Typically on PSK - 31, the 100 watt PEP radios should produce about 30 to 35
watts output. AND the speech processor should be OFF and the ALC should
show NO activity. This will greatly reduce the heat build up that might
contribute to frequency instability too. Should you be running a power
amp then the output should be 1/4 to 1/3 of the PEP rating of the amp. Most
stations are running 20 to 40 watts typically on PSK-31.
If you are trying to drive a MIC input from a sound card speaker output, you
should have some 20 to 40 dB of loss inserted between the sound card and the
radio input to prevent overdriving the input stage of the radio and maintain
a good S/N ratio of the audio signal. A simple resistive T or Pi or L pad
will do the job. If the station you are working will give you a IMD
report, and most software will as read during idle, then you should get a
report of some -20 to -30 dB IMD if you have a good signal. If the IMD is
reported in the -10 to -20 dB range then it is likely you are overdriving
the input stage. The result is that your transmitter signal is wide and has
2 or more sidebands. Thus you won't be very popular in crowded bands. Or
ask the station you are working if they see any sidebands on your signal.
There should be none.
73
Bob, K4TAX
----- Original Message -----
From: "jim" <jim@itristar.com>
To: <KC2RVD@arrl.net>; "Discussion of Ten-Tec Equipment"
<tentec@contesting.com>
Sent: Wednesday, December 26, 2007 6:29 PM
Subject: Re: [TenTec] Triton IV with digital modes
I question whether the Triton's stable enough for sliver narrow PSK, but
it sounds like
you're driving the Triton so hard that the supply is nervously
approaching the current limit
knee.
It might become unstable enough to cause frequency modulation of the
transmitter. If there is a
radical DC instability, any dampening caps or voltage amplifier
circuitry between the meter
and VSWR detector might be cycling and holding up enough voltage across
the meter
coil to cause the erratic deflection.
If you are running the AFSK signal into the mic jack, set the drive up
to the normal SSB mode
setting, then regulate the transmitter to about 25W by adjusting the
COMPUTER audio level out.
If you can't get the computer audio level output down low enough to
properly drive
the transmitter, you may have to stick a 10dB pad between the computer
out and mic in,
as the computer level will often be significantly higher and too low an
impedance than what
the transmitter would like to see to develop PEP. A 10:1 T-pad should
take care of both, and
help produce distortion free AFSK sigs. Effective PSK RF power levels
are typically between
QRP to 30W.
Jim WA9Z
Louis Ciotti (KC2RVD) wrote:
I have been using my Triton IV with PSK31 and RTTY over the past few
weeks,
and occasionally something odd happens.
I tun up the radio/antenna for about 1:1 using the lock position. When I
go
to transmit using rtty/psk31 I will get a very high SWR reading on the
Triton meter, and I get a weird buzzing noise coming from the 262G power
supply. I think the rig may be going into oscillation, but have no way
to
verify this. Anyone else experience this?? I have been able to make
some
digital contact with good signal reports, but it this is with the drive
turned way down.
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