[TenTec] Argo V on PSK

[Gary Hoffman]

George is right about one thing for sure.... if you overdrive the radio, you
will generate a mess.  Just look at the waterfall display in psk mode on
some
of the people on the band.  Some of them take up half the display with
rubbish
on both sides of their signal.  More isn't better in this case.  And, psk is
so
efficient that high power isn't needed.

73 de Gary, AA2IZ


----- Original Message -----
From: "George, W5YR" <w5yr@att.net>
To: "Mark Erbaugh" <mark@microenh.com>
Cc: <tentec@contesting.com>
Sent: Monday, November 04, 2002 5:58 PM
Subject: Re: [TenTec] Argo V on PSK


> With the PSK31 signal in IDLE, it is a two-tone which has a peak to
average
> power ratio of 2:1.
>
> So, your output will show 10 watts in idle - when not sending any
> characters from the keyboard - while the peak power will be the 20 watts
> maximum that the rig is capable of putting out while meeting specs on
> distortion, etc. I do not know why your Argo only indicates 10 watts
output
> in TUNE, unless you are saying TUNE when the program is actually in IDLE
> mode.
>
> It is like sideband, in that if 20 watts is the peak power limit, the duty
> cycle of speech  - combined with the time lag in meters, etc. - is such
> that you may indicate only 3 - 5 watts output while talking. The two-tone
> signal has the convenient math property of that 2:1 ratio so that we know
> exactly what the meters will read when that is the signal form and *there
> is no distortion*.
>
> If you have a good peak-reading wattmeter, set up the rig to output a 20
> watt PEP signal with the PSK31 IDLE signal. Now, switch from PEP to
Average
> Power and you should see the meter reading drop to 10 watts. IF it does
> not, either you have distorted the waveform - usually by overdriving some
> stage and flat-topping or clipping the waveform - or your wattmeter is not
> properly displaying the difference between PEP and average power.
>
> YOu may well find that you need to reduce the PEP output of the Argo to
> around 10 watts under IDLE conditions in order to obtain  low 3rd-order
> distortion products. I run my Icom 756 PRO at no more than 40 watts PEP
> maximum on PSK31. Above that, the IMD increases too much. Usually output
is
> actually only 30 watts PEP or 15 watts average on IDLE. Get better
than -35
> dB IMD readings that way.
>
> 73/72, George
> Amateur Radio W5YR -  the Yellow Rose of Texas
> In the 57th year and it just keeps getting better!
> Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> K2 #489      Icom IC-765 #2349     Icom IC-756 PRO  #2121
>
>
> Mark Erbaugh wrote:
> >
> > What experience have folks had with the Argo on PSK31? I've made a
couple of
> > contacts, so I know that it's working.
> >
> > I used the same interface that I use for PSK31 with my Pegasus (the Argo
V
> > has the same connector). My interface includes pots to adjust the Tx
level,
> > so it wasn't a problem to compensate for the mic level input to the
Pegasus
> > and line level into the Argo.
> >
> > Adjusting power was tricky, or maybe I don't understand it.  With the
Argo
> > power set at max, I put my PSK31 software (Digipan) in TUNE mode and
> > adjusted the audio level until the ALC light was out but just on the
verge
> > of coming on. I assume that this is the max level before the signal
would
> > start to be distorted from ALC action. The max power (according to the
> > Argo's meter) was only around 10 watts. Shouldn't it be 20 watts, which
is
> > what I get key down CW?
> >
> > Then if I back off the Argo power, the ALC light starts to come on and I
> > have to back off the audio level. It looks like there's really no reason
to
> > use the power setting, just leave it at max and adjust the audio level
to
> > get the desired power. Would this work?
> >
> > 73,
> > Mark
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