Connecting Masthead Amp, Cable Length

[frank1985]

Hey gents. I'm looking to install a masthead amp to the old folk's TV aerial outside their garden cabin. The current setup is a 10 foot long coaxial cable running from the aerial directly to the tv in the cabin. I want to of course install the amp between the aerial and the Power-supply/TV - however, there's no way of disconnecting the coxial cable from the aerial end, i.e. it seems to be fixed in place (AFAIA). This prevents me from using a short cable from Aerial > Amp, with the longer cable going from the Amp through a hole in the cabin, and into the Power Supply/TV (I have f-connector adapters). I would have to use the existing 10ft cable to connect to the masthead amp, then another equally long cable going into the cabin. Question is - would the unnecessarily long cable connection affect the signal quality in any way? I realise I could cut the existing cable and install the connectors manually, but I'd like to avoid this if possible. The TV engineer fella was quoting 150 quid just for the masthead installation!! Seems a bit steep to me so I'd rather try it myself.

https://i.postimg.cc/xjB60v9n/aerials.jpg

 

[pc1966]

You are right that the whole point of a mast head amplifier is it sits at the mast close to the antenna so you get the highest signal/noise ratio by raising the signal level before it gets lost by the cable down.

However, with only 3m or of cable from antenna to TV I would not see much advantage from a mast-head amplifier unless either the TV is quite deaf, the cable atrociously lossy (or there is 50m coiled below the floor...), or you have a splitter for multiple TVs adding significant losses end-end.

If reception is poor recently check for water getting in and corroding the cable, etc. If it has always been rubbish then probably you need a bigger antenna and/or taller mast to clear any local obstacles.

 

[UNG]

Following on from @pc1966 comments have you got your aerial pointing to the right TV transmission mast and is it correctly polarised

 

[Lucien Nunes]

Agree with the above that you should look to the aerial installation before adding an amplifier. Masthead amps are useful for overcoming long cable losses and driving passive splitters, but don't help a lot if the limitation is the aerial rather than the cabling. The masthead amp adds a dozen or two dB of gain and the TV's AGC lowers its gain to compensate; you are just moving the gain from within the TV to within the masthead amp. If the signal is so low that the TV does not have enough gain even with its AGC wide open, then the masthead amp will add considerably to the noise and you might get a strong but unworkably noisy signal.