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De: Psk31 Digest <owner-psk31@aintel.bi.ehu.es>
Para: <psk31-digest@bipt106.bi.ehu.es>
Asunto: Psk31 Digest V1 #322
Fecha: martes 22 de febrero de 2000 4:22
Psk31 Digest Tuesday, February 22 2000 Volume 01 : Number 322
In this issue:
[psk31] Re: psk31] Wide Tuning Display
Re: [psk31] SOUNDCARD PROBLEMS
Re: [psk31] SOUNDCARD PROBLEMS
Re: [psk31] SOUNDCARD PROBLEMS
Re: [psk31] SOUNDCARD PROBLEMS
Re: [psk31] Transmit audio levels
Re: [psk31] SOUNDCARD PROBLEMS
Re: [psk31] SOUNDCARD PROBLEMS
Re: [psk31] SOUNDCARD PROBLEMS
Re: [psk31] SOUNDCARD PROBLEMS
[psk31] WINDOWS help??
Re: [psk31] SOUNDCARD PROBLEMS
[psk31] Re: [PSK31] SOUNDCARD PROBLEMS
[psk31] TS-870 OWNERS/USERS
Re: [psk31] SOUNDCARD PROBLEMS
See the end of the digest for information about psk31-digest
----------------------------------------------------------------------
Date: Mon, 21 Feb 2000 09:56:55 +0000
From: "Julian" <julian@tech-pro.co.uk>
Subject: [psk31] Re: psk31] Wide Tuning Display
I don't see why this should be a subject for flaming. No-one has to leave
the RX parked on a fixed frequency if they don't want to. Personally I like
to use the 400Hz filter of my FT-920 which can be set to a center frequency
of about 1140Hz, and I believe that it is better for the audio to be in the
middle of the filter passband rather than down one side or the other, so I
always endeavour to tune a station to about 1100Hz before calling. But I
still feel you can't beat the panoramic display with the wide filter
selected for listening around, as you say. Arguing against that is like
arguing against DSP, or dual receivers or any of the other advancements
that make operating easier, IMO.
- --
Julian, G4ILO
http://www.tech-pro.co.uk/
"Andrew J. O'Brien" <obrienaj@netsync.net> wrote:
I accidentally started a debate on the Logger reflector when I jokingly
made
a screen shot of what Logger would look like with a DigiPan style tuning
display. Judging by the private email I received, there are strong opinions
on booths sides of the issue, some love wide displays and some hate 'em.
[snip]
------------------------------
Date: Mon, 21 Feb 2000 10:01:38 +0000
From: "Julian" <julian@tech-pro.co.uk>
Subject: Re: [psk31] SOUNDCARD PROBLEMS
That's the way I do it. I don't see any ALC. However I am puzzled by why
you say that maximum power should be 10-30 watts. My FT-920 will happily
run 40-50 watts and I usually run that as my antenna is not too efficient
(not a solvable problem due to small garden and busybody neighbours.) I
always thought the only reason some people ran lower power than that was
due to inadequate heat sinking in the smaller rigs. Have I missed
something?
- --
Julian, G4ILO
http://www.tech-pro.co.uk/
"Bob Hicks" <w5tx@airmail.net> wrote:
I'm not sure but I think your process is a little backwards. I would adjust
per the following
1. Set rig power output to maximum (carrier control).
2. Adjust the audio input level to obtain the desired power output.
This provides the maximum head room for peak signal levels which keeps the
distortion down. In any case would still be around 10-30 watts for a 100
watt rig.
------------------------------
Date: Mon, 21 Feb 2000 09:44:02 -0700
From: "Gary McDuffie, Sr." <mcduffie@scottsbluff.net>
Subject: Re: [psk31] SOUNDCARD PROBLEMS
On Mon, 21 Feb 2000 10:01:38 +0000, Julian wrote:
> However I am puzzled by why
> you say that maximum power should be 10-30 watts. My FT-920 will happily
> run 40-50 watts and I usually run that as my antenna is not too efficient
> (not a solvable problem due to small garden and busybody neighbours.) I
> always thought the only reason some people ran lower power than that was
> due to inadequate heat sinking in the smaller rigs. Have I missed
> something?
40-50 watts is probably fine. Heat is not really the reason though.
