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75 ohm in place of 50 ohm for receive only on multiple bands? Mayyyybe?

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Cruiseomatic

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Trying to put a outdoor permanent antenna on the house but all my 50 ohm coax is cheap and junk, Not to mention short. (So are the antennas' they came from.) Only decent strand I have is RG-58/U-95 Foam and that is used for my transciever. Now, I do have a LONG run of cable television coax that is 75 ohm I believe. I have no idea what type or brand, It's not printed on the sleeve. It came from Time Warner years ago when they were still in Houston. It looks and feels stout. Total run should only be about 50 ft. if that long. I do plan on putting an amp to kind of off set the loss. I would like to receive 800MHz and all bands the PRO-164 supports. Also, what would be a "good" antenna for this? All I have currently is a 3 ft. whip on a spring.
Yes, I have that much time on my hands to want to listen to all of them periodicly.
(It helps when momma wants to hear other states and local PD. Really helps when she wants to get on SSB and run skip. Wait until I get my amature radio license. :D )
 

LtDoc

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The two biggies with coax feed lines is losses and characteristic impedance. You want to keep the losses as low as practically possible. And while impedance isn't much of a biggy with receivers it doesn't hurt to give that receiver what it expects to 'see' as far as feed lines go. You'll probably do just fine with 75 ohm feed line.
Transmitting feed lines are a different story, Transmitters are more 'picky' about impedance. Sticking to 50 ohm impedance coax is a pretty good idea with transmitters.
Receiver pre-amplifiers are sort of tricky, meaning in most cases they don't do much good except when they are specifically designed for particular frequency ranges/bands. There are no 'cheap' "one size fit's all" pre-amplifiers to cover a bunch of bands. Spend the cost of that pre-amplifier on getting your antenna higher. (That last part is an opinion so take it for what you think it's worth.)
- 'Doc
 

Cruiseomatic

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Thanks Doc. I totally agree with TX impedence has to be exact. Learned that with cb in past years. I was thinking about getting this in a couple of months: AOR SA7000 Wideband Antenna and replace the 75 ohm with Belden 9913 for both my transciever and reciever. I just hope the Belden can hold up to amature power. But for the time being, The 75 ohm "should" work?
 

prcguy

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The SA7000 is not for transmitting, especially on HF!
prcguy



Thanks Doc. I totally agree with TX impedence has to be exact. Learned that with cb in past years. I was thinking about getting this in a couple of months: AOR SA7000 Wideband Antenna and replace the 75 ohm with Belden 9913 for both my transciever and reciever. I just hope the Belden can hold up to amature power. But for the time being, The 75 ohm "should" work?
 

N9JIG

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I have had much better luck using 75 ohm coax for scanners than 50 ohm. I found a great deal at RadioShack for a quad-shield 50 foot length with F connectors and they worked perfectly and far surpassed the RG58, RG8 and 9913 I had used on the same antennas previously. I re-tasked the 50 ohm cables to some 2-way antennas and everything works great.
 
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