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Author Topic: SB-200 with PSK?  (Read 943 times)
W1CEW
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« on: July 16, 2005, 03:59:02 PM »

I'm finally trying PSK31 and wondering about using my SB-200 at all, and if so, what is a reasonable drive level?  This mode is obviously more continuous that SSB, even though using SSB audio input.  Not sure if those 572B's are designed for that kind of service!

Thanks & 73,

Chuck
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N9VO
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« Reply #1 on: July 16, 2005, 05:10:40 PM »

Surely you jest. PSK is a "low" power mode of operation. Most stations use 20-25 Watts total power (NOT drive). You can work the world on that. Using an amp would certainly blow the rest of the signals off the map. Would probably hear from some unhappy campers.
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W1CEW
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« Reply #2 on: July 16, 2005, 05:15:16 PM »

Thanks for your humble and helpful response, much appreciated.
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WG7X
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« Reply #3 on: July 18, 2005, 07:36:05 AM »

Chuck,

N9VO was just stating the truth. Don't shoot the messenger.

PSK31, by it's very nature is a low power mode. Most operators are using, like N9VO said, between 25-40 watts out.

As a practical issue, your amp would work fine in PSK, but the higher power would tend to block many of the low-power signals in the 31 Hz passband. This would not make you a popular fellow in the PSK world.

Save the high power for other modes. PSK31 is a LOW power mode, by choice as well as necessity.

Thanks, Gary WG7X
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W1CEW
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« Reply #4 on: July 18, 2005, 07:49:53 AM »

No shooting involved.  Only commenting on tone, not content. :-)

My implied point was simply that when someone asks an innocent question to begin a reply with "Surely you jest" is akin to "You've got to be kidding!" and is the kind of condescension that makes the hobby appear elitist and arrogant, and certainly unattractive to newcomers.  I'm speaking as someone who, though licensed since 1977 has been away from the hobby for 10+ years.

I mean we are in fact talking about a fairly archane topic here, eh?  OK. nuff preaching.

In any event, I've done more listening about on 14.070 and thanks, yes discovered the low power nature of the mode.

Thanks & 73,

Chuck
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KO4NX
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« Reply #5 on: July 18, 2005, 09:55:52 AM »

Hello:

I have a friend in Australia whom I work on PSK quit frequently. When band conditions are poor, I do use an external amplifier and it does help. I have had other stations critique my signal while running around 300 – 500 Watts on PSK and as long as I do not overdrive there is no splatter.

It is true that most PSK operators use low power, but there is nothing stopping you from running more if you need the power to complete the QSO. Just be sure not to overdrive and I am sure you will hear no complaints. I guess the bottom line is although low power is the convention; there is nothing illegal about running QRO with PSK.


73


Rich, AJ3G
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WG7X
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« Reply #6 on: July 18, 2005, 10:11:37 PM »

Chuck,

No problem.

Basically, if you were to use the amp on PSK, I would drive it as if I was running RTTY in audio frequency shift keying (AFSK) mode, or SSTV.

With these 100 percent duty cycle modes, we need to check the amp manual to see if it is rated for RTTY or SSTV and drive it to those levels.

Check the manual for your amp to see what the duty cycle can be for it, and use it accordingly.

When I first tried PSK I noted the QRP mentality of the operators and decided that I would try the lower power and it worked OK, but I too feel the need for a little more power than that at times.

I just spent a day doing the North American QSO party on RTTY this Saturday. The power limit in this contest is 100 watts. It felt a little strange NOT using the amp for RTTY, which is usually a QRO mode. So... I compromised. I set the radio to 5 watts, and used that to drive the amp to 100 wattts. That way, both the exciter and the amp ran extra cool.

CU On the Green Keys!

