Puma RF interference AM radio

[Rick Fischer]

AM radio

In Canberra local stations such as 666 and 846 no problem. However when trying for 702 in Sydney from Canberra, vehicle generated RF interferes. This will be a bit of a problem when I install my HF. Is also a problem for distance listening. Also occurs ignition on, engine not running, and the interference cycles up and down over a 3 second period.

Preliminary investigation with my little portable RF detector (trannie) indicates that the emission is from the RH side, and is not the engine computer. The engine itself blocks the emission on LH side. Items in the RH locale are the MAF sensor, the turbo variable inlet guide vane actuator, and the ABS.

Also interesting is that when the rear window de-fog is selected the interference drops in volume indicating that somewhere there may be a faulty earth.

Clues anybody????

Cheers

Rick F

[Rick Fischer]

Looks like I have found the problem. :)

For future reference:

SVX comes with iPod interface. In mine the iPod cable had been removed. It is a threaded connector with a good RF opening. Insulated the open metal end and then wrapped the end in Alfoil and taped over. Also Earthed the radio chassis.

One of them fixed the problem.

Cheers

RF

[Rick Fischer]

What a crock. RF Noise is back.

Reckon there must be a "loose" somewhere and when I was fiddling behind the radio I did inadvertently fix it, but has come off again. :(

Will be checking the ABS earths on GB and other earths on firewall.

No one else out there had this problem???

RF

[Mundy]

I have a lot of issues with interferrence with 702 in Sydney, to a slightly lesser extent with 576 and in a minor way with the others on the AM band. Its been very frustrating. Thought it was the window aerial (I have a Disco). I mounted an external glass mounted aerial (with amplifier) which has highlighted that there are 3 different issues: the gain from the aerial, the amplification and filtering of the signal, and lastly the effectiveness of the head unit.

The signal strength from the new aerial is better than the OEM window aerial, so I get reception for further distances. I also get much better reception with the new aerial when the radio is on and the ignition off (amplifiers don't work with ignition off). However, I'm getting poorer quality of reception. The OEM amplifier and radio gives better quality sound and less interferrence (but still not good).

The instructions for the new aerial referred to metalised window tint being a reception factor. Does anyone know if all/most window tints are metalised? What effect does the metalised window tint have on the reception?

It has been suggested to me by others on this forum that the quality of the head unit is more important than the aerial for best reception. I'm happy to buy a new one but want to understand/solve the signal reception issue first before spending a lot of money on something that may not give a better result.

[numpty]

My Td5 Defender has very poor radio reception at best and also suffers from interference. This may have something to do with the fly by wire throttle as it is worse during acceleration.

A new head unit is on the cards at some time.

[PhilipA]

[QUOTE]It has been suggested to me by others on this forum that the quality of the head unit is more important than the aerial for best reception. I'm happy to buy a new one but want to understand/solve the signal reception issue first before spending a lot of money on something that may not give a better result [QUOTE]

IMHO I am pretty surprised that anyone would expect AM reception in Canberra of a Sydney station given the Topography and distance.

I was ICE product manager of Sanyo back in 1979-80 and introduced a new line of products. The common complaint from Australian customers then was that AM performance was poor. Nothing has changed.

The reason is that AM stations are like lice in Japan , North America, and Europe, and unless the selectivity of the radio was very high, listeners would often get crosstalk where adjacent stations on near frequencies would interfere.
So nearly all tuners were and are limited to 20Mv senstivity , so that selectivity issues are reduced, as increasing selectivity is expensive.

This of course is the exact opposite of Australia where we need high sensitivity .
As we are such a small market that nobody would make a special tuner for us. This is even more true now as production has gone to China , and tuners are now ICs which are probably standardised between manufacturers.

The only tuners that I know of that were made more sensitive were the Eurovox units fitted to RRCs and Disco and BMW ( which I selected as OEM ) , and of course Holden OEM that were supplied by Eurovox. AFAIR they were 10Mv senstivity, as any more became very expensive.

