hmmm. How did you choose 50W as the drive level? How do you determine
output power? Are you using ALC between the amp and the rig? Do you
work CW or SSB or both? What does the interference sound like to your XYL?
The RIGHT way to set drive level to any power amp is to first start with
a drive level a bit less than needed to get full power out, tune the amp
for max out, increase (or back off) the drive until you get the desired
output power, then retune the amp if you've changed the output power
very much.
Ten Tec amps have peak-reading LEDs to show amplifier power output, as
well as an analog meter driven by circuitry that may or may not catch
peaks of power, and both of these indicators have an internal
calibration pot that may or may not be properly adjusted. External power
meters that CLAIM to read peak power may or may not do that very well.
My grounding system is very robust...near commercial/cellular spec for
lightning protection and all equipment is bonded to it. Really nothing has
changed in my station except the transceiver and amp. Antennas are resonant
on 10 thru 20 and 40. (Force 12)
The only thing earth connection of your ham station has has to do with
RFI is that can change the way a long wire antenna works. It's very
important that it be grounded, and how it's grounding is critical, but
it doesn't help or cause RFI with a transmitter feeding a transmission
line.
I plan to put my spectrum analyzer on the air next chance I get and see just
what is going out. I didn't expect this and am concerned about what the
neighbors might be experiencing but haven't come knocking on my door as of
yet.
That's a good thing to do to make sure you're not producing intermod
trash on the ham bands, but it's very unlikely that anything you're
doing besides producing more output power has anything to do with your
RFI issues.
Old rig was a 200W version of the MKV run at about 125 watts into the amp
that was tuned up tight to about 900W out. I was pushing it much harder. I
never ran the rig in Class A due to the heat and stress it created on the
finals.
I don't think any of this has anything to do with your RFI. Rather, I
suspect that something has changed in your home entertainment setup
between the time you ran the old setup and the new one. Perhaps you
added a connection between the TV and the audio system. Or perhaps you
changed the cables connected to that system -- a new piece of equipment,
a new cable box, a new outdoor or indoor antenna, etc. OR, perhaps the
RFI happened when your beam was pointed to it and you didn't point it in
that direction before at times the XYL was using the TV that way.
My RFI tutorial offers both a detailed discussion of how RFI occurs and
detailed recommendations for fixing it.
http://audiosystemsgroup.com/RFI-Ham.pdf
73, Jim Brown K9YC
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