Bumping this because I used that pack in anger yesterday to activate w4v/sh-030 (Blue Mtn). Due to time constraints, I did it as a drive up and parked at a trailhead about a quarter mile from the summit (normal entry point for me is one that is about a 2 mile hike). I was able to get the Arrow antenna, a thin pad to sit on, 1 of my two radios, a bottle of water, my 6m EFHW, a 2m j-pole, 15’ RG174 coax, 25’ RG174 coax, and my throw line in it.
It was comfortable to wear, but moved around a little bit. I wouldn’t recommend it for long hikes, but I’d consider it tolerable for 2 miles or less. I think it’ll be my dedicated VHF activation pack.
As for the activation, it was a bust. The summit is studded with multiple radio towers and is an RF QRM nightmare on VHF (especially 2m). It’s doable with a single band radio like an Icom IC-V8, but virtually impossible with anything touting “wideband receive”. I was testing my new TH-D74 (which has “wideband receive”) and brought my VX-7 along (hence the 6m EFHW). Needless to say, both were swamped by the QRM. I did hear a guy on 220mhz call to me, but I was using the D74’s rubber duck antenna for that and he couldn’t hear me well enough. I may have to build a j-pole for that band as it seemed to work better on the summit than 2m.
I cannot emphasize how highly I recommend doing this! With a drill press (ideally) and some time, you can lighten the boom by 40%. Here is Mike W8LID’s article on doing this: Dropbox - LidStick.pdf - Simplify your life
My only recommended adjustment to these instructions was an idea by RJ WY7AA to use a 1/2" bit, which increases the amount of material removed but requires more precise drilling.
Chris here is my SOTA/work BP I have the collapsible-boom Arrow in Purple bag shoved in side of largest compartment. I use a short piece of line to tie zippers together.
I am looking to make my own arrow antenna for 70cm and 2m.
I have sourced some inexpensive arrow shafts (less than £2 each) and am trying to decide on a couple of other design choices that I was hoping for advice.
Will be using a 3/4 inch square cross section boom…but not sure what wall thickness. Is 1.25mm too thin…the pictures linked to above suggest a thicker wall. Could you confirm what wall thickness the arrow antenna uses please?
For the gamma match, i would like to use the same style as the arrow antenna…but i cant quite work out the design of the bnc connector block: Is the block machined and tapped to take a chassis mount bnc…I can’t see how the rear nut can be attatched to the bnc so assume it is screwed into a tapped hole, but equally i have never seen bnc connectors screwed into a tapped hole previously (as it would surely loosen with use).
Thanks for any help.
(Apologies for the thread hijack/resurrection …will post any progress updates seperately when i get properly started)
My Arrow yagi shaft measures out to 1.55mm wall thickness. I think 1.25mm would be fine as the Arrow shaft is frequently deemed too heavy for backpacking use.
I agree with your assessment that the BNC is screwed into a tapped hole. I can’t see any other way they would have assembled it. With sufficient torque and thread locker, it would be secure.
Most of the ones i can find on the web use a piece of angle aluminium for the bnc. This is less functional for a portable antenna as the bnc is attached to the boom.
In the arrow antenna design the use of a machined block allows the gamma match to be held by the driven element, such that the gamma match, driven element and bnc are a single unit that removes from the boom in one piece, without any screws other than the threaded stud in the driven element.
Thanks for the link, I’ve not seen that site before.
The part I can’t quite work out is shown in the image below (adapted from a worldwidedx review). The conductor (red line - my addition to the image) must be soldered to the BNC, and presumably passes through some insulation (grey lines - also my addition) within the connector block. I can solder the conductor to the BNC after first passing it through the connector block…but when I then come to screw the BNC into the connector block, the 90-degree bend in the conductor will prevent the BNC screwing into the block.
Perhaps I would need to have a second solder joint at the 90-degree bend - rather like right-angled connectors. But somehow that doesn’t seem like the right way to do it.
A BNC that push-sits into the connector block, with some way to ensure good electrical contact would be easier but no such thing seems to exist.
BNC is 3/8 UNC thread IIRC. You’ll need to have the block tapped and drilled. You’ll really need another antenna to measure as you need to get the correct thickness of wire and the hole diameters right as it forms the capacitor in the match. Of course you can try to copy it but without a genuine item to copy it all becomes a lot harder in getting the dimensions right and then you’ll have fun and games seeing if you can get an acceptable match.
That’s why I suggested copying an example with dimensions etc. as they are likely to be the easiest route to success. Of course, a wise man puts the given dimensions into the formula to ensure what is on the web is accurate as many who made ribbon J-pole antennas will attest. Or make DK7ZB feeds which just work.
I was hoping i could reverse engineer the arrow antennas gamma match close enough that there would be sufficient adjustment of the tap along the driven element to achieve a match.
I can always try other methods later if i fail.
Of course, the main reason for doing it is that I saw the price of the arrow antenna (£150) and thought i could make a clone much cheaper.
Of course, i will end up spending £300 on parts, several weeks of time and end up with something that doesn’t work. But should learn a few things.
[quote=“M0MZB, post:44, topic:25767, full:true”]
Of course, the main reason for doing it is that I saw the price of the arrow antenna (£150) and thought i could make a clone much cheaper.[/quote]
Which model are you looking at that is GBP150? My 2m 3-element model was about $80, which is closer to GBP60 (too lazy to do the currency conversion). Of course shipping is a factory, but I can’t see shipping being GBP90.
This! I work at the sharp end of custom silicon designs for leading companies. There are so many things that all of you own that will include some of our silicon designs but NDA’s mean I can’t say. We’re helping our customers get their multi-billion transistor designs working. It’s cool seeing a new model of car come on sale knowing you helped in getting the customer’s software to work.
But that is nothing to the pleasure I get from making antennas from a few bits of wire cut and arranged just right and being able to have QSOs with them. So do persevere with this Matthew, even if it seems to take forever and you seem to never make any real progress. When you actually succeed you wont be able to fit the grin on your face.
