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Attenuation - Poor cable?

G1ZmO

G1ZmO

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Likely a question for @Matt :)

So, I moved my antenna across to the other side of the garage roof and raised it up by 1m thinking I'd get better reception. haha

I can hear the local ATC pretty clearly so used this frequency as a reference (70cm band) and the receive strength was 5 to 6 with a 2.7m cable direct to the antenna.
I moved the antenna and routed the cable through the wall and up. 6m cable (0.5 ohm resistance measured tip to tip) but then only get a receive signal strength of 1 to 2.

Damn, I thought, maybe a poor connector joint. So, stripped off the ends and remade them and shortened the cable to around 4.5m. Now getting 2 to 3 strength signal from the ATC.

Is 'RG8 mini' cable so bad?
Should I replace it with something else?

On the plus side, I'm getting pretty good at making up the PL259 plugs LOL
 
G1ZmO said:
Likely a question for @Matt :)

So, I moved my antenna across to the other side of the garage roof and raised it up by 1m thinking I'd get better reception. haha

I can hear the local ATC pretty clearly so used this frequency as a reference (70cm band) and the receive strength was 5 to 6 with a 2.7m cable direct to the antenna.
I moved the antenna and routed the cable through the wall and up. 6m cable (0.5 ohm resistance measured tip to tip) but then only get a receive signal strength of 1 to 2.

Damn, I thought, maybe a poor connector joint. So, stripped off the ends and remade them and shortened the cable to around 4.5m. Now getting 2 to 3 strength signal from the ATC.

Is 'RG8 mini' cable so bad?
Should I replace it with something else?

On the plus side, I'm getting pretty good at making up the PL259 plugs LOL
Click to expand...
ok where do i start :rofl: ....

ive been doing some changes my self today .. ive been using RG58 mil speck for years and my brother in law talked me into buying the most expensive coax on the market :eek: which have there very own design of PL259,S ..

So after a day of replacing ALL the coax runs with a total run length of 50 mtrs ive gained 6 s points on receive and also gained plus 10db on transmit :thumbsup:



i would never have believed it if it wasnt done at my home :cool:

OK @G1ZmO what you need to understand is your handy is not designed to have a long run of coax before the signal gets to your radio so the rx pree amp is not that strong as the twig should be on top of the radio :thumbsup:

so you have a a few options

(A) buy a small rf pree amplifier like this Second Hand Moonraker MRP-2000 Scanner Preamp


(b) replace coax and plugs with these MESSI & PAOLONI PL259 for Ultraflex7 (EVOLUTION)

www.hamradio.co.uk

EXTRAFLEX BURY 7 - Messi & Paoloni Coax Cable

Purchase 100m+ and get 10% off! MESSI & PAOLONI EXTRAFLEX BURY 7.3MM/287" WHY CHOOSE THIS CABLE: • A super resistant version of Ultraflex 7, totally waterproof, buriable, anti-tear sheath, an extra petrol jelly anti-oxidation applied to the jacket, weatherproof and generally perfect for...
www.hamradio.co.uk www.hamradio.co.uk

(c) the best option is to replace coax and then buy one of these BaoJie BJ-218 25W Mobile Radio VHF UHF 136-174 400-470MHz Ham Radio Car Walkie Talkie Long Range

you would also need one of these QJE QJ1863 (10-12AMP) LINEAR POWER SUPPLY UNIT

but im sure the boffins you work with can sort you out a 10 amp 12v power supply from a pc
 
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Back working on the antennas today as i had a casualty with the high winds last week :eek:

surprisingly the 40ft mast stayed up and was un damaged :thumbsup:

but my antenna for the 10mtr band snapped in half :eek: luckily i have a spare so will be putting it up when i get back from shopping dutys ;)
 
The top of the antenna is 5.2m from the ground.
I've ordered the cable and connectors but will not do any more with this until I get them. We have the grandkids again today so it's off to the farm park.
20230415_201722.jpg
 
Fitted the 7m of ultraflex 7 and the special connectors. It improved the signal from 2-3 to 4-5. I could probably take abour 1.5 m off but don't think I'll bother yet.
 
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