Starting a new yagi today

[RickC.]

Thanks for the kind words-- between the weather and work stuff I have had all KINDS of delays with this project. I'm just about to start hauling stuff upstairs as soon as I drink this Diet Pepsi, and will have the coax run up through the modified soffit vent before dark. If 20 is open at all I should be able to run it through at least a few paces tonight.

Sorry if this has gotten boring because it's dragged on for so long!


Rick

 

[Robb]

Thanks for the kind words-- between the weather and work stuff I have had all KINDS of delays with this project. I'm just about to start hauling stuff upstairs as soon as I drink this Diet Pepsi, and will have the coax run up through the modified soffit vent before dark. If 20 is open at all I should be able to run it through at least a few paces tonight.

Sorry if this has gotten boring because it's dragged on for so long!


Rick

It's been a white-knuckle read so far. Very Cool. I'd like to see the final design after all of your adjustments. If possible, perhaps even a materials list, since you did substitute some original parts.

Looks great!

 

[RickC.]

Well, dammit.

Ain't gonna happen tonight. The pitch of the roof is such that I can't get to the coax coming up through the soffit, so I'm gonna have to come up with plan C or D to get the feedlines into the house. I've been doing this since the early 70s and have never had so much trouble with this issue.

&!*!!$@!

 

[HomerBB]

I used to install security systems where the problem you face was an everyday occurrence. What you need is a fish tape. It will bend over and you can pull the coax through with it. You may have to put a hook on the end of a pole to reach the end of the fish tape and pull it toward yourself to attach the coax.

 

[RickC.]

Thanks Homer-- I was thinking about that earlier-- will probably have to push the fish tape through from the outside, tie a string onto it, pull it back outside, then tie it to the cables and pull them inside.

Heat and dust-- yay!

 

[HomerBB]

Thanks Homer-- I was thinking about that earlier-- will probably have to push the fish tape through from the outside, tie a string onto it, pull it back outside, then tie it to the cables and pull them inside.

Heat and dust-- yay!

Yep. That works. I've done that, too.
We used to cut the fish tape into section and put a loop on both ends so as to be able to pull cable from either end without having to reverse the fish tape back out with string on it. Sometimes getting a fish tape through some tight places was a one shot thing.

 

[RickC.]

OK, got it on the air just in time for FD to start. The bands aren't in great shape this afternoon, but we'll see if I can get an idea of how this thing works.


Rick

 

[RickC.]

I generally avoid contests for the same reason I avoid the mall on Christmas Eve, but FD at least confirmed the antenna works. I've not had a chance to wring it out on 20m in a sane environment yet but I have had gotten to test it on 10m some-- and these are just anectdotal observations made while operating-- I don't have a test range at my house!

The local 10m net doesn't meet until tomorrow night and I'll play with it more then, but I was able to have a few "pipeline" QSOs on 10. The longest one just a few minutes ago with a station in Virginia Beach.

Front lobe of the beam- he was 10/9.
Off the back- S6 to S7
90 degrees to the side- S2 to S3

Other tests have shown similar results. In other words, this antenna behaves just like a 3 element yagi, which it is.

I already know that the 20m f/b is not as good as this, which is to be expected. The band was so crowded and noisy during FD (at least during the first few hours) that it was hard to get a good read of what it could do, though I did have solid contest contacts with stations that were barely readable on the dipole. Many stations off the ends of the dipole were not audible at all but were sold copy on the yagi pointed at them, but this was to be expected also.

No surprises so far, and no TVI/RFI when running 500W (SB-200) except for my wife's PC speakers (which probably don't have jack for RF shielding) so I'll have to find some snap-on ferrite cores for that.

I'll comment further when I can do more with it on 20. The Es stuff on 10 is fun, but I'd like some 20 minute European ragchews to really see how this antenna does.

Rick

 

[RickC.]

OK- 20's not in the greatest shape, but that can make for a good antenna test. Again, these are just informal tests and I don't pretend they are the equivalent of precise measurements. But-- boom height is just over 1/2 wave on 20 meters, rig used: Icom 718 into my old Heath SB-200:

Barcelona- received 5 x 15/9 report
DX station was 10-15/9 on front of the beam
S8 off the back
S2-S3 off the sides
S7 on a dipole at 30'

Rio Negro, Colombia- another 5 x 15/9 report
DX station was 10/9 on front of the beam
S7 off the back
S4-S5 off the side
S7-8 on the same dipole

The dipole runs SW/NE, so the EA was off the ends and the HK was nearly broadside to it.

Just tuning around listening to stateside stations, depending on the distance/angle, receive signals range from being almost equal between the beam (front lobe) and the dipole to being very dramatic: S7-8 on the beam, then just disappearing when switching to the dipole. Anyone who has used a beam antenna and still had a vertical or dipole to switch to has seen the same thing.

So a couple of things I can draw from this, even this early on:

1. The f/b ratio on 20 meters is noticeably better than the VE7CA antenna. His spacing on 20 was dictated by the size of his car's trunk. Expanding that out to near 1/8 wave appears to have helped with that.

2. Even a 2 element yagi can make the difference in a solid contact and not even hearing a station (or being heard). A 2 element beam is a worthwhile project I think.

I'll put together a drawing with the dimensions when I have a chance-- the only thing is I don't know how long the driven elements are. I just tuned them until they were right and it was so hot on the roof that I didn't think to measure them and write it down!


Rick

 

[Hutch]

Thanks for the write-up, I must say it's very inspirational, makes me want to get out there and build one.

Great job, thanks

VE3HTU

 

[RickC.]

Many thanks Hutch-- and you should build you a beam! I don't know how the fiberglass would fare up in VE3 land with the ice, but it's handled 50 mph gusts here with no ill effects so far. The more I use this I really like it. I also thought I'd take a chance with a rebuilt Alliance U-100 rotor I had (from Norm's) since it's rated at 5.0 sq ft. So far so good, but MAN that rotor control makes a lot of racket!

I'll play with it some more over the holiday weekend and see if anything else interesting pops up with it, summarize the build with what I learned from it, and get a drawing up here.

Thanks!

Rick

 

[HomerBB]

Fine job on the beam(s), Rick. I've enjoyed the journey from start to finish.

 

[RickC.]

Thanks Homer-- it's put me behind on the little ground plane project, but I think I can get that done soon.

 

[RickC.]

It's amazing what even 1/4 inch of ice will do to the windloading of an antenna or tower.

Yep...

The mast buckled some time during the night last Tuesday, with all guys intact. This was a fun antenna while it lasted, unfortunately I didn't get to use it all that much. My work situation changed just a couple of weeks after I finished this antenna and I have spent a lot of time on the road.

From what I can see (and I don't remember hearing anything), it didn't come down hard but just slowly bent over. Unlike the gambling house, it didn't die with an awful sound... The roof isn't damaged, and the crappie poles are fine.

Not sure what's next, but I won't go this route again-- I was pushing the limits of what you can put on a push up mast anyway. It held up to some stiff winds just fine, but 1/2" of ice took her on down.

Next.


Rick

 

[HomerBB]

What a deal . . .
I've seen the same over this way. I am more concerned about ice than wind in most cases. When it thaws just get a stiffer mast and get back on the air.

What about the little ground plane project you were talking about?