[MRCA] Moose Net Tuesday

[B. Smith]

Whew!  It would have taken my 2 hours to write this this us. Good job Al.


On 9/10/2013 4:37 PM, Al Klase wrote:
> Hi Alex,
>
> The idea is to put a small capacitance in series with a random-wire 
> antenna to move it's impedance to a place that make the tuner in the 
> rig happier.
>
> For example, a rig designed to tune a short whip if always going to be 
> looking for a capacitive load, as the antenna is usually less than a 
> quarter wavelength, and thus look like a capacitor in series with the 
> antenna's radiation resistance.
> .
> If the wire in use is longer than a quarter wave say by 20 or 30% it 
> will look inductive.  Putting a cap in series can make the total 
> impedance capacitive, and allow the rig to tune it.
>
> I was hoping I could find my box for a photo op, but no.  It's a small 
> plastic box with three 5-way binding posts and a 100 pf and 50 pF 
> high-voltage "doorknob" inside in series.  You can easily choose 50, 
> 100, or 150 (in parallel) or 33 pF (in series).  Caps should be HV 
> types as the RF voltage can get pretty astronomical even with 20 watts.
>
> The long-wire adapter for the PRC-1099 is just such a device, not 
> variable however.
>
> This is a matter of cut and try for most of us.  For possible 
> enlightenment Google "conguate match" and "smith chart." Imaginary 
> numbers give me nightmares, however.
>
> Regards,
> Al
>
> On 9/10/2013 2:55 PM, Alex J Rokowetz wrote:
>> Breck,
>>
>> I am not afraid to admit when I do not know something and I will 
>> readily admit that I know way less than most of folks on this email 
>> reflector.
>>
>> Would you be so kind as to briefly outline what I would do with these 
>> capacitors or point me to a online or print resource to help me learn 
>> more.  I searched online but did not find something useful.
>>
>> Thanks,
>> Alex
>> K2AJR
>>
>> P.S. Thanks for the signal report about KW2K's transmission!  She was 
>> operating the TW7000F with the remote autotuner and a 65' wire up 
>> into the tree.
>>
>> ------------------------------------------------------------------------
>> *From:* B. Smith <smithab11 at comcast.net>
>> *To:* mrca at mailman.qth.net
>> *Sent:* Tuesday, September 10, 2013 12:57 PM
>> *Subject:* [MRCA] Moose Net Tuesday
>>
>> Interesting band  conditions, Heard all stations, copied Yuki KW2K
>> louder than I have before. Fun watching Al on video trying to get that
>> PRC-104 to tune.
>>
>> K4CHE antenna hint for the day: Put several fixed caps(25, 50, 100 pf or
>> a variable) in your antenna bag and use them either in series or in
>> parallel for that random wire antenna.
>>
>> Z
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>
> -- 
> Al Klase - N3FRQ
> Jersey City, NJ
> http://www.skywaves.ar88.net/
>
>
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