There should be a centre pin visible on the black cable, otherwise it will not work. Check its not broken off in the input socket.
Sometimes people forget to solder the centre pin, and it comes detached.
The black cable probably runs down the cavity to whichever room it goes to, or perhaps nowhere, so I would not worry about it.
The amount you have spent is nothing compared to what an aerial installer would charge to sort the problem out.
They would swap the amplifier and possibly change all the connectors to "F" type
You only need to connect the outputs that are actually going to be used, so if you only use downstairs and the bedroom, then just connect those two.
There is a centre pin showing but not the copper cable from the actual cable. I think the black one feed the bedroom but still works anyway when it was connected, I won't worry about it.
I will just connect the 2 sockets to the new amplifier that are used.
I have marked the aerial cable with green tape, living room cable with red and the bedroom with blue.
Will go for the Amazon one you suggested if needed.
It would bring your system up-to-date, as you no longer need VHF features, that was a very long time ago.
I don't think that the VHF socket necessarily means it's an ancient amplifier catering for VHF TV signals.
As you probably know, VHF is now used for FM analogue radio and DAB digital radio broadcasts. Some signal amplifiers include both UHF (for TV) and VHF (for radio) sockets. If you look at the newest amplifiers on Amazon from a producer such as Wolsey they have sometimes now renamed the VHF label as DAB Radio or something similar.
Budget/portable radios just rely on the built in aerials, but high end radio equipment such as radio components in Hi-Fi stacks will usually include an aerial input socket on the back. I believe some people install high quality VHF aerials on the roof/loft along with the usual UHF TV aerial.
If you are not using the amplifier for any radio use then you can of course just ignore the VHF socket.
Here's part of the specification of a new model Triax Wolsey signal amplifier just to make things clear.
This is a dual input amplifier allowing you to combine both your TV aerial and FM/DAB radio aerial into one cable
• Number of inputs: 2
• Number of outputs: 6
• Input frequency band: Both VHF & UHF (Freeview TV & Radio)
and here's a diagram for an SL- .... model which shows the same set up for both TV and Radio aerials.
That has a FM and TV diplexer built in, although you will not need to use the DAB input.
If you look closely at pictures of the SLx 27820HSG-4G you mentioned earlier I think that also has IN-FM and IN-UHF?
Anyway, the point was that many signal amplifiers may still have an additional VHF (possibly with a different label) input socket, but for radio usage rather than for the old 405 line TV signal.
405 line TV used frequencies between 41.5MHz and 214.25Mhz which does encompass FM and digital frequencies. I suspect the range now accepted by a modern amplifier, would be much smaller to reduce the chance of out-of-band signal overloading it.
Thanks for the further info. The amplifier was definitely causing an issue as since I have bypassed this the HD channels are fine.
If I buy the SL model I assume I fit the aerial cable to UHF? And all the 4 sockets in the house get connected to 1-4?