[TenTec] O2 output level with PSK aux in

Jim M. jmiller1706 at cfl.rr.com
Wed Feb 11 01:29:11 EST 2009

You are right, when I set the drive audio until the ALC just stops flashing
on the O2 then I get about 30-40 watts out, or in that range, which is what
has been recommended by others. That's where I leave it for PSK (maybe PSK
was a bad example to use)....  So what about RTTY (AFSK)?. I would like to
get 90-100W out on that mode, since it is not as sensitive to intermod I
would imagine.  But again, the drive from the Navigator won't drive it fully
to 100W on RTTY.  The external wattmeter is a Nye Viking dual meter peak and
average reading type RFM-003.  They don't make it now but it is accurate:
http://www.eham.net/reviews/detail/2466  SWR is 1.03/1.  

I still would like to hear others' experience with the Navigator (or other
USB interfaces) driving the O2 Aux input, RTTY AFSK as an example.  Are you
getting sufficient audio drive?  Thanks to all for the comments.  Jim N4BE

-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Dr. Gerald N. Johnson
Sent: Tuesday, February 10, 2009 11:57 PM
To: tentec at contesting.com
Subject: Re: [TenTec] O2 output level with PSK aux in

On Wed, 2009-02-11 at 02:54 +0000, Jim M. wrote:
> Using HRD sound card into rear panel auxiliary input.  With speech proc
off I get only about 50 watts out with max audio drive measured on rf
wattmeter.  The O2 meter shows 100 watts, not 50.  If I turn SP on, I can
get closer to 100 watts out.  The O2 power meter appears to be reading 2x
what is actually being transmitted?  And or the drive level without the SP
is cut 50 percent?  What's going on in the DSP?  Any suggestions on how to
get an honest 100 watts on Psk? Jim N4BE
> Jim

You get 100 watts PSK by running 20 watts from the Orion into a 600 watt
amplifier. Otherwise the intermod just kills the BAND you are on, and
the other users will be wanting to shove nails into your coax. You don't
NEED 100 watts to work the world and no radio puts out clean PSK31 at
full rated power. Most do fine at 30 watts or less, and that's enough to
work the world.

Since PSK allows many RF signals in a typical receiver IF bandwidth, its
super annoying to have one super strong signal (which 100 clean watts
would be) to take over the AGC and blank the other signals. So high
power (and 100 watts on PSK31 IS HIGH POWER) is unwelcome and not

Receiving software nearly always shows an intermod level as well as
showing extra spectrum components on the waterfall display. It is
instantly clear who is running the transmitter too hard. Settle for 25
watts and you will make more contacts and friends.

73, Jerry, K0CQ

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