The inside diameter of the 10m pole is just over 44mm which means you can internally sleeve a 44mm tube inside the pole to give you lots of options for mounting.
The last section is a solid section (not hollow) which is nearly impossible to break.
They extend to 9.7m in length, which is exactly the amount you need to build a 40m ground vertical too. I added a coil once and made an 80m version too.
Customers have made 2-element yagis (see pic), dipoles and G5RV supports. Antenna supports are easy to build by removing the last three (3) sections and achieving a very good vertical non-metallic support at about 7m height.
Verticals resonate on the third harmonic too, so a vertical resonant on 7Mhz theoretically will resonate at 21Mhz. In my practical experience, you’ll find the third harmonic will be a little higher, probably 21.3Mhz.
You can add a second element too, as you would a fan-dipole and have another element for say 30m (about 7.5m long) and you’ll also get the 10m band for free. I added three elements once and added a 5m element too and achieved reasonable SWR across all bands including 40m, 30m, 20m, 15m and 10m. Some experimentation will be required by trimming the elements just right – and keeping each element away from each other.
I have built these both free-standing by using an internal sleeved tube concreted to the ground as well as guying them at the first section.
I have found that it is not necessary to tape each joint to stop it telescoping down on itself but for the sake of water ingress and long-term stability, I recommend you wrap a couple of turns of self-amalgamating tape around each joint to keep the inside fairly dry and ensure that the friction fit stays true. This will also stop ice forming.
I can supply other lengths to order but in my experience, amateur radio experimenters should purchase the longer length and if a shorter pole is required, remove the last sections which will have the effect of increasing the strength of the assembly.
Mounting ideas for doublets / G5RVs
Cable-tie your wire antenna to the very end of the last section, the one with the small ring at the end. Remove the three top sections and drop your feedpoint inside say the 7th section of the telescopic mast, leaving aside the remainder. Now you will have an antenna approximately 7m in height on a strong mast that won’t waggle about too much.
Mounting options for the mast:
- It so happens that a 44mm (1 3/4 inch I think) pole will slip up the inside of these poles so you could dig a 44mm steel or ali tube in the ground and leave it self supporting
- You can do the same as above but guy it too
- You can guy it directly onto the ground without supporting tube but maybe sit it on a piece of wood with a large bolt coming up inside so the pole doesn’t slip off
- You can tie it to a fence post etc.
There has been much research done on radials however if you want a 50 ohm match and good efficiency, use between 8 and 16 radials of not more than 7.5m in length (for 40m). I have run pile-ups to the USA on 40m with this arrangement. I have doubled the radials to 16 with no effect. Perhaps going up to 50 or 60 might have given me half an S point but seriously, you are into diminishing returns. I lay my radials on the ground and at home, the grass has gradually grown over them. Use any copper wire you can find. No need to spend lots of money.