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HF/MW/LW Equipment - For general and technical discussion of all receivers which cover the HF bands. For HF tranceiver discussion please use the Amateur Radio Equipment forum above.

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Old 01-17-2018, 11:57 AM
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Default Power Strip/ extension cord

I have my Icom R75 plugged into a power strip that is shared with my desktop computer. I was wondering if this would be effecting my reception. Here in Alaska, I cant pick up most of the stuff you guys post on here about hearing. However, I am moving to the lower 48 this spring and was looking to set my radio up close to my computer at my next house. Just wondering how much interference this might cause. I see pictures all the time of people having them running with software on a computer. So do you think this interferes? Does using a separate power outlet help? Mostly trying to hear Shortwave broadcast and Ham operators.

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Old 01-17-2018, 1:04 PM
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The proximity of the computer to the SW antenna is a lot more significant than whether the radio is on its own branch circuit.
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Old 01-17-2018, 1:22 PM
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The antenna is about 20 feet across the room going out the window. However, the antenna slopes down the side of the house about 6ft above the houses electric boxes and meters. It was the only way to rig the antenna in this home. Maybe that is why I'm hearing so much interference.
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Old 01-17-2018, 1:36 PM
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I run all my comms rigs on their own power strips with known RFI filters in them. However, the worst offender here is the high-speed/cable modem. This thing is nasty and I actually have it housed in a Faraday cage. Other than that, my cordless mouse can emit "pops" with each maneuver even on the R75 that's in the other room.
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Old 01-17-2018, 5:42 PM
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Quote:
Originally Posted by AlaskaListener View Post
However, the antenna slopes down the side of the house about 6ft above the houses electric boxes and meters.
Keep the antenna as far away as possible from electrical wiring of any kind. Noise usually more likely to be picked up by your antenna than to be coupled in through the power line. However, if you think noise is entering via the power line, try running the receiver on a battery and see what happens.
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Old 01-18-2018, 1:32 PM
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Well, I raised the antenna up from the meters, didn't have as much electrical noise. So I'll keep that in mind at my next house. Just out of curiosity, how much coax could I run from the receiver to the antenna without losing signal, right now I have 18ft of coax. I've seen them sell it at 50ft in length.
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Old 01-18-2018, 2:44 PM
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HF has very little coax loss compared to UHF. 50 feet of anything will only make a few dB difference.

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Old 01-18-2018, 11:12 PM
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Under matched conditions you can use the coax mfrs loss charts. If coax is used under extreme mis match conditions the loss can go through the roof at HF.

The worst case would be using a long run of RG-58 where 100ft might have 1.4dB loss in the 9Mhz SW band with a perfect match at the radio and antenna end and upwards of 6.5dB loss or 77% loss of signal if the match at the antenna is 20:1. This can easily happen with random length home made antennas.

If you use something like a PAR end fed SW or a 9:1 balun and 50 to 100ft of wire the match will probably be less than 10:1 and maybe better than 5:1 on most frequencies. Either way the coax loss will be more than stated in the mfrs catalog.
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Originally Posted by jonwienke View Post
HF has very little coax loss compared to UHF. 50 feet of anything will only make a few dB difference.

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