Most rigs are "rated" at 100% duty cycle these days and shouldn't suffer
any ill effects at 100% power into a good match. The problem is
intermod distortion (IMD). Most rigs (but not all) seem to increase IMD
quite a bit when you exceed 50% of their normal full power. I've seen
some that didn't do well above 35%. That said, there have been a few
guys claiming to be running 80-100 watts on some rigs that I couldn't
find a problem with. IMD was good. Good for them. The fact is though,
that most won't run that high without having high IMD. This causes a
dirty signal, using more bandwidth than necessary, and possibly QRM to
others trying to operate in nearby spectrum.
Each installation seems to be different, even with the same kind of
radio. For what it's worth, I also find that pulling power back to 50%
with the power control, even while maintaining no alc, is not good
enough on my rig (TS850). While it isn't as dirty as using ALC to pull
power back, it is dirtier than running power control full power and
setting power level with nothing but audio.
Remember that SWR foldback also uses ALC, so my rule is to always have
zero reflected (that's what the tuner is for) with 100W or more output
before setting audio level for about 50W or less out. Over 50W, mine
runs about -23db IMD or worse. Below 50W, it just keeps getting better
and better with -30db down in the 25-30W area.
Gary
ag0n at arrl dot net
- --
------------------------------
Date: Mon, 21 Feb 2000 11:22:13 -0600
From: "hasan schiers" <schiers@netins.net>
Subject: Re: [psk31] SOUNDCARD PROBLEMS
Depending on the radio, the IMD is much improved running 30 or 40 w compared
to the full 100w out...even if you keep the alc from actuating. On my
TS-870, with about 50w out, I show IMDs of about 25 or so dB (suppression).
If I back down to 40w and put my amp on, I run 350w output with an IMD
of -30 dB. That may be where some of the "guidelines" are coming from with
respect to power. The exciters we use seem to be 5 or 6 dB cleaner at 30 or
40 w than at higher power levels. (This assumes all your other settings are
already optimized.)
73
...hasan
------------------------------
Date: Mon, 21 Feb 2000 13:26:06 EST
From: Charles R Greene <cgreene7@juno.com>
Subject: Re: [psk31] SOUNDCARD PROBLEMS
On Mon, 21 Feb 2000 10:01:38 +0000 "Julian" <julian@tech-pro.co.uk>
writes:
It depends a lot on the rig. I could run 50 watts to my Ten-Tec Omni-VI.
But I noticed it was running hot, so I cut back to about 40. However
on my Yaesue 757, I can run only 20 watts without the noisy fan on
the finals starting up. The Ten Tec is rated at 100 watts 100% duty
cycle and the Yaesu 100 watts at 50% duty cycle. PSK31 transmits
50% duty cycle in idle mode. The problem is that the
efficiency of the finals runs typically 62% for the two tone
signal and 87% for the single tone signal. So the power
disipated in the finals with 100 watts and 87% efficiency,
single tone signal is 13 watts. In idle with a peak power of
100 watts, the power disipated in the final is 50(1-0.62) = 19 watts.
> That's the way I do it. I don't see any ALC. However I am puzzled by
> why
> you say that maximum power should be 10-30 watts. My FT-920 will
> happily
> run 40-50 watts and I usually run that as my antenna is not too
> efficient
> (not a solvable problem due to small garden and busybody
> neighbours.) I
> always thought the only reason some people ran lower power than that
> was
> due to inadequate heat sinking in the smaller rigs. Have I missed
> something?
>
> --
Charles Greene
Amateur Call W1CG
Bristol, RI
------------------------------
Date: Sun, 20 Feb 2000 20:04:12 +0000
From: Peter Martinez <Peter.Martinez@btinternet.com>
Subject: Re: [psk31] Transmit audio levels
From Peter Martinez G3PLX
If Bob Hicks finds that there is distortion BEFORE the ALC operates,
it might just be that the ALC threshold is set too high and the PA is
clipping before the ALC does.
Some ALC's have a fast action and if these show clipping which starts
as the ALC starts, then the drive should be taken back until the ALC
action ceases and the clipping will then cease.
However, other ALC systems have a much slower release and indeed the
ALC on my TS930s is like this. I can push the drive well beyond the
ALC onset and there is no sign of clipping: the ALC is clearly
charging up quickly on the peaks and doesn't discharge significantly
in 32mS, which is the longest time between peaks in a PSK31 signal.
