[Milsurplus] ARB Antenna capacitor

[W2HX]

So for us less-initiated... what is "suckout?" Sounds very technical ;) 

 
73 Eugene W2HX
 


-----Original Message-----
From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Hue Miller
Sent: Monday, December 09, 2013 1:17 PM
To: milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] ARB Antenna capacitor

Yes, i think that's along the lines of what i was thinking. WIth all the 

additional capacitance to ground otherwise seen right at the ARB 

antenna.

-Hue
 

> From: n4fs at eozinc.com
> To: kargo_cult at msn.com; milsurplus at mailman.qth.net
> Subject: RE: [Milsurplus] ARB Antenna capacitor
> Date: Mon, 9 Dec 2013 09:41:21 -0500
> 
> What about simply, minimizing the effects of "suckout". 73 - Mike
> 
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
> 
> -----Original Message-----
> From: milsurplus-bounces at mailman.qth.net
> [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Hue Miller
> Sent: Monday, December 09, 2013 12:09 AM
> To: milsurplus at mailman.qth.net
> Subject: Re: [Milsurplus] ARB Antenna capacitor
> 
> My thinking was that this condenser would have minimal effect in 
> attenuating stray oscillator inputs. I was thinking that the overall 
> antenna capacity as seen by the ARB with multiple receivers connected 
> plus the circuit through the ATC might be deemed ?too? far off the 
> design "standard" capacity. A condenser of 36pF would pretty well 
> define that antenna capacity, since it is a multiple lower than would be seen by the rest of the outboard wiring.
> Would a high capacity at the ARB antenna post detune the antenna's 
> resonant circuit? I do not know. More wisdom (more inputs from others) is required.
> The impedance of the 36pF at 4495 kcs (for example :) is about 1000 ohms.
> Yes, that would make for a filter effect, considering the low 
> impedance of the ARB input circuit to off-resonance frequencies. 
> However for stray oscillator inputs at the same frequency the ARB is 
> receiving, 1000 ohms, I think, is like, forgettable, considering the ARB input impedance.
> It was worth the question for me to learn that this was not a hammy mod.
> I believe I first saw it in a surplus store where most of the avionics 
> of some plane had showed up, ARB, ATC, and who knows what else.
> -Hue
> 
> -----Original Message-----
> From: Mike Hanz
> Sent: Sunday, December 08, 2013 8:34 PM
> To: Hue Miller ; milsurplus at mailman.qth.net
> Subject: Re: [Milsurplus] ARB Antenna capacitor
> 
> On 12/8/2013 7:02 PM, Hue Miller wrote:
> > So the series capacitor was to somehow discriminate against, how? ( 
> > Not getting it. ) And not to diminish the total antenna capacity, 
> > nor to somehow protect the receiver?
> 
> Why would one want to decrease the antenna capacity seen from an ARB's 
> perspective, Hue? I haven't found the mica transmitting cap on the ARB 
> antenna input used in any other system other than where multiple 
> receivers were attached to a common receive antenna. That should tell 
> you something about its deployment. What we do know is that it is 
> possible to reduce interaction through de facto bandpass filters, 
> using inherent set antenna input capacities and inductances. What we 
> do not know at the moment is whether the intent was to diminish 
> interference from the ARB or the command sets. Further research is needed.
> 
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