[Lowfer] thoughts on PA0RDT "mini whip"

n8tl n8tl at woh.rr.com
Thu Dec 22 10:11:30 EST 2016 

Further to last message, the probe is used for both MF, LF, and VLF 
work. Since the Icom IC-R75 cuts off at 30 Khz,  I can transfer the 
co-ax/isolation transformer from the R75 directly to the Asus Zonar 
Essence II sound card line input for receive work below 30 Khz.  I then 
use spectrum lab vlf programs to receive below 30 Khz.  A neat little 
setup for LowFer work and condo living.

Tom N8TL





On 2016-12-22 09:46 AM, Douglas Williams wrote:
> Tom, that sounds like a great setup. How did you weatherproof the coax
> connection at the antenna base where you attached the grounding point?
>
> On Thu, Dec 22, 2016 at 9:44 AM, Douglas Williams <
> williamsdoug1966 at gmail.com> wrote:
>
>> Same here, Jack. I have a 90% completed AMRAD whip that I just need to
>> seal in PVC pipe and attach the connectors.....
>>
>> On Thu, Dec 22, 2016 at 9:41 AM, Zack Widup <w9sz.zack at gmail.com> wrote:
>>
>>> Any idea how it does compared with the AMRAD e-probe antenna? I built an
>>> AMRAD whip but have yet to put it up. Since I have the next week off from
>>> work and it might be unseasonably warm, this is probably a good time to do
>>> it.
>>>
>>> 73, Zack W9SZ
>>>
>>>
>>> On Wed, Dec 21, 2016 at 4:50 PM, Howell, Laurence J <
>>> L.Howell at conocophillips.com> wrote:
>>>
>>>> Doug, I have three or four probes up various trees, some just separated
>>> by
>>>> 5m or so, but as ever, the selection of the height and location sweet
>>> spot
>>>> for best s/n is manifestly important here. A few feet either way can
>>> make a
>>>> hooge (hooge) difference  - I ve run various shoot outs on what works
>>> best
>>>> and though we get the odd earlier long haul decode on 475 with the
>>> highest
>>>> probe (50ft or so), the best here is one at around 35ft or so called
>>> "Aces
>>>> high" - slightly higher than RDT states but I do see that curve too in
>>> s/n
>>>> using NDB and W&G test set.
>>>>
>>>>   It took me a season or two to get just the right tree. Out of all the
>>>> antennae here the probes tend to work best over active or passive large
>>> or
>>>> small loops but that's probably because of the bespoke nature of the E/M
>>>> interference fields on this acre and related to off site man made
>>>> electrical noise sources. It will be different elsewhere - what works
>>> best
>>>> here wont elsewhere.
>>>>
>>>> I figured out that the best type of tree to have one on is the Genus
>>>> "Acacia" - which is pan-global and typically the worse is the Coconut
>>> Palm.
>>>> I see a lot of comments on they are just mickey mouse appliance antenna
>>>> but Ive been using them in military and commercial situations for over
>>> 35
>>>> years and its horses for courses, and they work best here (and in a lot
>>> of
>>>> other countries around the globe) over anything else. Stat. Used to use
>>>> them in Antarctic for air-to-ground ops when the main wideband or LPA
>>> were
>>>> snow static bound....
>>>>
>>>> I ground the RG6 where it typically hits ground (boggy ground into a
>>> lake
>>>> typically), large series J common mode choke at that end, another in the
>>>> shack, keeping the power injector away from noisy mag fields that
>>> intrude
>>>> even metal ali boxes, then Bino isolated transformer which is usable at
>>>> 1kHz up to 500kHz or more - quite a few turns on 73 material from
>>> memory.
>>>> Power is battery though simple unstab DC from 110VAC is pretty good if
>>> you
>>>> decouple well. Playing with the voltage from 9-18VDC can help with iMod
>>> -
>>>> mine appears happy around 15V but my local blow torch on 1430kHz
>>> appears to
>>>> have a issue with pins stuck in its coax quite often :-) (joking)
>>>>
>>>>
>>>> Laurence KL7L
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Lowfer [mailto:lowfer-bounces at mailman.qth.net] On Behalf Of N8OOU
>>>> Sent: Wednesday, December 21, 2016 1:32 PM
>>>> To: Discussion of the Lowfer (US, European, & UK) and MedFer bands <
>>>> lowfer at mailman.qth.net>
>>>> Subject: [EXTERNAL]Re: [Lowfer] thoughts on PA0RDT "mini whip"
>>>>
>>>> Doug,
>>>>
>>>> The mini whip is mounted and grounded to the top of a galvanized steel
>>>> trellis that I grow hops on. The trellis is about 15 feet tall, and
>>>> grounded at the base. RG-6 quad shield coax is grounded at the mini
>>>> whip/trellis, and runs back to the shack. Nothing in the shack is
>>>> externally grounded. I'm not sure if the DC power supplies ground back
>>>> to the mains.
>>>>
>>>> 73   de   N8OOU - Mike Meek
>>>>
>>>> On 12/21/2016 03:55 PM, Douglas Williams wrote:
>>>>> Mitch & Mike,
>>>>>
>>>>> Thanks for the info.
>>>>>
>>>>> Mike, did you ground the antenna at the base, halfway point, or at the
>>>>> house?
>>>>>
>>>>> Anyone else have any info, feel free to chime in.
>>>>>
>>>>> D. KB4OER
>>>>>
>>>>> On Wed, Dec 21, 2016 at 4:48 PM, N8OOU <n8oou at meekfarm.us> wrote:
>>>>>
>>>>>> Doug,
>>>>>>
>>>>>> A few observations on the mini whip.  I built one from my junk box
>>> parts
>>>>>> based on the original design. I had to add a notch filter to block my
>>>> local
>>>>>> 500W AM BCB station. Inserted in the whip between the FET and Buffer
>>>> amp. I
>>>>>> also must use a 500 Khz low pass filter at the receiver for LF. I
>>> have
>>>> it
>>>>>> mounted about 15 Ft above ground, away from the house, and grounded
>>>>>> according to common information found on the web.
>>>>>>
>>>>>> It works (all the way up to 10m), better than a long random wire, but
>>>> not
>>>>>> as good as the Low Noise Vertical I just finished.
>>>>>>
>>>>>> 73   de   N8OOU - Mike Meek
>>>>>>
>>>>>>
>>>>>> On 12/21/2016 03:07 PM, Douglas Williams wrote:
>>>>>>
>>>>>>> Have any of you used one of these on VLF/LF? What are your
>>> experiences?
>>>>>>> They seem to be everywhere on eBay, from kits to fully assembled,
>>> and
>>>>>>> averaging $12 - $40.
>>>>>>>
>>>>>>> D. KB4OER
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