If you can hear the ALC releasing slowly when you overdrive with
speech, then it's probably safe to let the ALC go upscale. If in
doubt try some tests on-air, getting someone to report what happens
as you try different levels of ALC.
73
Peter
------------------------------
Date: Tue, 22 Feb 2000 07:55:46 +1100
From: Ken Jobling <k.jobling@bigfoot.com>
Subject: Re: [psk31] SOUNDCARD PROBLEMS
"Gary McDuffie, Sr." wrote:
>
> On Mon, 21 Feb 2000 10:01:38 +0000, Julian wrote:
......
>
> Each installation seems to be different, even with the same kind of
> radio. For what it's worth, I also find that pulling power back to 50%
> with the power control, even while maintaining no alc, is not good
> enough on my rig (TS850). While it isn't as dirty as using ALC to pull
> power back, it is dirtier than running power control full power and
> setting power level with nothing but audio.
......
Could power supply regulation at higher loads have some bearing on the
purity of the signal at higher power levels?
------------------------------
Date: Mon, 21 Feb 2000 15:38:33 -0600
From: "Bob Hicks" <w5tx@airmail.net>
Subject: Re: [psk31] SOUNDCARD PROBLEMS
Warblers
Lots of good comments on subject. I believe the real issue is the peak
power of the signal -- most of us measure approximate average power output
with wattmeters. Multitone power measurements are somewhat more complicated
and is most accurately measured with thermocouple type devices which are
independent of signal waveform. When in idle, the peak power is 2 times the
average
power which at 50 watts average is also the "100 watts" that most rigs are
capable. Unfortunately, my experience is that at 50 watts "average" IMD has
already risen to about -20 db depending on rig and numerous other factors.
(see http://web2.airmail.net/w5tx/psk31/)
which is less than the desired -30 db we normally speak of in SSB work. At
any rate, keep it as narrow and clean as possible and you will get better
copy but.....you won't get your worked all psk 31 neighbors award if that's
what you are shooting for...hi.
Finally, this is a good thread and to me indicates an interest in good
operator practices.
73
Bob
------------------------------
Date: Mon, 21 Feb 2000 14:54:00 PST
From: "Peter Klein" <kd7mw@hotmail.com>
Subject: Re: [psk31] SOUNDCARD PROBLEMS
>On Mon, 21 Feb 2000 10:01:38 +0000 "Julian" <julian@tech-pro.co.uk>
>writes:
>
>It depends a lot on the rig. I could run 50 watts to my Ten-Tec Omni-VI.
>But I noticed it was running hot, so I cut back to about 40. However
>on my Yaesue 757, I can run only 20 watts without the noisy fan on
>the finals starting up.
It also depends on what you mean when you say "50 watts." 50 watts of what?
Peak power? Average power? PSK idle? "Tune" button single-tone carrier?
I say I'm running 50 watts because I always set my power level to 50 watts
using the "Tune" button on PSK31SBW. I run my Ten Tec Omni VI's power
output pot at full, and control the signal level with the mic gain. 50
watts is also when all traces of ALC disappear.
This probably means I'm running 25 watts average out on Idle. I do not
measure the "idle" power because I have 3 different meters (rig, tuner, and
external SWR bridge), and they each read differently on PSK31 idle.
If the "Tune" button represents a single tone at maximum volume, and I set
that single tone to the highest level it will go without ALC action and
unacceptable IMD, I should then be OK when I'm actually transmitting PSK. I
have confirmed this with other ops who tell me my IMD measures at 30 dB or
better at 50 w and deteriorates to less than 25 dB above 60-70w.
So all you folks who run "30 watts"--are you measuring this at idle or with
the "Tune" button?
BTW, this same problem exists with Clover--different meters show a very
different power level with a Clover waveform. The solution is the same--set
things up with a single tone which is the maximum level the signal will go
to. Then when your meter reads much lower during actual operation, *don't*
crank things up to compensate.
If we all had genuine peak-reading meters that worked at any SWR, we'd be
fine, but since we don't...
BTW, all Ten-Tec Omni Vs and VIs run a bit warm on digital modes. I have
little fans blowing on or across the heat sinks of both the power supply and
the rig's finals.
73,
- --Peter Klein, KD7MW
(Note: Please reply to pklein@2alpha.net I use this Hotmail account only
as a Web gateway to my personal email.)
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