[Elecraft] KXAT2: Recommended Random Wire Lengths

Sun Jan 29 16:18:18 EST 2017

Hi Jim, 

Thanks for this. Lol, I worked for HP and spent a lot of time in Roseville in your ‘winter’ months. Our current winter weather limits outside antenna experimentation for the very ambitious or a desperate ‘wire down’ situation.

I too was giving serious thought to a vertical wire on a telescoping pole just as you describe and leaving the CrankIR home. Seeing a local ham who has become well practiced with QRP CW/digimode field deployments has the MFJ telescoping pole to hold up an end fed wire in an inverted vee with a home brew 9:1 and a LDG Z100 tuner.  He’s quite happy with it so this is definitely on my list of things to try. 

I seem to remember hearing the design intent of the KX2/KX3 ATU’s were such that a 9:1 Balun is not required. I think I was told that in person by one of the Elecraft principles at Dayton then read it somewhere as well. Unfortunately I’ve not put that to the test myself but I may just brave the cold before the trip long enough to test it out. 

So I guess a good question is...does the 9:1 balun produce better results then simply connecting direct to a KX2/3 ATU?

Since I’ve usually been able to build or buy resonant antennas over the years so I must confess I’ve not had that much experience with tuners..other then using a friends summer cottage G5RV or touching up the band edges of a narrower antenna. For the trip I expect never to go lower in frequency then 40meters given the southern latitude and I’ll only be operating between lunch and supper barefoot (in bare feet) one or two afternoons max. 

The your trip to the Philippines sound exciting! You have to let us know when you are there set up so we can try and work you.

