OK, a bit of background. I re-installed my re-furbished Hirschmann 6000EL in my 380SE, and moved the aftermarket unit that was in the 380 to my Mazda 929. The aftermarket unit has a screw-in fitting that the Mercedes coax audio lead screwed right into. On the Mazda, I needed an adapter to plug into the standard audio lead socket. The unit did include one of these, but I couldn't get any continuity in the inside wire. I put it in anyway, but got very poor reception. So, I took it out and took the plug end off. Inside there was a tiny cylindrical brown thing, marked with '221', soldered just inside the pin of the plug (resistor, capacitor??). No continuity through this thing, but the wire itself was fine. I removed it, resoldered the plug, tested for continuity (OK) and put it all back in. Now I get good reception.
My question: What the heck is it and what is it for?

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1986 560SL
2002 Toyota Camry
1993 Lexus

Just to let you know, the item is probably a capacitor use to balance the antenna to the radio input. Different antenna systems for different cars are use to pull in the best reception for their radios. One antenna may not match a different vehicle due to different manufacture specs for the radio installed.

Cleeve

A capacitor? I'm not much at electronics. Why would an ohmmeter (or ohms setting on a multimeter) not register continuity through this?
According to the installdr (www.installdr.com), and other sources, one test for an antenna is to check continuity between the ends of the lead, both inside thin wire and outside sheathing. This lead came out of a 'universal fit' Hirada antenna. It failed the continuity test on the inner wire, only because of this thing.
So, I'm posting to pass this on so others won't be fooled into thinking their lead has a broken wire, when it doesn't, and to try and get input to understand what it's purpose is.
This morning, in the parking lot, with the lead reinstalled ('capacitor' removed), I got good reception on a distant FM station and bad reception on 2 locals. Yesterday, 'capacitor' in-line, it was the opposite. Why?

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1986 560SL
2002 Toyota Camry
1993 Lexus

The part probably has failed which is why a signal will not pass through it. It can look ok but still be bad. It is not extremely critical for it to be present and if bypassing it makes it work then by all means remove it. I was only trying to identify the part in question and explain its use. I have seen them used from time to time. Anyway, I am glad it is working fine for you. Alot cheaper than replacing an antenna or cable.

Cleeve Morrison
La Jolla Audio Repair

www.lajollaaudiorepair.com

A capacitor, even one that is good doesn't register continuity with an ohmeter, usually. There are other tests for capacitors, but I don't know what they are . It's placed inline to reduce certain "noise" frequencies, "cleaning" up the signal.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Most likely it's a capacitor. 221 means 220pfd. That's a part value. Read as 22 plus 1 zero in the third digit. Not 22 plus zero. Anyhow, it isn't really necessary, but was there to better match the antenna to the particular radio. It has more effect for AM reception than for FM reception. BTW, had it been a resistor, it would have been painted. A 220 ohm resistor would have been stripped red, red, brown. That's 2,2,1 but read as 220 ohms. Enough of this lecture.

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Resistance is Futile.

Hey, keep the 'lecture' going, I was just beginning to understand! Seriously, thanks to all for clearing up what this is (a capacitor), what rating it is and how to interpret, and its function. I remember now that a capacitor is wired (across/in series with?) the terminals of a tweeter to act as a high-pass filter, so perhaps that's how it works in the antenna, filtering out high frequency 'noise'.

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1986 560SL
2002 Toyota Camry
1993 Lexus