So you are really whistling into the wind wanting good AM performance and to get Sydney AM from canmberra during the day IMHO would be pretty unusual..
I live on the Central Coast and have great difficulty as the AM signal is constantly degraded by 240 and high voltage hash, and neon lights etc as the receiver gain is at maximum so it pulls in anything it can get. I have a Mobile 1 FM helical antenna with low loss cabling and no car generated interference to speak of.
The best tuners at present are reputed to be Pioneer Super tuners and JVC, but they are still not much chop.
BTW I can get FM on the coast for sometimes hundreds of kilometers. Pity the programming is such crap.
Regards Philip A

[numpty]

I can receive Brisbane 612 (ABC) all the way to Warwick (around 180k's) in my Mazda 323, but in the Defender it drops out around Qld raceway.

[PhilipA]

I can receive Brisbane 612 (ABC) all the way to Warwick (around 180k's) in my
Mazda 323, but in the Defender it drops out around Qld raceway.

That may be so, but I doubt you will find an aftermarket unit with that performance. Maybe a Japanese manufacturer has specified a good radio seeing OZ is such a big market for Mazda.

I would love to be surprised by someone finding a good AM tuner as I have a Pioneer with Ipod control at the moment and its AM stage seems to have a problem as it has a whistle that starts at say 2000Hz and over maybe a minute rises to 8000or so Hz and sometimes back down.

It is independent of anything in the car or the location and seems to be related to how long it has been on. It only happens when the AM stage is flat out at maximum sensitivity. Based on my experience with testing these things with a Sanyo tech , I am pretty sure it is in the radio itself.

Regards Philip A

[wrinklearthur]

AM radio

Also interesting is that when the rear window de-fog is selected the interference drops in volume indicating that somewhere there may be a faulty earth

If you want, read up on tuning stubs and transmission lines for radio frequency,
the adding of more wire reducing interference, can be explained but not easily in a couple of lines of text on this forum.

Adding a radio frequency interference filter to the vehicles wiring could alter a wave form or the leading edge of a pulse into the vehicles computer, so that may lead to problems with the vehicles running.
.

[Mundy]

IMHO I am pretty surprised that anyone would expect AM reception in Canberra of a Sydney station given the Topography and distance.


I agree with you, Phillip, but I live in Sydney and get crap reception. When I drive on major roads such as the M2, Rookwood Rd etc, the station disappears and screeches under every under pass; going across the Harbour Bridge, screeching and interference. This doesn't happen with my wife's town car (Mitsubishi Lancer) whose reception is crystal clear, strong and stable under almost all conditions.

Does anyone have an answer to the window tint questions?

Is there a big difference in quality of head units in different after market brands and also compared to OEM?

[Rick Fischer]

With my Td5 I had all sorts of issues with long distance AM radio and HF. Lots of injector noise, was like being back in the Rangie with copper core HT leads.

The HF problem was solved by ditching the soldered end fitting and using professionally crimped antenna connections. Why that should be when the outer part of the coax shows an excellent soldered earth, only the radio gods know; but the crimped connectors sure did the job.

The AM was a bit more difficult. Improved the long range signal strength hugely by plumbing in a 0.8m gutter grip 27MHz CB antenna to the rear window car plug so I could use external in trips and window round home. The RF was still a pain until I found a slight shielding break in the vehicle,s coax. Still gave a good earth but open enough to let the engine RF in. Another possible area of "bad" is any other radio accessory plugged into the antenna circuit, eg MP3, CD, DVD player etc.

Had all my disco windows tinted and sun foiled when travelling, never made any difference whatsoever.

Cheers

RF

[Mundy]

.... Improved the long range signal strength hugely by plumbing in a 0.8m gutter grip 27MHz CB antenna to the rear window car plug so I could use external in trips and window round home. ...

Thanks for your reply. Not sure I understood half of it.

Are you saying you connected an external aerial wire to the OEM window aerial connector? How did you do connect to the connector?

[Rick Fischer]

I can receive Brisbane 612 (ABC) all the way to Warwick (around 180k's) in my Mazda 323, but in the Defender it drops out around Qld raceway.

