Thread: hf ssb codan on td5 and injector noise

I hate to say it, but the issue my be more serious than a few ferrite beads can fix.
Friends of mine with a Td5 have abandoned their HF because the noise makes it useless, and knowing these guys they will have tried a few things first.

Maybe if you shut the engine down when you need to use the HF the noise may go away

I used to install HF's in all sorts of vehicles and boats and when the TD5's came out after much grief we gave up trying to lower the electrical noise to a usable level when the engine is going, simply put nothing works enough to lower the noise to the stage where the receiver front end isn't "overloaded".
If you wish to use a HF in a TD5 powered vehicle then the engine MUST be turned off.

Apparently that was one reason various militaries didn't use the TD5. You'll need a specialist. There was a crazy story from the VKS-737 newsletter quite a few years ago about a member whose engine, (not a Land Rover), would simply die when he tried to transmit. A specialist managed to fix the problem, but the member didn't know what was done exactly. Certainly it was more than the aforementioned ferrite beads.

Originally Posted by Davo

Apparently that was one reason various militaries didn't use the TD5. You'll need a specialist. There was a crazy story from the VKS-737 newsletter quite a few years ago about a member whose engine, (not a Land Rover), would simply die when he tried to transmit. A specialist managed to fix the problem, but the member didn't know what was done exactly. Certainly it was more than the aforementioned ferrite beads.

A friend had a similar issue many moon`s ago with a 27 MHz radio in a V8 stage1 and the fix was to put a earth strap from the bonnet to the body

With a points dizzy? Now that's weird.

My 2a was a FFR - and it had bonding straps between the bonnet and the firewall, as well as suppressors on the wiper motor. Worth a try. Points ignition, generators, any brush motors, all create RFI.

One of the issues today in many fields is that with most people listening to FM radio rather than AM, and a lot more RFI generating equipment as everything goes digital, society seems to have become much more tolerant of RFI.

John

A bonnet not properly earthed acts as a radiator for any RF produced below it rather than a ground plane for the antenna.
As well as RF chokes on the power, microphone and tuner control cables right at the set and another at the tuner on its control cable, a suitable band-stop or band-pass filter may be required between the antenna and the set. The antenna may need to be relocated to the rear too.