Posted: 4/11/2014 4:06:21 AM EDT
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Equipment setup Astron RS-35M to IC-7200 to LDG IT-100 tuner to 25' RG-213 to current balun to home made ladder line to OCF 45'/90' antenna.
IC-7200 set up for RF output 100; Tuned for a SWR of 1:1 When transmitting RS-35M shows about 5 to 8 amps - according to specs should be near 22 amps for transmitting at 100 watts. Tried speech compression on and got it up to about 10 amps. How do I set this thing up to output near 100 watts when I transmit? I am getting tired of not being heard, having to repeat multiple times, not being understood, etc. If the bands are good I can contact stations but it doesn't appear like there was any difference between RF Power 50 and RF Power 100 as far as the RS-35M current meter was concerned. |
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Equipment setup Astron RS-35M to IC-7200 to LDG IT-100 tuner to 25' RG-213 to current balun to home made ladder line to OCF 45'/90' antenna. IC-7200 set up for RF output 100; Tuned for a SWR of 1:1 When transmitting RS-35M shows about 5 to 8 amps - according to specs should be near 22 amps for transmitting at 100 watts. Tried speech compression on and got it up to about 10 amps. How do I set this thing up to output near 100 watts when I transmit? I am getting tired of not being heard, having to repeat multiple times, not being understood, etc. If the bands are good I can contact stations but it doesn't appear like there was any difference between RF Power 50 and RF Power 100 as far as the RS-35M current meter was concerned. Is it showing 5-8 amps on SSB...or with a carrier? I don't think you should be drawing 21A on SSB. Do you have an external wattmeter? Do you have an antenna analyzer to see what might be going on the the antenn? Is it a homemade antenna or did you buy it? |
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Is it showing 5-8 amps on SSB...or with a carrier? I don't think you should be drawing 21A on SSB. Do you have an external wattmeter? Do you have an antenna analyzer to see what might be going on the the antenn? Is it a homemade antenna or did you buy it? Showing 5-10 amps on SSB. No external watt meter, may need to get one just because. Homemade wire antenna, length based on the Buckmaster OCF. Do have an Antenna Analyzer and also modeled the antenna and ladder line with 4NEC2. Antenna analyzer was giving me strange readings - real high impedance but the tuner seemed to tune it OK except for a couple bands. |
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Well appears to be much ado about nothing because I don't/didn't understand what SSB was doing. The whistle got it up to about 15 amps, probably could have gone 20 if I whistled louder & longer.
This review IC-7200 review shows the PEP speech envelope oscope waveform for SSB - like RaySheen said SSB wouldn't run 22 amps normally. Probably doing OK, band conditions suck when I can't get through. |
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The current draw you saw is an average. The needle can't respond quickly enough to show voice modulation peaks. What you are seeing is perfectly normal.
Also, some think that something must be wrong with their radio as they can only do 25-40 watts on AM. That, too is normal. What is your output without speaking into the mic? It should be ZERO. That, too, is normal. Remember that the magic of SSB is that the output of the radio, and therefore power consumed, is directly in proportional to the voice modulation going in. No more power that is needed is being consumed or put out. You are not the first to make this observation and panic that your radio is not putting out. Also, with my amplifier, which is rated for 800 watts, and does that with a steady signal, shows 200-300 watts on the external SWR/power meter as I talk. --- Edited: BTW, you've got a good set up there. While I prefer a smaller supply, like the Samlex line, there are an equal number of hams that like that Astrons. They have certainly proven their worth over time. And you have my favorite little tuner, too... and a good antenna, it sounds like. You are in good shape and should be able to make some good contacts. |
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... it doesn't appear like there was any difference between RF Power 50 and RF Power 100 as far as the RS-35M current meter was concerned. While there is a 50% reduction in power, that is only a 70.7% (ratio is 1/2 sq rt of 2) of the 100 w current draw. Example: 12 V x 8.33 A = 100 w (12 V x .707) x (8.33 x .707) = 8.49 V x 5.89 A = 50 w So, current draw was reduced from 8.3 A to 5.9 A. A 50% reduction in power results in a signal that is only -3 db, a half S-unit (which is considered to be 6 db). Again, normal. |
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Quoted:
The current draw you saw is an average. The needle can't respond quickly enough to show voice modulation peaks. What you are seeing is perfectly normal. Also, some think that something must be wrong with their radio as they can only do 25-40 watts on AM. That, too is normal. What is your output without speaking into the mic? It should be ZERO. That, too, is normal. Remember that the magic of SSB is that the output of the radio, and therefore power consumed, is directly in proportional to the voice modulation going in. No more power that is needed is being consumed or put out. You are not the first to make this observation and panic that your radio is not putting out. Also, with my amplifier, which is rated for 800 watts, and does that with a steady signal, shows 200-300 watts on the external SWR/power meter as I talk. --- Edited: BTW, you've got a good set up there. While I prefer a smaller supply, like the Samlex line, there are an equal number of hams that like that Astrons. They have certainly proven their worth over time. And you have my favorite little tuner, too... and a good antenna, it sounds like. You are in good shape and should be able to make some good contacts. Thank you for the setup comment (and also the explanation of what is going on in SSB) - got quite a few of my ideas from here as far as equipment. I started to panic when I couldn't get through or was not understood by W1AW portable this week. Figured I was lucky the other times and didn't have something set up properly now. Also didn't realize that the S meter on the IC-7200 was also for transmitter power output - I suppose I could have looked at that instead of the RS amp-meter and felt better about this. Live and learn. |
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You could also set it to CW mode and turn the power up to 100%. Key it down and check current draw. It will do 100w in CW mode unlike AM where carrier is restricted.
Jup is right too when he says you won't see peak current on an analog meter. I like an oscilloscope for looking at RF output. 
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Quoted:
You could also set it to CW mode and turn the power up to 100%. Key it down and check current draw. It will do 100w in CW mode unlike AM where carrier is restricted. Jup is right too when he says you won't see peak current on an analog meter. I like an oscilloscope for looking at RF output. This is what I do to check output of rigs. |
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Single Side Band has no carrier.
In an AM signal all voice information is in the sidebands. In SSB the carrier is filtered out. Since the two sidebands are mirror images, only one is needed, so the other is filtered out. All power is in the one sideband. A 100 w SSB rig is as effective as a 1000 w AM rig. |