Mazda's old Panasonics are excellent radios. My MX5 radio can pull 666 all the way to the top of the Clyde, or out to near Wagga. Pity is, these days AM had become "Passe", and the head units are optimised for FM Never mind that for Australia, AM MW and SW are the only ones that can do the distance.

Was advised by a radio supplier for truckies, that bang for any buck Pioneer DEH2050 MP/G and DEH59501B are the best after market AM fringe radios around. Both use the same tuning circuit.

I've used them both, the 5950 was in the D2, and West of the Divide, way out in the Centre, and across the top provided excellent AM reception out hundreds of km, as good as the Panasonic in my MX. The 2050 is in the E30.

If I can't get the SVX Clarion to fly properly then the 5950 will be going in, and it's able to drive the SVX's bells and whistles.


I'm getting back to my interference problem tomorrow when I have to have the centre dash out for something else.

[Rick Fischer]

Thanks for your reply. Not sure I understood half of it.

Are you saying you connected an external aerial wire to the OEM window aerial connector? How did you do connect to the connector?

Ahhh! I have a lathe, and I turned up a small button adaptor to fit the aerial spring clip :) Then soldered it all into a co-ax.

RF

[Rick Fischer]

Further along with the SVX. Includes a YYYYYYYAAAAAAAAGGGGGGG! moment.

Found that there is an powered aerial signal amplifier. Removed it and increased signal strength, and reduced RF interference, so looks like it is cactus. Used car warranty. :)

However, did a night drive with the the HDIs lit, that's all of them except the parkers and indicators; YAAAAhhhh/gggg moment. The HDI Ballasts murdered anything other than the local AM stations. Took advice and connected the spotties direct to battery, nearly fixed! Low and High beam to go. Looks like I'll need to further earth and then faraday cage the Ballasts.

Why listen to 702 Sydney in Canberra. It tests the reception and the amount of RF noise. Additionally one can pick up 702 over lots of NSW if you have a "quiet" enough receiver.

Cheers

RF

[Rick Fischer]

Well, finally got back to the radio; AM that is.

Replaced the OEM antenna with 900mm Axis unit using RG62 93 Ohm coax, with the antenna coax wired to earth instead of depending on the antenna base. Engine noise all but gone on 702 Sydney in Canberra (is there in the atmospherics). All now dunky dory :)

If anyone wants improved AM reception, first step is get rid of RG58 or similar 75 Ohm coax and use RG62 93 Ohm. The 75 Ohm impedance is optimised for FM.

Cheers

RF

[gavinwibrow]

I too finally have my AM reception much improved. They tell me they ended up putting another earth to/from the radio chassis as well as making sure the old signal amplifier (in the rear RHS?) did not still have power. Not 100%, but a significant improvement and I think a wee bit beter than OEM. Bradtot - your radio awaits!

[superquag]

Brings back memories... Last time I had vehicle-caused RF interference was in my first jalopy, an XR Falcon Wagon. In fairness, I was running wire IGN leads, homebuilt CDI .... and 27 meg AM/SSB CB. :eek:
Who remembers salvaged co-ax braid and tin cans over dizzy's and coils ?:p

In the mean time I've had Aussie, Jap & German cars, all with 'real' antennas. All performed perfectly with good open road reception.

Now my Classic Vogue SE has given it back to me - with interest. Hash from the HVAC motor, very faint IGN noise, trafficator THUMPS and very average range... - Its either low signal/hi-noise or motorboating front end, depending on 'Local/DX' switch.:mad:

So much for the 'state of the art', top-specc'd radio and window antenna + RF amp.

[Rick Fischer]

Check all the earths on everything, and the radio itself, Modern radios depend too much on the aerial and power earth. The Case earth is neglected. Then solder a proper earth cable to the antenna earth and take it to a good body or engine earth; dont depend on the aerial nut and washers.

Cheers

RF

[superquag]

... and re-connect the other end of the bonnet earthing strap....:o