Crackly radio (fibreglass car)

[Brinyan]

I have a 1973 Scimitar GTE, with an original Radiomobil AM/MW radio. It’s really crackly, with the engine running. With ignition on (engine not running), it’s fine. Why would this be? Is it something to do with the car being fibreglass & earthing problems.
What are the options for replacing - something that looks ‘old’, but has an aux input would be good.
Cheers

[V8covin]

Probably needs a suppressor wiring in

[Lotus 50]

My understanding is that a car with a metal body provides an electrical 'screen' between the engine and the aerial and fibreglass bodywork doesn't. On the lotus twincam as fitted to Elans you can get aluminium shields/covers that covers the valley between the cams and the back of the engine and shields the HT leads/sparkplugs. I fitted them to mine and it did make a useful difference. Not sure if the same is readily available for a Ford V6 though.

Edited to add that, yes a suppressor is probably a good idea too!

Edited by Lotus 50 on Saturday 3rd September 08:28

[Scrump]

V8covin said:

Probably needs a suppressor wiring in

This

[Dogwatch]

On a car of that era I would have expected radio interference suppression to have been there from new. Possibly someone has replaced the ht leads with an unsuppressed set or an existing suppressor has failed. The dynamo is another source of interference usually in the form of a whine related to engine speed.

The fibreglass body doesn’t help as against a steel body but even steel bodied cars need ht suppression. I’m not sure that an aluminium cover would have a great effect on stopping the emissions from what is effectively a spark transmitter.

[Brinyan]

Thanks for replies. I’ll try a suppressor initially. I will look at options for a period looking more modern unit to replace the existing radio. Any recommendations on where to look for such a thing? Cheers

[Scrump]

Brinyan said:

I will look at options for a period looking more modern unit to replace the existing radio. Any recommendations on where to look for such a thing? Cheers

Some period looking options here:
https://www.classiccarstereo.co.uk/product-categor...

[paintman]

Brinyan said:

Thanks for replies. I’ll try a suppressor initially. I will look at options for a period looking more modern unit to replace the existing radio. Any recommendations on where to look for such a thing? Cheers

Ask the question on RSSOC.
www.scimitarweb.co.uk/homepage

[dartissimus]

Probably better to use a bluetooth speaker

[grumpy52]

You have to determine how the noise is being received.
With the engine running disconnect the aerial,if the interference disappears then the aerial needs earthing properly. If it is then reduced you will then need to fit suppression. Ticking that speeds up with engine revs is from the ignition system ,this is usually firstly tackled by fitting a suppression to the coil but can also require an in line suppression to the HT between the coil and distributor ,and sometimes the individual HT leads to the spark plugs .
If it's a high pitched whine that varies with engine speed then the dynamo or alternator needs suppression. The power into the music system my require inline suppression.Fit an additional earth to the system.
That's all assuming you have descent earths throughout the car . Extreme measures include a sheilded cage to mount the system in ,and fitting additional earths for every electrical system on the car .
My dreaded job back in the day was fitting systems into fuel tankers , they needed to be fully isolated to prevent sparking ,Radiomobile actually supplied special isolated range for tankers and carriers of dangerous goods.