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Sunshine
| | Posted on Friday, August 16, 2002 - 10:38 pm: | 
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Hello - Does anybody know hod many watts will increase the S Unit. Someone said that 200 watts would be about a 3 S unit increase. Would 400 be a 6 S unit increase? What about 600,800,1000. ETC ETC ETC. I just got an old palomar skipper amp from ebay and on low & I set the drive to key 90 & swing 180 and on high key 300 and will swing 475. Should I keep it on low and will the tubes last longer on the low side. Where should I keep the drive control on the back? It says tune for max. If I do that it will key 250 on low and then swing down to 200. But, if I turn the drive down it will key less and swing to only 180. I guess what I am asking is how to set the Drive,Tune, And Load..
Thanks,
Sunshine |
Deadly Eyes
| | Posted on Saturday, August 17, 2002 - 12:08 am: |
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The first thing you need to know is that no two meters are exactly the same. Some are more reluctant than others. Band conditions also play an important factor.
However in general each S Unit represents 6 db.
For example if you are running say 4 watts and the meter on the receiving radio reads 3 S Units, then in order to get 4 S Units on the receiving radio you will need 16 watts transmitted on your end. For ever 3 db you double the power. 6 db is doubling twice. So 4 times two times two or 16 watts. At least that is what the books say.
In your post you seem to be a bit confused. The signal strength at the point of receiver is only one part of the equasion. You also have to factor in band conditions and the kind of antenna being used by the transmitting station. The type of antenna being used by the receiving station is a factor as well. Are you receiving a vertical or horizontal signal? Are you in the shadow of the skip or are you target central?
Once I reported, truthfully, a signal of S9 plus only to find out that the person running the station on the other end was running one tenth of one watt. Just good band conditions. So it is not just about power. It is also about how is the skip running.
However , sometimes tons of power gets you nowhere fast. For example, if you need to transmit 120 watts of power to get an S 3 but the receiver only transmitts back at 4 watts. The obvious result is that he may hear you but his 4 watts will be just too weak to be heard by yourself. If you cannot hear them you cannot talk to them. |
2600
| | Posted on Saturday, August 17, 2002 - 1:51 am: |
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I used to know a guy who would proclaim loudly "Another watt, another mile!". D.E. has it right about wattage being only a small part of the whole picture. The wattmeter is easy enough to read and understand, but nobody sells a meter to tell you "How loud do I need to be" to reach any one place. Stuff at the receiver end of the picture has just as big an influence, especially the noise level at the other end. No matter how large you are on his meter, you HAVE to be larger than his noise level. And there's no easy way to read HIS noise level at HIS end in YOUR station, either.
About that Palomar Skipper amp you mentioned. Should be a "Skipper 300", with one tube in the left rear corner driving three, usually type 8950. It may have been converted to use a different tube, since the 8950 is priced around $90.00 each these days. All the more reason to peak it right, and treat them well.
You're really stuck with having to set your carrier power on the RADIO with this amplifier. You probably won't have to turn the dead-key (carrier) level much below 2 watts. I recommend keeping the carrier COMING OUT OF THE AMP below 100 watts on High, 50 or so on Low. Don't worry about exactly how many watts the radio has to be set for, worry about keeping the carrier coming OUT under a safe lmit.
The LOAD control is set for max modulated swing. Period. The TUNE control will interact with it some. Change the peak on one, and it changes the peak setting of the other one. Going back from Load to Tune, peaking for max modulated power seems to work best on this one. You might have to go back to them a second time to get BOTH of them on the peak. The DRIVER TUNE on the rear panel should peak at the same spot, whether you check it on carrier, OR with modulation. It really is supposed to be set to a peak. If you don't, the driver tube is likely to overheat and fail preamaturely. That knob on the back is DEFINITELY NOT your carrier control. It has one particular quirk: It spins a full 360 degrees around without any kind of "end-stop". If you key the amp, watch the watt meter, and spin this knob slowly ONE FULL TURN around, you should see TWO PEAKS. Yeah, two of them. They may be very close together, at one end of the circle, or they may be at opposite ends, a half-turn apart. What matters is that you have TWO of them in one full spin of the knob. It won't care which of these two peaks you set it to. If you have ONLY ONE PEAK in that full turn, the coil attached to the Driver Tune is out of adjustment. Somebody familiar with safety issues and who knows how to get that coil back into 'tune' should take care of that BEFORE the drive tube hurts itself.
Oh, and yes the tubes WILL last longer on low side. You'll find that most everybody who can hear you on HIGH can also hear you fine on LOW side, too. Just be sure to peak the LOAD control for the side you are using. It will peak at a different spot on High than it does on Low side. The farther off from that peak the knob is turned, the more heat the tubes will have to pump. Run it too far off peak, they die young.
Enjoy,
73 |
bruce
| | Posted on Saturday, August 17, 2002 - 1:34 pm: |
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Back in the good old days.... No realy the way it started with "S" meters " S9 " was 100 UV at the reciver and each " S " unit down from there was 1/2 that in voltage or 6db power os " S8 " was 50 UV " S7 " 25 and so on. Then you had + 10 db = 500UV, +20db =1000UV and so on. NO METER CAN MEASURE THIS even the collins i had was no where near this SO to answer your question realisty as some one else said every meter is going to give you a diffrent reading since there has never been a efford to have a standard that was complyed by. Just sit back and enjoy watching it go since it realy dosnt mean a thing other wise!
Bruce |
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