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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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3rd Jun 2020, 2:22 pm | #1 |
Hexode
Join Date: Apr 2008
Location: Ramsgate, Kent, UK.
Posts: 252
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Londex Antenna relay
While searching through my stuff I found a long forgotten pair of antenna changeover relays marked "LONDEX CCX 70X 24V.D.C."
Does anyone have the specs for these relays? The internet is almost silent about them. Adrian |
4th Jun 2020, 12:24 am | #2 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,219
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Re: Londex Antenna relay
I have had a few of these over the years and still have a BCX 50X, fitted with BNC connectors.
From memory, the number indicated the impedance, so 70CX was 72/75 ohms and 50CX was 50/52 ohms. |
4th Jun 2020, 8:41 am | #3 |
Heptode
Join Date: Jul 2012
Location: Bromley, London, UK.
Posts: 702
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Re: Londex Antenna relay
Some of those old Londex relays were fitted with Burndept sockets rather than N type. The Burndept plugs were a pain to assemble. I remember buying one relay which came with spare plugs with cut-off cable stubs and they were filled with wax to seal the inners. A picture of the relay would help but, if I am thinking of the same style, they should handle at least a hundred Watts of RF - probably more.
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4th Jun 2020, 10:20 am | #4 |
Hexode
Join Date: Apr 2008
Location: Ramsgate, Kent, UK.
Posts: 252
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Re: Londex Antenna relay
Photos attached. It was the impedance (confirmed 70-80 Ohms) and the power rating and frequency range that I am interested in. I guess the range must cover at least 0 - 30MHz with good VSWR . . .
Adrian |
4th Jun 2020, 3:58 pm | #5 |
Heptode
Join Date: Jul 2012
Location: Bromley, London, UK.
Posts: 702
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Re: Londex Antenna relay
Interesting that your relay is fitted with SO239 'UHF' sockets. These are non constant impedance types and worse at high frequencies than BNC or N-type. They could be the limiting factor in your relay's high frequency performance. However they were (are?) popular on 2-metre rigs so the relay may well be OK at 144MHz. I was going to suggest that if you or a local amateur radio enthusiast had a 2-metre TX and an SWR meter, you could put the relay in-line and see how it affects the SWR. However, most rigs are intended to feed 50 Ohm coax and aerials, so a 75 Ohm relay will be less than optimum. Might still be worth a try. My guess is still about 100W switching capacity.
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