A while back, I made a monopod to use with my camera. Handy thing to use when I don’t feel like lugging around a tripod. Also serves as a nice walking stick.
On one of my last visits to Radio Shack, I picked up two telescoping antennas thinking that I could use them as dipole elements.
Add one section of aluminum angle stock, a bulkhead BNC jack, a couple 1/2″ 4-40 screws and nuts and now I’ve got a telescoping 2m dipole antenna attachment for the monopod.
It took me a while to figure out how I was going to insulate one of the telescoping elements from the angle stock. While I was studying the problem, a solution struck me: plastic wall anchor. Worked perfectly.
Tuning the antenna was a simple matter of adjusting the length of each telescoping antenna to get close to 1:1 across the 2m band.
Looks pretty good. I’ll check it again outside over the weekend and try it out with the HT.
If I hold it up in the air by the base of the pole, I can get the antenna about 2.5 m up in the air. I’m hoping I’ll be able to reach the two repeaters that are about 8 miles away a little better than I can with the HT antennas I already have.
Extending the mast all the way gave me enough height to swing one wire of the dipole over the roof.
The more open arrangement along with both wires of the dipole being more exposed seemed to make the antenna work better. The radio’s internal tuner will match on 40 m now (below that is still a no go), so it’s nice to be able to get that band back.
Noise floor on 40 m is still pretty high (around S7) so I probably won’t be able to hear much except for stronger signals.
First contact with the antenna and new mast was with W9ISF, Indiana State Fair special event station, on 20 m. Got a nice 57 signal report from him and he got a 55 from me.
Raising and lowering the mast isn’t too difficult, and hooking the antenna to the top of the mast makes it easy to attach and remove. Gravity helps with lowering the mast, and I think most of the work will be spent coiling the antenna back up for storage.
Now to acquire another 20 or 25 m of coax that I can use as additional feed line for experimenting with other antennas.
The antenna works. There wasn’t a whole lot to hear on the bands, so I’m not sure if the antenna’s performance is crap in its current configuration, or if it’s just the bands are crap today. I’ll spend some more time on the antenna and playing on the radio tomorrow.
The radio’s internal tuner will match the antenna from 20 m up to 6 m, but not on any of the bands below that. Better than I expected, although not having 40 m is a bit of a downer. The noise level on all the bands below 20 m was pretty high too (S7-9).
Now the dilemma is what to do with the antenna when the radio isn’t being used. The antenna and mast are pretty conspicuous when deployed, and we would no doubt get some naughtygrams from the HOA police.
With the mast down, there’s not much to see from the road or even the side of the house.
The antenna becomes pretty messy though and obviously makes mowing more difficult if I just leave it lying on the ground. The antenna would also exposed to full sun, which would probably shorten its life.
I think what will most likely end up happening is that the antenna will come off the mast and get coiled back up when it’s not being used. I can use an S hook to attach the antenna center to the top of the mast which will make for one less rope to deal with.
That means playing radio will end up being a little bit more work and a more planned activity. Won’t have to worry about the inevitability of the antenna or coax getting chewed up by the lawn mower though.
The fiberglass mast is attached to the fence, and the antenna is finally up in the air!
After pondering a few options for the mast, I decided to prop it up against one of the 4×4 fence posts and secure it in place using some hanger strap material.
By standing on a ladder so that I can reach the clamps, raising each of the mast sections is fairly easy. The hard part is not getting tangled up in the antenna wires and feed line while raising each section.
The antenna is a little more conspicuous than it was at the old house. With all but one of the mast sections extended, the center of the antenna is somewhere between 25-30 feet up in the air I think.
Lowering the antenna can be done by either lowering it from the rope (like a flag) or lowering the mast sections. With the mast sections all the way down, only a couple of feet or so of mast are left sticking up above the fence.
A quick look at SWR with my antenna analyzer suggests the arrangement isn’t optimal. The proximity of things like the house, fence and mast might be interfering with the window line segment of the antenna. Getting high SWR readings on 40 m, and 20 m looks marginal. 6 m and 10 m look ok, and parts of 80 m and 160 m might be doable (although the low-ish SWRs there might just be because of coax loss).
I haven’t connected the radio yet, so I don’t know how much noise there is yet. One of the antenna legs comes pretty close to the AC condenser outside, so there could be a fair bit of noise when the AC kicks in. With one quarter of the antenna more or less sandwiched between two houses, there’s no telling what the radiation pattern will look like.
Ordered an MFJ-1906 fiberglass mast from DX Engineering over the weekend and it arrived at the house yesterday.
I ordered the 33′ hose clamp version of the mast, but what ended up at the house was the 38′ quick clamp version (MFJ-1906HD). Even the label on box said it was the hose clamp version. Factory labeling error I guess. Can’t really fault DX Engineering for sending the wrong item.
Instead of the expected six 6′ sections of fiberglass tubing inside the box, there were seven 6′ fiberglass tubes along with 6 quick clamps. It’s a pretty compact package. One 6′ x 2.5″ OD tube with all the others nested inside.
The quick clamps need to be glued to each mast segment so that they don’t come off while you’re extending each segment. The only suitable glue I had was epoxy, so I just used that.
Final assembly is just a matter of adjusting the quick clamps so that the tubes slide into each other and holds securely when the clamp lever is in the down position. I marked the bottom end of each tube at 12 cm (the instructions suggest marking them at 1 ft (~30 cm) as an indicator to stop pulling each tube out.
Final length is just over 2.1 m (7′) and fully extended (leaving about 12 cm nested inside the previous segment) the mast is about 12.2 m (40′) long. Leaving about 30 cm nested in each segment would bring the total length down to just over 11 m (37′), which is still plenty long enough for my purposes. Probably a good idea to leave the thinnest tube nested a little further inside for extra strength, especially on a breezy day.
The mast seems pretty sturdy, although I can tell that getting it up is going to be at least a two person job. At somewhere around 10 kg (~20ish lbs), the mast doesn’t weight a whole lot, but the length can make it bulky and unwieldy. The quick clamps should easily hold each segment well enough for the mast to support a wire or other light weight antenna.
The quick clamps seem like they’ll need readjusting, especially if they’re being locked/unlocked frequently. Don’t drag it on the ground while you’re carrying it around, especially on hard surfaces or you’ll end up grinding away the mast.
Now to figure out how to secure the dipole to the top of the mast.