Topband: MA160V and Pro III for topband

[Bryon PAUL Veal n0ah]

Finally, with some empirical data, I guess you can consider this the concluding post on our MA160 vertical set up. 

After building the Cushcraft MA160V, I did a few more things to get ready for the contest.  First, I removed the Alpha Delta B 55 foot 30-160M sloper which ran from the tower and tied off 20 feet from the vertical. In doing so, the coupling effect removed was a narrower bandwidth and higher resonant point. Using the Amidon UnUn, I went from 1.6 to a :1.9 SWR and the resonant point dropped from 1.822 to 1.818MHz.  Very touchy antenna- 

As a result,I went from having 25Khz to 15Khz of 3:1 bandwidth.  So some of the antenna modeling I researched on Topband about what the antenna BW and resonant point would do with a decent radial field proved true.  Without the UnUn, my true SWR at resonance was 3.2:1.  This was measured using the MFJ 259B analyzer. 

With the Dentron Tuner, I was able to get about 80KHz of very flat 1:1 tuning space but with some difficulty.  Obviously, the antenna has a very high Q with a decent radial field. I now have 28 buried radials averaging 50 feet. I also took a long radial and attached it to the MA80/40 vertical’s radial field centered 60 feet away.  I took the MA80/40V down as it was very close to the K9AY rx loop for the contest with four 20 foot radials under each loop. 

MY Pro III auto tuner could tune from 1.802-1.830MHz- The K9AY loop, going east and west with a single loop, was used for receive in most cases. However, the  KL7 and KH6 were worked just the vertical, as was the case when I worked ZL8X the second time. I didn’t realize I was in their log for 160M during CQWWCW and worked them again the next morning before I saw myself in their on-line log. The second time I worked them, it was a very clean exchange.  The first time was in the middle of all the QRM in CQWWCW. At the time, I wrote out the card but didn’t correct my log until later. 

I have read a lot on the best rig for topband.  Personally, I am very pleased with the Pro III as a little pistol sitting in the middle of the crowed suburbs. The filtering and noise reduction circuit works very well for picking out very undetectable signals at first.  Mostly, weak stations and/or very far away DX.  I have thought about adding the INRAD filters but yet.  Our goal before the contest was 500 QSO’s and WAS and we ended up with a much better score and just fell three sections short, PR, NL, and NWT, for a clean sweep so to say- I was not looking for EU’s or JA’s but we did manage to work 6 DXCC stations, mostly XE and the Caribbean.  Some of the big guns around here had some awesome runs with EU and JA.......We built the station in mind for competing in stateside topband contest. A few posts over the years mention the MA160V as being no better than a car antenna for the band. But I think it does a lot better-    

N0AH 2010 ARRL CW stats:

Icom Pro III,  Cushcraft MA160V,   K9AY single loop,  100 watts

QSO’s: 532, Sections 82, DX 5 unofficial score=88,724

Districts                           Leading Section
W-1  3.8%                        8 NH
W-2  3.0%                        7 WNY
W-3  2.4%                        4 DE, EPA, MDC  tied
W-4  11.5%                       16 VA
W-5  14.1%                       22 NTX
W-6  8.6%                         15 SV   conditions to W6 just really never opened up for the expected morning runs- but others have reported similar results- 
W-7  14.3%                       21 AZ
W-8  5.8%                         15 OH
W-9  8.6%                         20 IL
W-0  21.8%                       41 MN
VE     4.5%                         7 AB, ON  tied
DX     1.1%                         2 C6

I missed the first three hours both nights from 3-6 p.m.. Didn’t get started until 8 pm the second night. I think we would have had a much better score- This is not so much a contest post, but I am using contest figures to show that this antenna performs well, compared to expectations of some older posts on Topband based upon modeling.  I hope to encourage those of you with small backyards not on topband yet, or like us, previously with a shortened wire antenna, to consider this set up.  That is the motivation behind this post- Hope this helps- 


73  Paul  N0AH