ENIGMA 2000 Newsletter - Issue 29

July 2005
Articles, newsreports and Items of interest :enigma2000-owner@yahoogroups.com

The pa0rdt-Mini-Whip©

A performance report and introduction by mikesndbs for the Enigma 2000 Yahoo group

Roelof, the designer and builder of the Mini-Whip kindly made me one that I have now been able to test. Initially I was surprised at its description and even more surprised when I saw some pictures of it!

This antenna seemed to go against every principle I had learned and accepted.

A whip no longer than 8cm to work at LF and HF, how could this be?

The pa0rdt-Mini-Whip© was designed for NDB use but works all the way up to 30mhz and probably beyond.

The antenna is 8 cm long and the diameter is 3.5 cm.

The actual receiving part is just one square inch of copper clad printed circuit board.

Current draw is 45 mA @ 12 V.

A word of warning! this antenna must be mounted outside. It will not work inside your house. 100 metres or less of good coax is recommended. Also it must be mounted on a non conductive pole!

Anyone wanting to ask further questions may contact Roelof by e-mail to- pa0rdt@amsat.org

Please be aware that at this stage I will not be giving circuit detail as the antenna is now copyright and a publication will soon publish a full report.

So, what does this little beast look like?

size comparison
©Mikendbs220505

The UK coin is a five pence piece for those unfamiliar with this look at the standard BNC connectors to get a idea of the size.

To mount and install the unit I obtained some 400mm white plastic water pipe.

I cut this so that when I mounted it on the eaves of my roof it would hold the mini whip two feet above the roof apex.

This was to allow for strength during high winds.

The whip part of the antenna was placed inside this pipe to protect it further from the weather.

To stop it sliding all the way down the pipe I wrapped some PVC tape around the top cap of the mini whip, that way it was a snug fit when inside the pipe.

Here is a picture of me trying it for size.

©Mikendbs220505

The coax is attached to the whip via a BNC connector, I wrapped self amalgamating tape around this to weather proof it and prevent corrosion, the coax extends down the pipe and then into our house via the loft (roof space).

If you are looking for a very discreet high performance antenna that will work in electrically noisy areas then this antenna may well be what you have been waiting for!

I used a standard TV ‘E’ bracket to mount the pipe to the fascia boards. It is recommended that the braid of the coax be connected to a reliable radio earth before entering the property, however I did not find this necessary at my QTH

inside
©Mikendbs220505

I am holding the plastic 400 mm pipe, the coax is not yet attached to the antenna.

mast
©Mikendbs220505

Here is the finished of.installation viewed from on top of my garage flat roof

Want to see what the antenna looks like inside? Well here you go!

I think you must agree that it would be hard to find a more discreet, light weight antenna for short wave radio listening.

Here are some of the things I have heard with it so far comparing with my ALA1530 loop::

Listening from 09:00 until 09:45 I made the following observations for France.

Call	Fq	miles	Loop	Mini
TA	286.5	186	S3	S6 Audio not as clear as loop
AVD	288.5	299	S2	S6
TH	302.0	194	S3	S6 More noise on whip
AV	306.5	316	S2	S5 Noise again

HOL	315.0	181	S5	S7Could hear another ndb in the background with the mini whip.

VS	317.0	177	S5*	S7 Loop could not hear while whip could!

TY	320.0	266	S4	S6 Best result from whip
ORS	322.0	237	S5	S7* Whip could not hear call
LM	326.0	205	S5	S7
MVC	327.0	141	S6	S8 Could copy with both
AMB	341.0	247	S4	S5 Audio more fuzzy with whip.

Keep in mind that I left the loop set at 150'

Numbers stations received [20/05]

Time	FQ	Station	Signal	Comment
06:00	9388	XP	S9	low audio
06:20	10688	XP	S9
06:40	12088	XP	S9
08:00	8091	E11		calling 232 oblique 00.
12:28	9450	E25
19:34	4880	E10	S8	calling ULX2
20:10	13368	E07		calling 374 000
21:25	9251	E03	S9

It also works wonderfully well on the broadcast bands too!

I have found when comparing the mini whip to my ALA1530 loop that not dependant on frequency at times either will out perform the other, it would seem that these antennas respond to different parts of the radio signal spectrum so that I feel I now have the best chance to catch DX.

Please keep in mind that this file has been prepared for members of this Group to view and should not be reproduced outside of the group.

The owner and maker of the mini whip has requested that details are not published without his authority as a professional publication has first rights to the story!

We thank Mikendbs for writing this piece for ENIGMA 2000 and for Roelof, PA0RDT allowing E2k to use the piece. Note Copyright exists for Designer,Review Author and ENIGMA 2000.

PLondon is also in possession of one of these mini-whips and confirms its good operation.