[MRCA] Moose Net Tuesday

[Al Klase]

Yeah, but I wish I could proofread better.  It's technically ok, but 
slightly illiterate.  Probably written by an en-geneer. - Al

On 9/10/2013 5:04 PM, B. Smith wrote:
> 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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>
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-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/

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