| Author |
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814
| | Posted on Monday, November 05, 2001 - 8:57 pm: | 
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I recently got a KL200P from Copper. Great little amp. But, I couldn't get more than 120 watts on sideband!! No matter what. I disconnected the amp and decided to check the output of my radio without the amp. The meter hardly budged with the 3 foot Mini-8 jumper that I got from copper. What is this? My radio is supposed to put out 10 watts on AM stock. But the radio was supposedly peaked. I swapped the jumper for a Belden 3 foot jumper I got from ebay. 15 watts! I cut the connectors off the cable I got from copper and soldered on some PL259s that I had gotten a while back. When I cut the connector off, I noticed that the cable wasn't a shiny copper color. It was tarnished. I cut off another inch and found some good shiny copper. Soldered it all together. Tested it with a cont. meter. Slapped it on the radio trough the amp and SWR/WATT meter. Dead key on AM, 15 watts. Turned the radio all the way down, flipped on the amp. I was able to get very close to 200 watts on SSB now. About 195. Not quite 200. But the cable was causing a loss of 60+ watts! I think the amp was running cooler after also. Not sure about that though. Funny how the cable didn't effect SWRs any. Can't find lost wattage? Check your cables. |
Matt
| | Posted on Wednesday, November 07, 2001 - 12:58 pm: |
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Thanks for the Info! |
Marconi
| | Posted on Friday, February 01, 2002 - 3:57 am: |
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814, you are exactly right, if your cable has some losses due to weathering, they will not necessarily show up as SWR.
I just took down an old Starduster that had clear cover Mini8 coax. I was concerned that after about 10 years up in the air that some green discoloration in the line might be causing some performance problems with the SD'r. I checked the line with a dummy load. I placed the meter at one end of the line and then the other. With the meter at the radio end, it showed 4 watts out. With the meter at the dummy load end of the line, it showed less that a 1/4 watt. T
The line was 100' 6" long and should have showed about the same at both ends. I was able to work locally "So-So" and I never noticed a problem working skip under this condition, so I wonder what that says about the need for power?
Well, I cut the jacket off of a real bad spot and the shield seemed to be in good shape, but the inside of the jacket was discolored. I also noticed a breakdown in the foam dielectric, it had small cracks in it. The foam cable is noted to be vulnerable to moisture, maybe this is what happened that caused the attenuation. Something was going on that was not easy to detect.
So guys, check those lines.
Marconi |
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