KAL
Active member
OK - that might explain it. Am going to do a continuity test on the cable to see if there's a short, but also try with the emergency antenna if all seems well.
VHF probs - can anyone advise?
- Thread starter KAL
- Start date
emandvee44
Well-known member
It was £65 ex vat and you need a short cable (£10) to connect from the radio to one side of the tester - the antenna connects to the other side.
Instructions are very simple.
M
Instructions are very simple.
M
SimonFa
Well-known member
If you have a short circuit then nothing will get out as all the power is going straight to earth and not through the antenna. An antenna has a coil of wire in it which to DC is just another piece of wire but to RF has impedance (the AC equivalence of resistance) so if there is a short circuit you won't be able to spot it with a standard multi meter.
It is possible that an open circuit, say through a dry joint, will allow you to transmit and receive but there will be a loss of power. I am sceptical that DSC and receive voice would be OK but not transmit voice, but it is is possible. If you have an open circuit remake the connector to the radio and if it is soldered make sure you get a god flow of solder.
A VSWR meter is very simple as long as you have the correct insert for the frequency of operation. If it is like the ones I have used you place the VSWR meter in the circuit between the radio and antenna, as someone else says you need a short length of coax. The RF insert should have an arrow, set this to point to the antenna and key the radio and it will give you a reading of power out. Turn it round and key the radio again and it will give you reflected power. On a good system reflected power will be very low compared to outgoing power and you can do some quick calculation to get VSWR if you really want it but if you have a fault then most of the power will be reflected.
You can also get them that measure VSRW directly, in which case it will give you a green, yellow, red area. If it just gives you a number then IIRC (its about 25 years since I did any of this) a good system will give you a reading of around 1.2:1 although 1:1 is ideal. It is worth noting that VSWR is a measure of system efficiency and not necessarily a go/no go answer.
Remember that if you are testing on CH16 then you could be jamming everyone else in the area.
Finally, although a slightly different system can you call the local marona on CH80 or other users on different channels?
KAL
Active member
Thanks SimonFa; a really useful response! Much appreciated.
PetiteFleur
Well-known member
Regarding the VSWR meter, can you hire one? We hired one at Foxs in Ipswich for £10 and we checked 3 radios. 1 was ok and 2 were nok.
KAL
Active member
Not round these 'yer parts! Managed to source a meter. I might heed some advice on the retirement thread over on scuttlebutt, and hire it out to fund my SIPP!