What is traditionally best coax for 800mhz scanning

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Ubbe

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You can get very low loss VHF/UHF transformers that are a lot better than the typical and lossy TV transformer.
I have serveral tv baluns from 50MHz-600MHz antennas but haven't measured their performance.
Do you have a source for high quality VHF/UHF baluns?

/Ubbe
 

bobsav21

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School me

I'm going cross eyed reading coax spec.s and I'm confused about this
Nom. Attenuation:
Freq. (MHz) Attenuation (dB/100m)
10 1.9686
50 3.6091
100 4.9215
200 6.562
400 9.843
700 13.124
900 15.4207
1000 16.405
2000 24.6075
2250 26.248
3000 32.1538
4000 39.7001
Does this mean that this coax 900Mhz loss is 15 Db at 100 Meters.???
 

jonwienke

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Yes. Coax loss depends on frequency, and the higher the frequency, the greater the loss.
 

bobsav21

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Meters/feet

Ok sorry, the reason that chart threw me is that I thought it was loss per 100 feet.
I couldn't believe how high those numbers were.

Turns out it's loss per Meter ,,, big difference..

I put my reading glasses on...
 

prcguy

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A 4:1 balun will get you from 50 ohms to 200 ohm, you would need a 9:1 to match 450 ohm ladder line to 50 ohm coax.
prcguy

Looks like this BALUN is limited to ~30MHz 160 meter to 10 meter HAM band. An old TV BALUN may work. The old ones would have covered up to about 890Mhz for channel 83. The new ones may be limited to lower. Hopefully the specs will tell the upper limit.
 

KD4UXQ

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A 4:1 balun will get you from 50 ohms to 200 ohm, you would need a 9:1 to match 450 ohm ladder line to 50 ohm coax.
prcguy
I didnt suggest using ladder line. Only responded to the balun post. You could certainly use 300 ohm twin lead and 50 or 75 ohm coax for receive. We are not concerned about return loses since transmitting is not involved.
 
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