Uhf t connector vs stridsberg mca204m

[mmckenna]

mmckenna is probably one of the most knowledgeable and helpful people here.

Will engineer radio systems for beer.

 

[stormtracker78]

ty so much again you guys are awesome! my original plan was to use (ABR Industries LLC 218XATC-PL-BM-75 Cables Coaxial, 218XATCPLBM75 (hamradio.com) this coax with pl259 to bnc male to strisberg or other splitter/coupler and then into my 2 scanners with same grade coax bnc to bnc 3 foot jumper

 

[stormtracker78]

lol mmckenna my family is Irish and we make great homemade beer!

 

[Ubbe]

Adapters are often a weak point and will eventually give you a headache/hair loss.

You have to go to high end branded adapters to get trouble free ones. Pigtails are much cheaper and you can get them with the correct connector types at both ends at a very low price that will never fail, if you don't pull at the coaxes as the strain relief can be a bit on the weak side on the chinese made ones.

/Ubbe

 

[stormtracker78]

well Ubbe and mmckenna and all the guys got my shack radio room up and running minus the coax for the scanners been busting my head on about a 75 to 80 foot run to the scanners with my tram1410 lmr 400 versus dx engineering rg6u quad shield or something like that thought you guys might like to see a pic because your info has helped me alot thanks again

 

[stormtracker78]

btw bought the stridsberg204m so im thinking if i go with the rg6 quad shield the amplifier will balance out some of the lost signal due to mismatch but im not sure and also i dont know how to figure out impedance mismatch due to 75 ohm versus 50 in feet i know it has some to do with what frequencies and the longer the run with rg6 its not good for the receiver end my preference is air/military vhf and 800 mhz police fire ems etc does anyone know if there is a mismatch/impedance calculator in feet that shows the difference between those 2 controversial ohms like a coax loss chart in feet probably a stupid question but im not an expert in that field

 

[mmckenna]

There are ways to figure it out, but you'll be chasing your tail on this stuff.
A discone does not provide 50Ω impedance over it's complete range.
Your scanners do not provide a 50Ω match over it's complete range.

Yeah, ideally you'd keep everything 50Ω, but you'd also want to run something better than LMR-400 for 80 feet at 800MHz.
But for hobby use, budgets get in the way. You've got to be realistic about this stuff.

If you can afford 80' of LMR-400 with all the proper connectors installed, then go for it.
If RG-6 is more in your price range, then run that. It'll work and you'll still receive lots of stuff.

You can always upgrade later. Or not.

 

[stormtracker78]

Wise advice! I see you figuratively as an owl with glasses sitting in a giant oak tree

 

[mmckenna]

Wise advice! I see you figuratively as an owl with glasses sitting in a giant oak tree

Actually, sitting on the couch wishing I had a cold beer. I probably need glasses, though.

 

[Ubbe]

...does anyone know if there is a mismatch/impedance calculator in feet that shows the difference between those 2 controversial ohms like a coax loss chart in feet probably a stupid question but im not an expert in that field

It's a 0,2dB loss at each junction where there are a 50 ohm device that connects to a 75 ohm device. If an antenna are 50 ohm, they seldom are, and a scanner are 50 ohm, they never are, and you use a 75 ohm coax you will loose 0,4dB of the signal.

There are coax charts that get you the loss of different coaxes for a 100ft lenght at different frequencies. The chart show different values for the same type of coax as coaxes comes in different qualities. Charts usually says 6dB loss for RG6 and 4dB for LMR400 at 900MHz and 100ft. That's 5dB and 3dB respectivly for a 75ft run, if we add the 50 ohm 0,4dB mismatch to the RG6 coax. And that are at 900Mhz and lower frequencies will have less loss, like 2dB for RG6 and 1,5dB for LMR400 at 150MHz.

The Stridsberg multicoupler are for splitting signals that already are received with a good signal strenght. If you want maximum reception of weak signals you should fit a low noise amplifier at the antenna and then a passive splitter at the other end of the coax. You then do not need to worry about loss or impedance mismatch and the amplifier has a lower noise figure than scanners and will help reception even more. The amplifier needs to be able to handle big signals without overloading and will also need a power source and the full gain of the amplifer cannot be used and has to be attenuated before going to a scanner.

Newer scanners like Unidens SDS seies show signal strenght in dBm. You can then check what a 6dB loss and what an additional 7dB loss of a passive 1-4 splitter will do to the signal. If everything you receive are at a -80dBm level you do not need to worry about a 15dB total loss in the antenna system as a -95dBm signal are almost noise free and can be received without any problems.

/Ubbe