Good quality N type 'T' connectors are essential in repeater systems for linking the cavities. The price of these new has rocketed over the last two years or so from the usual suppliers such as RS and Farnell.
I bought 6 RS Components own brand ones last year for around £8 each and had to return them because they detuned the cavity notch. These Chinese copies have a spring to connect the N male plug to the female to female socket centre conductors which limits their use to 30MHz. Not impressive for a design that should be good for 10GHz! They were exchanged for Suhner versions for and additional £13 each that worked fine.
Having used the Suhners on GB3HS I needed a further 7 for the GB7HU cavities that have been prepared for service and was astonished to find that the price had shot up to almost £350. That's more than the total income for the Group for a year, so clearly not viable. A search on the Internet through such suppliers as Rapid, Mouser, Farnell, DigiKey etc. revealed these suppliers were as expensive and most did not have stock.
However, I eventually found Connectors Cables Specialists Ltd in Harlow who were able to supply from stock a silver plated version claimed to be the equivalent of a Greenpar part for just £8.40 inc. VAT & carriage in quantities of 10. They can be found here: www.ccsukltd.co.uk and they carry an interesting range of reasonably priced RF connectors.
Having tested the connectors on the cavities I saw no detuning that I got with the RS own brand versions at a similar cost, so CCS Ltd are definitely in my favourite suppliers list.