[200q20v] Rear Pillar AM/FM Antenna Amplifier

[Martin Kuetzing]

About a year ago, I purchased a 1991 200Q 20V sedan.  One flaw that I had 
to fix was no AM radio reception.  I spent a fair amount of time combing 
the audifans archives for solutions to this problem.  One solution 
suggested was - horrors - drilling a hole to install a standard 
fender-mount antenna.  Another was an expensive antenna amp replacement 
from the dealer.
I thought I would relate how I came about to fix the problem.  Perhaps this 
will be useful to others.  Once again, there was no AM reception.  FM 
reception appeared to work fine.  The previous owner had replaced the 
orginial radio with a newer Blaupunkt with only a single antenna jack.  So, 
before trying anything else, I tried connecting one antenna lead, then the 
other, then both - through a wye-connector.  Still no AM.  Since, it was 
pointed out on the list (somewhere) that the front windshield contained 
only an FM antenna and amp, the problem appeared to be focused on the rear 
amp.  Someone, somewhere on the list gave rather explicit information about 
using a DMM to measure voltage and current at the amp - in my testing, 
everything seemed normal, but inconclusive as there was still no AM.
So, I went to a local high-end shop and agreed to pay them $15 to check the 
Blaupunkt on the bench to see if it worked for AM.  It did, so they wanted 
$150 - and the car for an entire day - to repair the amp - and $100 more to 
repair the wiring/cabling to it if necessary.  This appeared suspicious to 
me, as I figured that the amp had some specialized components in it that 
one couldn't just obtain - at say, Radio Shack, for instance.  So, I paid 
them my $15 and went home.
In removing the amp, and opening it up, I noticed a rigid, solid wire lead 
connecting the antenna power connector (on the amp's housing) to the 
circuit board.  In fact, the wire - more or less - broke off at the circuit 
board as I pryed open the amp's enclosure.  This seemed like a faulty 
design to me, in that the rigid wire was constantly subject to the stresses 
of heating and cooling - rear pillar, rear deck, sunshine, etc. - and that 
it easily could fatigue and break over time.  That is, maybe I did not 
break the connection by merely opening the enclosure.  Maybe the amp was OK 
afterall.  Maybe some of the folks in the audifans archives had experienced 
a similar failure, but didn't realize it.
So, I unsoldered the rigid lead and replaced it with a longer, stranded and 
insulated 22 ga wire & snapped the enclosure together again.  After putting 
the amp back into the car, I had - and still have - great AM radio 
reception.  I noticed no improvement in FM reception - which was fine 
beforehand anyway - so I assume that the rear amp is designed to boost only 
AM frequencies.  Further, the FM reception was not helped in any noticable 
way with a wye-connector tying both windsheild antennas to the single 
antenna jack on the radio.  And as the AM was somewhat noisier with the 
wye-connector arranagement, I settled on using just the antenna in the rear 
window.
I took a few photos of the amp - opened up - and of those remarkable clips 
that hold the rear head-rests in, as well as hold the rear seat-back in, if 
there is any interest.
Regards,

Martin Kuetzing