Coax cable

[M0YDH]

Hello all
What coax cable do you recommend for use a) at home shack and b) portable to go between the masthead box and the PA ? 437 MHz and 23cm versions.
I'm hoping it's a single length because I'm getting mixed messages in relation to system diagrams elesewhere. I think I need 2 coax relays at masthead in DG8 preamp style and one for Tx / Minitiouner selection in the PA enclosure. Masthead box to aerial coax is likely to be RG213 of approx 1m length.

cheers

David M0YDH

[M0SKM]

Hello David

HDF400 is my favourite.
Sold on the WiFi market and claimed to be equivalent to LMR400.

It's very cheap and our club has used it at 13cms. At home I use it at 2m and 70cm. A bit too stiff to go round the rotator so I swap to a flexible (Aircell 7) from the masthead amps to the antennas.

I use the same stuff portable; it's a lot more flexible than Westflex.

My masthead amps are RF switched. I don't run enough power to worry about them.

73 Steve

[g0mjw]

For portable, unless it is a long length your best option for 2m is RG213. There are better low loss coaxes but they tend to be less flexible or prone to damage when being continually coiled and uncoiled. 70cm probably the same for short runs but the loss of 10m of RG213 is 1.7 dB which is getting significant.

At home, again, only if significantly long, LDF4-50 or LMR-400 are good for the long leads, but not ones that have to flex. If you have a rotator you need to use flexible cable for the rotator loop, RG213. Don't be afraid of joints, as long as they are done properly and there are not too many of them. The loss should be under 0.1 dB and the return loss better than 20 dB if done right. Invest in high quality connectors, Cheap ones are probably not good enough. If you have any PL259s, throw them in the bin.

I like to keep losses below 1 dB. Here is a table of the loss per metre of typical coax for 2m to 6cm. It may get WAS garbled by the forum but you should be able to work it out.

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This is for a typical 10m length (above values x10) which illustrates that on 2m RG213 should be OK. At UHF and up or for longer lengths you need something better. LMR400 is a good choice because it is cheap and connectors are readily available.

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Mike

[M0YDH]

Thank you for the splendid answer Mike. Is cheap £3 - £5 per metre as a guide? Where do people buy LMR-400 especially say 20m? One online shop with a £3.50/m price that I found had a MOQ of 100m. I won't use that much this lifetime!

Cheers
David M0YDH

Ps that HDF400 semi rigid coax is £1.30/m including VAT so a good tip. Thanks Steve.