View Full Version : Problems with 73 radio

08-19-2002, 11:38 AM

Recently I took my 73S sporto apart for cleaning. Now that I am getting it back together, the US Frankfurt five button (2 AM/3 FM) stereo radio is giving me fits. AM plays great but when I push any FM button, all I get is a hiss (variable hiss volume using the volume knob). Using manual tune gives the same result- plenty of hiss, no FM signals.

I had the fenders off, but did not unplug the antenna. Could it be that I did something to the antennna when I took the fender off? Does the antenna need to be grounded on the fender (or not grounded on the fender). If so, why does the AM play so well?

Thanks for the help guys

John/ 513 325 8071

08-19-2002, 12:05 PM

Email to Josep at oldautoradio@canal21.com, he should be able to advice. I bought my radio from him.

Good day

Roland Kunz
08-20-2002, 12:57 AM

Check if your areal isn´t grounded and if you have 0 resistance between radio ground and antenna base ground.


08-21-2002, 09:35 AM
The AM usually has a ROD type antenna internal to the radio. A coil of thin wire wrapped around the rod forms the antenna. The position of the coil is important so don't move it. If it becomes unglued the whole AM section will need to be retuned. The long and short... AM does not USUALLY use the fender mounted antenna, hence the AM reception.

As far as the FM goes... you cleaned your car. Is there any chance you pulled the connection loose from the rear of the radio while vaccuumming thoroughly? I'll have a boo at the wiring diagrams tonight.


08-22-2002, 05:50 PM
I have very little knowledge of 67's, but cars 70-73' factory equiped with AM radio's, did come with a fender mounted antenna.
John, try another antenna and cable. My guess is the very small sensitive wire in the centre of the cable is broken.

Sounds like your getting into more than just a cleaning of the car since the last time we spoke.
Veilen Gruss aus Kanada, Robert.........

08-23-2002, 09:52 AM
It may also be the case that the simplicity of AM broadcast, combined with the signal strength, is resulting in a strong enough signal input to the radio and thus reception/rectification of the signal is still possible.

FM remains a different bag of hammers for the PLL to lock in.

Roland Kunz
08-24-2002, 08:26 AM

If I remeber correct his AM section works but not the FM section.

like explained is LW/AM band antenna mostly integratet while SW/FM needs the areal.

A simple test would be to just plug in any FM antenna into the radio soket and the FM bad should receive the local braodcasters.

IF yes, it is a antennaproblem and if nothing comes in it is time to check the radio.


Jim Schrager
09-17-2002, 04:59 PM
In my experience, Blaupunkt radios of this period are very fussy, and prone to stop working at any time without notice. I have had several repaired radios break again, and have tried three different nationally known repair shops. Finally one of the guys, after his third try to make a Blau Frankfurt work, told me he thought Blaus from this period to be real junk. He also mentioned that Blau does nothing to support the old radios, and supplies no parts. The only way they can fix them is with old scrap parts. It's not a pretty picture.

09-17-2002, 06:17 PM
On a early 911, I believe aesthetics of the radio is more important than the actual sounds because there's plenty of good music coming from the engine at back. Blau with small faceplate looks better than Becker as it's slim looking, and matches the heater controls in appearance.

Click here (http://www.pelicanparts.com/swapmeet_pics/Parts_Obsolete/Pic149.jpg)

Having said that, Blau radios of the early period, even dating back to 50's, were high quality. <img src=http://www.ezboard.com/images/emoticons/smile.gif ALT=":)">

09-17-2002, 09:15 PM
Can't say much for the Blaupunkt in the photo (I'm a Becker fan)--but the interior is spectacular.