Friday, December 31, 2010

From blowing snow to freezing rain....time for antenna work to begin...

Over this Christmas break, when the weather seemed to be at it's worst seemed to be the best time for me to get out there and do some antenna erecting and adjusting. For most hams the summer is the best of times..... not for this Tom foolery,  for me the summers are the worst. Now that you think either I have had to much to drink over the Christmas season or I had a bad fall.......my antennas are in the attic of my home. I set up a 20 meter dipole last summer when it was about 80 or more outside. Well in the attic it was way over 120 degrees so the cooler weather along with either snow or freezing rain does not matter to me.....BRING IT ON!!!

20 meter dipole with 1:1 balun
For some time now I have been listening to 20 meters close down very early and 40 open up. I have no 40 meter antenna (other than my High Sierra sidekick that requires setup outside at my deck)  I did lots of looking for a 40 meter antenna most dipoles were just to long. The antennas I considered were the MFJ 1788  it's a great antenna coverage from 15 to 40 but at 560.00 a little to steep at this time. I looked at the Par Endfedz but the owner did not recommend this antenna for going in the attic. I also looked at some folded dipole setups but with the way the rafters were configured along with the 20 meter dipole up there already it just would not work. The B&W folded 40 meter dipole seemed promising but the price of 450.00 with shipping and tax I would be better off getting the MFJ 1788 as it also had more coverage.  It then occurred to me that I do have a 40 meter mobile whip antenna from Valour Pro am These antennas are reasonable at 30.00  if I was to pick up another antenna along with the right mount I could set up a 40 meter dipole.
Wooden base support for 40 meter dipole
New 40 meter dipole ready to have SWR fine tuned
Sure this is a compromise antenna but it works for the attic size that I have and it does get me on 40 meters. After searching I found the mount at a local ham store called the RVD HD mount. These antennas boast of a 40 khz band width on 40 meters and if I need more than that I have the tuner in the Elecraft K3 radio. So the project began over the holidays I used a wooden base screwed to the joists in the attic and a wooden broom handle that was lying around in the basement as a mast. I had some LMR-400 coax that I ran up to the antenna. Now it was time to tune the antenna, one of the best investments I have made for antenna work is my MFJ-259B antenna analyzer. This little unit makes antenna tuning a snap you may not use it all the time but when needed it makes antenna tuning a happy experience.  Also for the least amount of trips into the attic to tune the antenna the better. The SWR at 7.030.00 is 1.2:1, 1.3:1 at 7.000 and 1.5:1 at 7.070. Not bad at all for an attic dipole!!
Close up showing balun and bracket
Discone D130-J
While I was up in the attic and tuning antennas I wanted to also fine tune the 20 meter dipole. This dipole is the Hy-Gain 18TD it's like two metal tape measures held together in a plastic case. On one side of the case you have the measurements for each band up to 80 meters. You wind the tape out to the desired lenght and there is your dipole. Hy-Gain does not sell this unit anymore and I have had mine for over 25 years. This antenna went up last summer during the heat and the best SWR with the recommended measurements was 1.7:1 and up. Now it was time to fine tune this dipole and I was able to get in down to 1.2:1. So now Im on 40 meters and also a better SWR on 20 as well. I have had some spare time to try out the new 40 meter dipole using 5 watts. During the evening of the 29th I contacted K1YS in Massachusetts. The next evening a short QSO due to QRM with W2XS just down the way in Northport New York John was only running 1 watt. Later on that evening a long QSO with K2JY also in New York State Steve was using the FT-817 at 5 watts. No big DX as of yet but I am on 40 meters and the DX will come. Finally I tossed in a picture of my last antenna the Diamond  D130-J I have my Yaesu VX-6R hooked up to it. The Discone receive converge is from 25 to 1300 Mhz and transmit is 6m, 2m, 70cm, 23cm and 33cm.

10 comments:

  1. Happy New Year Mike, nice post and enjoyed reading about your 'stealth' antennas.

    Bob VE3MPG

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  2. Thanks Bob, I'm very happy they way they preform being up in the attic and only 5 watts output.

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  3. Hi Mike, Happy New year to you, yes the analyzer is a great piece of kit, I wouldn't be without mine, since I have built my dipole for 40m, the band has come alive, from here in the UK from 2200 GMT N. America and S. America come alive, so I'll listen out for you !

    Had you thought about building a trapped dipole for perhaps 40 and 20m, that might fit ?

    73 Paul.

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  4. Happy New Year to you as well Paul, I was thinking about putting together a 20/40 trap dipole but the time constraints over the holidays would not allow me the time to get it done and up.

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  5. Hi Mike, all the best in 2011. Looking at the pictures I was surprised by all the antennas you made in such a small space. Actually I was evenmore surprised by the construction of the attic itself. Of course it is not a real floor in the house...I hope you make some DX on 40m. 73, Bas

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  6. Good morning Bas and Happy New Year to you, yes this attic construction is very common here in Canada. If you want to use your attic for anything (other than antennas) some construction would have to take place. In most homes the attic is just an off limits place as most "stuff" is stored in the basements some even load up the garage as well.

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  7. Mike, your attic reminds me of my own, and especially that photo of the discone because I have a discone just like that which I first had in the attic a number of years ago. I have a listening wire in the attic but have recently contemplated some sort of mini trap dipole for emergencies just in case. I did not know you were a QRP operator. If I ever run an antenna in the attic I will put max 10 watts through it. I have RFI issues at times with some of the neighbours here which is always a drag. Anyway, best wishes with the experiments. Let me know if you get any decent DX on 40 metres! 73 de EI2KC Anthony

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  8. I like the new template Mike - much easier to read.

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  9. Hi Anthony, I keep my signal QRP for that very reason not wanting to let anyone know I have a ham setup via RFI.

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  10. Good morning John, I figured it was a new year so also time for a new template and good to see that the blog is easier to read.

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