Topic: Radio noise suppression, 6 volt AM


fsacht    -- 03-05-2012 @ 4:05 PM
  Question:
Ford recommends noise suppression condensors at a number of locations to eliminate/reduce static and hum in the original 6V tube type radios. Haven't checked if Drake, C&G or others supply original or correct condensors. Can we use, say an ignition condensor at any of the recommended locations and achieve the desired results or is there a specific capacity required for results?


TomO    -- 03-06-2012 @ 8:06 AM
  Before you invest in capacitors to reduce the noise in your radio, check that the antenna lead-in shield is grounded at the body and at the radio. If the shield is open, you will have a lot of static and ignition noise.

The capacitors are only needed when the stations are weak. An ignition capacitor is the wrong value for noise suppression. Do not buy NOS Ford filter capacitors. They may break down shortly after installation.

Please provide the year of the car in your post, that you have a question about .

Tom


supereal    -- 03-06-2012 @ 9:18 AM
  Most, if not all, radio "noise" is ignition related, and condensers on the generator, etc, seldom reduce it. The problem is most evident on the AM band. That is why many of us have had our original radios converted to AM/FM, while retaining the original appearance. Follow Tom's good advice regarding the antenna connections, particularly concerning the grounding at the base. Paint and rust prevent contact, so the shield, itself, can become an antenna for static. Locate and adjust the antenna "trimmer". It is usually behind the tuning knob or near the antenna jack on the radio chassis. Tune the radio to a weak station somewhere above the middle of the dial, and tweak the trimmer for the loudest and clearest signal. The AM band will always have lots of noise, compared to modern car radios, unless you are almost within sight of the radio towers, because of poor shielding of the tube components. It was such a problem with the early Corvettes and their fiberglass bodies, that the whole ignition system had to be fitted with a metal cover.

This message was edited by supereal on 3-6-12 @ 9:22 AM


fsacht    -- 03-06-2012 @ 4:31 PM
  The radio is a Zenith AM original radio in a 42 Mercury. The antenna is right cowl top mount. Tom, how does one check to determine if the antenna lead-in shield is grounded at the body and at the radio? What exactly is the antenna lead-in shield? Another interesting phenomenon is that with the car at rest the volume is acceptable. With the car in motion the volume reduces noticeably.


supereal    -- 03-06-2012 @ 8:17 PM
  To check the base ground of the antenna, pull the lead out of the receiver jack and connect an ohmmeter between the shield and a known good ground with the meter set on the 1X scale. The needle should swing all the way over.. As for noise, most old cars have enough interior noise to make the radio sound weak. I have a convertible, and it is so noisy, the radio is useless when on the road.


TomO    -- 03-07-2012 @ 8:16 AM
  In addition to Superreals advice, check the cowl mounting to make sure that the star washer is against the inside of the cowl and that the nut securing the antenna is tight. You should not be able to move the antenna base with out using a lot of force.

If the shield is not grounded, it will also affect the volume as well as providing a source for the noise to enter the radio. The shield is the braided outer part of the lead in. The radio needs a good ground also. It is grounded through the mounting bolts.

Tom


fsacht    -- 03-07-2012 @ 2:42 PM
  The shield is well grounded. Antenna base is tight to cowl top and radio secure. The antenna mast is fixed length. Clipped a length of wire to the tip of the mast adding some antenna length and retrimmed the antenna pot. Much improved. Think it's time to buy a better antenna.
Thanks for the direction.


Old Henry    -- 03-07-2012 @ 10:33 PM
  I have a cowel top mounted antennae on my '47 that's probably about the same as yours except that mine is a telescoping one that's 18" at the shortest and I extend it to 31" to just clear my garage door. That extra 13" makes a lot of difference in volume and noise reduction so I think you're on the right track to get something like that for yours. Here's one like mine on ebay for $50.00 (except it has a red ball on the end - don't know what that's about - 'course I ran a Union 76 orange ball on mine for a while). http://www.ebay.com/itm/1947-54-Mopar-GM-FORD-Red-Ball-tip-Radio-antenna-NORS-/370570732683?pt=Vintage_Car_Truck_Parts_Accessories&hash=item5647bca48b&vxp=mtr

Old Henry
(The older I get, the better old looks.)

This message was edited by Old Henry on 3-7-12 @ 10:45 PM


fsacht    -- 03-08-2012 @ 1:08 PM
  Old Henry
Thanks for your lead. I ordered a cowl mounted antenna, 6A-18813 from C&G Early Ford Parts earlier this morning. Thanks once again.


Old Henry    -- 03-08-2012 @ 8:22 PM
  Hope it helps. Let us know.

Old Henry
(The older I get, the better old looks.)


EFV-8 Club Forum : https://www.earlyfordv8.org/forum
Topic: https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=4410