73 Gary WG7X
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N9VO
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« Reply #7 on: July 19, 2005, 09:47:48 AM »

Chuck, No offense was intended. If your were offended, then I humbly apologize. It just seems that we all tend to get so thin skinned on everything and get offended at the least little offense. I am a SLO-code extra and there is ton after ton that I do not know about ham radio. I would like to see the waterfall when someone fires up a kw. Anyway, 73.
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W1CEW
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« Reply #8 on: July 19, 2005, 10:12:30 AM »

No problem, Jim, I think I was too quick on the trigger on my response, I agree that people are too easily offended.  With this electronic communication, we have the problem of not knowing what the emphasis is, things escalate needlessly.  My own apologies!

On the PSK stuff, I guess some people do some level of QRO, though rarely.  Seems reasonable that it could potentially be unfair to others in terms of the bandwidth usage.  I'm grateful to have learned about that in this thread. Seems like a neat mode anyway, I've now had a handful of QSO's, since this weekend.

You'll have to fill me in on the "SLO-code" form of extra, as I'm a grandfathered Advanced Class, who should upgrade one of these days, but never seem to find the time to get back into CW.

-Chuck
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W9GB
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« Reply #9 on: July 19, 2005, 03:05:44 PM »

Chuck -

Well I am a high speed Extra (earned it in 1980s with 20 wpm) .. the FCC Millennium rule making did away with the 13 wpm and 20 wpm -- and with 5 wpm and test you get the Extra.

I actually would hold on to the Advanced if I were you .... at least proves you passed the 13 wpm .. I know of 5 Advanced who are taking that approach.  Iw oudl just like an "Endorsement" - but I will have to take the GROL exams to signify that skill now!

gb  
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W1CEW
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« Reply #10 on: July 19, 2005, 03:21:08 PM »

Wow, shows how long I've been out of the loop!!  I guess I would be tempted to upgrade only because I'd like the extra frequencies on 20/15 meters.  Unless of course they have changed that too!
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W1CEW
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« Reply #11 on: July 19, 2005, 04:02:01 PM »

Off topic followup that shows my age:  Is there some standard approved "study guide" now?  They've probably got this thing down to a "memorize the questions" deal now, I imagine?

I recall having to learn a good bit about triodes and amplifier classes... that was in 1978.  I guess gone are those days!

73,

-Chuck
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N3HKN
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« Reply #12 on: July 28, 2005, 05:38:22 AM »

Too many operators turn all the knobs to the right and blast away. It does not take an amp to ruin the PSK band. A beam at 70ft and a 100w appliance running at full bore will do the dirty work. I have seen the entire PSK segment wiped out by a single signal.

It is unfortunate that it is human nature use more than we need to achieve some target of satisfaction. On the highway we ignore the cost of fuel to have a large vehicle sucking up the stuff. On the radio we use what ever our family budgets can afford to meet our perceived needs to make contacts. POWER - big engine or big amp beats the competition either on the highway or on the air.

If you cannot work PSK stations with 50 watts (or less) then I will insultingly suggest that it is time to wait for better propagation.

N3HKN
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VE7ALQ
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« Reply #13 on: August 01, 2005, 03:10:35 PM »

Let me think.  The Yaesu FL-2100b is a clone of the
Heathkit SB-200.  Both had a pair of 572B tubes with
a plate voltage of 2400 no load, 1900 or so max out
when you were pulling 0.5 amps (or less) through the
tubes (on CW, i.e. Morse Code)  My manual says to
back off the plate current to 0.2 amps if you want
to run RTTY (100% duty cycle), AM, etc.  My guess
is that you shouldn't run more than 0.2 amps through
your SB-200 with PSK-31 if you value your tubes and
your power transformer.

The conclusion of a certain thread elsewhere was that
the plates of the 572B tubes could show a cherry red,
but not yellow or white.  I have found that my 572B
tubes go flat if allowed to show any color at all. My
suggestion to you is to keep the 572B tubes from ever
showing any color, and you should be fine...
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W4DNR
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« Reply #14 on: August 05, 2005, 05:19:09 PM »

454 crew cab 3500 GMC Baby !!!!  Ill take safety over fuel economy any day.
One trip to the hospital because of a QRP Yugo offsets any savings at the pump.
( but I do run less than 50 watts on PSK )
:-)
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