Long range radio reception

Having been the ICE manger of Sanyo in the early 80s and later the guy who selected Eurovox for OEM fitment in BMW, maybe I can help a little.
IMHO from observation some of the best tuners around at the moment are the factory Holden tuners, which I think are/were Eurovox a couple of years ago.
From observation the Pioneer "Supertuners" are great on FM but like nearly all others are crap on AM.
The reason for this is that Australia is about the only place that AM sensitivity is an issue. If you have good sensitivity in Japan, USA, Europe, you have a BIG problem with cross talk, as there are so many stations, and it is expensive to have good selectivity. Even then you may have a number of stations on the same frequency within a couple of hundred Ks.
You can improve matters greatly by buying a dedicated high performance FM aerial. I think it is Mobile 1 makes them, or did 5 years ago when I bought mine.It has low loss input cable, and I remember getting Townsville FM for about 400Ks down the coast. But it is helical wound so does not retract.
regards Philip A

Eurovox, standard issue is not good enough for long range. We have one in our Jackaroo and it can only pick up what is broadcast locally. Had one in a Statesman which could pick up AM an hour+ after we left the broadcast area. It may have been a better version as it had a 10 CD stacker in the boot.
The radio in the Jack picks up all the engine noise on AM, so we have to listen to whatever is in the air.
That's the reason we got an MP3 player, as soon as the radio fades plug the player in and listen to our own music.
Have considered Podcasts, but you have to pay for them.
We bought a shortwave radio but there is still a lot of noise and fading at different times of day/night. A laptop with lots of options is our latest attempt at keeping up with events while off the beaten track, but will have to wait for our next trip to see if it works as a TV or not.
OzeSheila.

You can reduce the AM interference to a point by fitting capacitors to the noise sources and ensuring that all your earths are good.eg aerial at both ends, radio , bonnet to body, aternator, and so on. And that you have "R" plugs and good leads if a petrol.
Also a capacitor on the power lead of the radio may help, as sometimes the interference is through the power supply.
But some radios are just crap at filtering interference. that is generally why most car manufacturers specify speakers that "roll off" at about 10,000-12,000 Hz. They do not process so much interference.
I am still sometimes amazed when someone demos his"premium " sound system to me, and it sounds like the music is coming through a pipe.Sh1t speakers.

I am not a tech, but did employ one and worked with him closely on this problem in one of my previous lifes..

One of the side effects of interference is that it provides a strong input signal, so the gain of the RF stage is reduced. This means that the radio winds back on receiving a distant station, making the whole poor distance problem worse.
So if you fix up the noise, the radio will work better on AM.
But it will still be bad.
regards Philip A

Scrubitch,

Can't comment on the question of which receiver offers the highest sensitivity, but in my experience the problem isn't so much related to the sensitivity of the receiver, but the signal to noise ratio of the received signal. Local electrical noise from the alternator, the fridge, etc and ignition noise from a petrol engine, can be reduced by having good connections (especially good earth connections) and by bonding the bonnet to the rest of the vehicle. (i.e. bypass the hinge with a flexible wire from bonnet to chassis.) As has been suggested, some capacitors at the alternator and elsewhere can help too. As has also been mentioned, local electrical noise (which may not be obvious to you) is interpreted by the receiver as a strong signal which will cause it to reduce sensitivity.

Doesn't help when travelling, but when stationary in a remote area I extend the aerial by connecting a few metres of wire to it and throwing the insulated wire up into a tree. Makes a big difference.

HTH

John

Hi Scrubitch

Support what Phil and John say and can add from point of view as Astor/Philips radio design engineer in 70's that radios sensitivity was progressivily designed out from 1 mircovolt (12v valves) to 3 microvolt (transistor units with tuned RF stages) to 20 microvolt in the eighties, this was primarily done as number of local stations increased and noise pollution from cars and internal microprocessors increased.

One non CD solution is to pick up a radio from a 70's car at the wreckers.

Most early radios had a variable capacitor on the rear , usually with a knob to trim tune there input aerial coil.

Its vital that this be tuned on weak signal for peak output , and the presence of this trimmer is an indication of a better radio.

Robin Miller

Hi scrubitch,

These days most AM car radios have a sensitivity of about 18uV/for a 10db signal to noise, say for a communication receiver of less than a 1uV for the same Signal to noise. You could always ask for a data sheet for your proposed purchase.

As other posts say increase the sensitivity of the AM receiver too much and it will pick up heaps of noise especially when your motor is running. Despite all the theories about vehicle noise suppression some interference is extremely difficult to remove.

The Eurovox in my diesel Jackaroo (not much electrical noise) was excellent and AM reception was good for 500Km. The Eurovox did not have adjustment for different external aerials you had to use the one supplied with the radio.

Cheers

BLAUPUNKT as fitted to the early model Commodores- probably wouldn't be available with CD (as this was pre CD era). Excellent long range AM & FM reception.

Talking to the radio shop about just that today where the guy reckons he specialises in longer range gear. 70s/80s Commodores had good ones but Alpine today have the best AM tuners in radios he reckoned. The cheapest he had was about $259 with a CD player, $299 for one with MP3 player. I know I much prefer to get a radio with national information on it to any MP3 player in the car or whatever.

Also have experimented with a horizontal coil of wire as an antenna. Quite a bit of information on the net. Did you ever set up an antenna between trees? Had crystal sets like that for AM. Something high too is better than low down.

Thanks everyone for your help. It probably is the AM side of things I'm interested in. Mainly in the camp at night, to keep in touch with what is going on in the world, though I often wonder why. I have been told Alpine are the best before, that is why I bought one 10 years ago. The CD side of it has packed it in, so thought I would ask around before lashing out for another one. Have checked out the Mobile One website and will probably go down that track as well. Thanks again for the advice.

Cheers Bruce

Hmmmm... a combined CD player and a decent AM/Short Wave radio is probably an oxymoron :)

In recent years I have tried a few radios but keep going back to my Sony ICF SW7600. This is not a "car" radio but a small "transistor" radio. It even comes with a neat little wire antenna in addition to the telescopic. It's not cheap (decent radios never are) but it will do all you require and, I'm sure, give you far better performance, selectivity, sensitivity, and audio than most. Grundig and Roberts are also good.

With radios I am very much in agreement with the “Get What You Pay For” brigade – so expect to pay $250+ but it will do what you want and, probably, last for ever.

Have a look here: (prices are in UKP – multiply by 2.5 for A$)
www.ogormans.co.uk/shortwav.htm

Mike Harding

Whats the go !

Who Listens to AM ? ? ?