[R-390] image

[Bob Camp]

Hi

If the neon bulb is glowing you have over 70 volts on the antenna  
terminals. If that's the case, the radio is a bit overloaded ...

The neon bulb is mostly there to protect the input capacitors against  
static induced voltages on a whip antenna.

Bob


On Oct 22, 2007, at 6:37 PM, Jim M. wrote:

> Both of my 390as have had that neon lamp removed by someone before  
> I got
> them.  It would be interesting to look at the lamp to see if it is  
> glowing
> from the big BCST signal down the road.
>
> -----Original Message-----
> From: rbethman [mailto:rbethman at comcast.net]
> Sent: Monday, October 22, 2007 4:58 PM
> To: jmiller1706 at cfl.rr.com
> Cc: Joel Richey; r-390 at mailman.qth.net
> Subject: Re: [R-390] image
>
> Folks,
>
> DO NOT simply try and unthread THAT neon bulb!  It is soldered in - at
> least in EVERY R-390A that I've come across!!
>
> Its purpose IS to take excess energy on the antenna to ground.  A
> perfect example is the "sand" in the Middle East.
>
> When it blows around, the static goes sky high.  That took out the  
> front
> ends in the Harris rigs in the First Dessert Storm.
>
> Bob - N0DGN
>
> jmiller1706 at cfl.rr.com wrote:
>> There is an antenna overload lamp (I-103) inside the antenna relay  
>> that
> illuminates in some fashion when a strong nearby signal is  
> present...to
> protect the front end presumably.  This is an NE-45 (neon type?).   
> If a neon
> bulb is triggered by a very strong signal, what kinds of harmonic- 
> producing
> non-linearities would it inject into the front end?  Open the  
> antenna relay
> andremove the bulb (if it's there) and see what happens.
>>
>> More food for thought.
>>
>> ---- Joel Richey <richey2 at mindspring.com> wrote:
>>
>>> Hey, whats going on, 4 hours and no talk of images, I think its  
>>> alien
> intervention, we need to get Fox mulder from the X-files to check  
> this out,
> there more here then meets the eye.
>>>
>>> Joe W2DBO
>>>
>>
>
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