Re: [IRCA] [NRC-AM] After Market Radio

[Russ Edmunds <wb2bjh@xxxxxxxxx>]

--- Bill Harms <philcobill@xxxxxxxxxxx> wrote:

> 
> Now I have a couple of questions.
> 
> 1. My truck suffers from really bad ignition noise. It has had this 
> problem since the day I bought it. How do I troubleshoot to get rid
> of 
> this. It varies in intensity with the speed of the engine, so I
> assume 
> it is spark plug related. I have had it tuned several times and each 
> time told them about the problem.  I think the repair guy did not
> quite 
> understand. What should I do?
> 


Sounds like alternator whine or a relative of it. This is fairly
common. You'll need some sort of a whine filter on the power leads to
the radio. Used to use these for VHF ham transceivers back in the
1970's and 80's. The idea is to isolate that whioe and run it to
ground.


> 2. Is there some way to inductively connect an antenna to the whip 
> antenna? I touched the antenna with my hand and it got a little more 
> gain, enough on some of the weaker signals, that they become audible.
> 
> Anyone had experience with that?

Touching the antenna almost always has that effect. Your body is
serving as additional antenna. I seem to recall that at one point Gerry
Thomas ( of Quantum fame ) developed something to do that but I could
be misremembering. One way to attempt such a coupling would be to wind
several turns of common ( insulated ) wire around it to run to the
remote antenna - link coil style. You'd need to experiemnt over a wide
range of number of turns.

> 
> 3. I also have a problem at certain speeds when loud crackling
> noises. 
> It goes away at low speeds.  I suspect it is an antenna shorts or
> open 
> connection.  Any ideas anyone?


Your guesses sound reasonable. My first thought would be the mounting
of the whip itself - possibly the insulation separating the whip from
the truck body is shot.



Russ Edmunds
Blue Bell, PA ( 360' ASL )
[15 mi NNW of Philadelphia]
40:08:45N; 75:16:04W, Grid FN20id
<wb2bjh@xxxxxxxxx>
FM: Yamaha T-80 & Onkyo T-450RDS w/ APS9B @15'
AM: Hammarlund HQ-150 & 4' FET air core loop

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