Brian ve3bwp

> On Jan 29, 2017, at 12:25 PM, James Bennett <w6jhb at me.com> wrote:
> 
> Hi Brian,
> 
> I’ve also got a KX3 and use it in the summer on the back patio and occasionally from the family room when it is not sitting on my shack desk, tethered to the KXPA100. When I do those “portable” operations I use an end-fed vertical that I came across at the web site of EARC - the Emergency Amateur Radio Club in Honolulu. URL below. Very simple antenna - is uses a 30 or so length of wire strung vertically and a 9:1 un-un. I homebrewed the un-un - piece of cake.
> 
> While it isn’t the same as a super long wire antenna up 80 feet, it does pretty darn well. In fact, I will be taking my KX3 (barefoot) and this antenna on a three week vacation this spring to the southern Philippines - Mindanao. No (or very little) SSB, but primarily CW and possibly digital modes.
> 
> Easy to build or cheap to buy, lightweight to transport, and performs very well...
> 
> Here is the address of the EARC: 
> 
> http://www.earchi.org/92011endfedfiles/Endfed6_40.pdf <http://www.earchi.org/92011endfedfiles/Endfed6_40.pdf>
> 
> Jim Bennett / W6JHB
> Folsom, CA
> 
> On Jan 29, 2017, at 9:12 AM, Brian “VE3BWP” Pietrzyk <ve3bwp at gmail.com <mailto:ve3bwp at gmail.com>> wrote:
>> 
>> Hi Murphy, your post comes at a good time for me. Thanks for this info. I'm preparing to take my new KX3 to the Dominican Republic next month for a QRP deployment on the beach at a resort. I'm planning to do WSPR, JT65, PSK31 and PHONE. I've not kept up my CW so I'm hoping to try some fldigi assisted CW contacts although it doesn't seem to copy human sent code very well so we'll see how that goes. 
>> 
>> I've tried a couple of other (Phone only) Caribbean QRP deployments when I had my FT817 and ATAS 25. 3 years ago in Panama it was winter field day and 10m was open so I created a pileup. It was a blast and I was bitten by the bug! (If you search ve3bwp QRP Costa Rica on YouTube you can see a few of the reactions I got - intrigued, the hotel staff kept the Marquita's flowing so I may sound a bit tipsy). 
>> 
>> Then last year I tried It from Panama. Didn't_make_a_single_contact! Heard lots but no-one heard me. I realized how ill prepared I was and relying on a compromise antenna near a solar minimum (with no CW or digimodes) would be even that close to the equator. 
>> 
>> So this year with a new KX3 and my wife's super thin MacBook life I'm going getting serious and I have a proper antenna! I've started reading through the Elecraft message archives trying to find all random wire success stories. I got some of the Wireman silky wire and now in search of what lengths to try. I saw Wayne's recommendation for 25ft for 40-6m so I've cut some for that. I'm looking to precut a few different lengths to try for various band combinations. Maybe even some band specific resonant ones for 20 to 10m so if anyone has some tried and true lengths for those I would appreciate hearing about actual lengths. This will be my first time with end feds or random wires. I'm also giving serious thought to packing my CrankIR as it can be made resonant very easily but it's 13.5lbs and would be the heaviest and bulkiest item of all. I may take it though just in case since it is comparable in performance to my base dipole. With it I've had regular phone ragchews at 5w with 
>> many assuming I was running way more power. 
>> 
>> Anyway if others have has similar ambitions/successes... would love to hear about it. 
>> 
>> Thanks and regards,
>> 
>> Brian ve3bwp
>> 
>>> Message: 19
>>> Date: Sat, 28 Jan 2017 16:30:57 -0500
>>> From: murphy <mac3iii at gmail.com <mailto:mac3iii at gmail.com>>
>>> To: elecraft at mailman.qth.net <mailto:elecraft at mailman.qth.net>
>>> Subject: [Elecraft] KXAT2: Recommended Random Wire Lengths
>>> Message-ID: <cb8ba97a-f144-d077-e73f-935230939990 at gmail.com <mailto:cb8ba97a-f144-d077-e73f-935230939990 at gmail.com>>
>>> Content-Type: text/plain; charset=utf-8
>>> 
>>> I love my new KX2 and the installed auto-tuner.  The manual mentions a
>>> random wire antenna with a counterpoise and recommends #26 ?Silky? from
>>> The Wireman (catalog #534).  After obtaining 100 feet the first question
>>> is how long?  Obviously I want it to tune 1:1 SWR, 80 to 10 meters but a
>>> quick search of the archives and manual came up dry for specific random
>>> wire lengths.  So I cut 29 feet x 2 and boom - no joy.  The 5MHz band
>>> got no better than 4:1 SWR and 80 meters was, well, hopeless.  The rest
>>> was good.  Ok searching the net the best I could find was
>>> http://www.hamuniverse.com/randomwireantennalengths.html <http://www.hamuniverse.com/randomwireantennalengths.html> with the magic
>>> number lengths: *29  35.5  41  58  71  84  107  119  148  203  347  407 
>>> 423*.  Still, no guarantee which would meet requirements on the
>>> KX2/KXAT2.  So, after a splice and another cut, I can now officially
>>> announce that a 58 foot "random" wire with a 29 foot counterpoise will
>>> give a 1:1 SWR on all bands 80-10 on the KX2 using the KXAT2. :-)
>>> 
>>> Message: 26
>>> Date: Sun, 29 Jan 2017 02:38:20 +0100
>>> From: "Emory Schley" <silverlocks at gmx.com <mailto:silverlocks at gmx.com>>
>>> To: Elecraft <Elecraft at mailman.qth.net <mailto:Elecraft at mailman.qth.net>>
>>> Subject: [Elecraft] Random wire lengths for antennas
>>> Message-ID:
>>>   <trinity-d32bc86b-748e-42a8-bde9-d162f4e183b0-1485653900435 at 3capp-mailcom-bs04>
>>> 
>>> Content-Type: text/plain; charset=UTF-8
>>> 
>>> My KX2 Owner's Manual, page 10, says "A length of about 25 feet for each wire, matched to the KX2's output using an antenna tuner (see ATU, pg. 11) will typically provide good performance on 40-10 m. (Without an ATU, resonant lengths are required for each band.) This antenna is ideal for outings where all gear must fit into a small bag (e.g., our model CS-40)."
>>> 
>>> I just bought my KX2 in late November/December 2016, so I presume this is the latest edition of the Owner's Manual.
>>> ?
>>> Emory Schley
>>> N4L
>>> 
>>> 