Larry Benko wrote:
> Darn, I just finished cleaning up the experiment and it is now in the
> trash. I didn't think there were any follow up test to do. I did the
> test at 33% and 66% of the distance from the center and am quite sure
> that doing it at 75% or 80% will result in an even lower resonant
> frequencies with a lower real part to the feedpoint impedance at
> resonance. As far as soldering wires to disks without a hole I really
> believe there would be no change since I soldered a fillet to both sides
> of the disks before. However I will let someone else have a turn with
> this test if anyone wishes. The test could be more easily done with a
> short vertical on a metal plate.
>
Thanks for all the work, Larry
It's nice to see some real testing done on some of these groups.
73
Roger (K8RI)
> Larry, W0QE
>
> Roger wrote:
>
>> pc5m, Carel wrote:
>>
>>
>>> Hi Larry,
>>>
>>> Could you repeat your experiment with a subtle change: don't drill a hole
>>> through the discs but solder/connect the wire on both sides ? I think it
>>> will change your results.
>>>
>>>
>>>
>> One suggestion just to make it interesting...Do as before, but then move
>> the disks out to about 75 or 80% of the wire length from the feed point
>> and run the test again.
>>
>> I'm finding this discourse quite interesting.
>>
>> 73
>>
>> Roger (K8RI)
>>
>>
>>> Carel.
>>>
>>> -----Original Message-----
>>> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
>>> Behalf Of Larry Benko
>>> Sent: Saturday, March 20, 2010 5:21 PM
>>> To: dezrat1242@yahoo.com
>>> Cc: amps@contesting.com
>>> Subject: Re: [Amps] placement of RF choke bypass cap. (Results of
>>> experiment)
>>>
>>> Here are the results of the experiment:
>>>
>>> 1.) Dipole was made with #10 bare copper wire each side 12.0" long.
>>> 2.) Disks are 2.02" diameter x 0.01: thick copper with hole in center
>>> for #10 wire.
>>> 3.) 8ft. of RG-316 coax with 3 common mode chokes (Z>300 ohms at 200
>>> MHz)was calibrated at the far end in order to measure actual dipole feed
>>> point impedance.
>>> 4.) Tests were done in my basement with at dipole height of about 3.5'
>>> and 4-5' of clearance to other objects.
>>>
>>> Test #1: Bare dipole
>>> Fres = 236.20 MHz, Z = 71.5 + j0 (468/length = 234MHz)
>>>
>>> Test #2: Dipole going thru center of disks and soldered with disks
>>> placed 4.0" both sides of the center of the dipole.
>>> Fres = 223.55 MHz, Z = 65.7 + j0
>>>
>>> Test #3: Dipole going thru center of disks and soldered with disks
>>> placed 8.0" both sides of the center of the dipole.
>>> Fres = 199.01 MHz, Z = 44.3 + j0
>>>
>>> Test #4: Dipole soldered to top edge of each disk with disks placed 8.0"
>>> both sides of the center of the dipole.
>>> Fres = 196.89 MHz, Z = 43.9 + j0
>>>
>>> Conclusions:
>>> 1.) The difference in frequency between tests #1 and #2 or #3 and #4 do
>>> NOT allow for the dipole length to be increased by the extra 4" it would
>>> take if the current went around the disks.
>>>
>>> I have pictures if anyone questions my setup etc.
>>>
>>> 73,
>>> Larry, W0QE
>>>
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