In reply to G3CWI:
Richard,
How about a delta loop with its apex supported by a pole, e.g. 7m up. This should give a feed-point about 2.5m up.
I thought of building an antenna like this, but if it’s not worth the effort, I stay with my 2x7m dipole and a tuner.
73 Heinz
In reply to G3CWI:
Richard, in your modelling how does a dipole compare with a vertical with two or three elevated sloping ground plane elements, which is what I have built for the band so far. I thought that this probably has mechanical advantages over a dipole.
73
Brian G8ADD
In reply to OE5EEP:
Hi Heinz
That was one of the alternatives that I modelled. The dipole beats it by several dB at the sorts of radiation angles you need.
My dipole modelling was a halfwave dipole. 2 x 7m will cause lobe splitting which may not be helpful overall.
73 Richard G3CWI
In reply to G8ADD:
Not tried that yet at 12m. I will get back on that one. Elevated verticals actually don’t seem that good generally compared to a dipole at the same height.
The caveat here is that I model mostly over a flat earth - hence the need for some real tests on hilltops. Tom M1EYP and I plan to do this soon.
73 Richard G3CWI
In reply to G3CWI:
Richard,
A 2x7m dipole supported at 6m with 8m feed line is my universal antenna from 10 - 40m. The built-in tuner of the KX-3 can find a match within seconds on all bands.
I would have expected that a full wave delta loop would give a lower elevation angle than the dipole. On the other hand on summits you usually can profit from the sloping terrain around you. I guess no modelling software can accurratly cover these conditions.
Maybe you could comment on the ground conditions you are using in your simulations.
Do you know if the delta loop will eventually beat the dipole when it is raised further up? I do keep a 10m mast with a 2m extension as a spare…
73 Heinz
In reply to G3CWI:
The caveat here is that I model mostly over a flat earth - hence the
need for some real tests on hilltops. Tom M1EYP and I plan to do this
soon.
That should be good for a Radcom article!
73
Brian G8ADD
In reply to G8ADD:
That should be good for a Radcom article!
It should also be good for (several) lengthy sessions of data analysis in the pub.
In reply to G3CWI:
…and a long discussion on this reflector! I look forward to it!
73
Brian G8ADD
In reply to G8ADD:
Never mind the antenna, I can knock something up in no time.
I need to build a rig first.
Any suggestions for something simple - 1W to 2W CW?
Pete
In reply to G3CWI:
That was one of the alternatives that I modelled.
I’ve spent the last ten years modeling* as a career. I learned that the difference between theory and practice in practice is very much greater than the difference between theory and practice in theory! Or sometimes what actually happens is not at all what was expected and it’s time to revise the model!
I was planning on a trying a loop for this band along with some other antennas to see if they are an improvement on the 1/4wave GP or dipole. I find the suggestion the dipole is dBs better than a loop to be quite thought provoking. If that is the case why do people bother with other antennas? Possibly mechanical/environment reasons prevail. Or they’ve read stuff on the internet and so assume it must be true 
Anyway, as long as the propagation gods play along with us we should all have some real fun here trying different antennas in different situations to see what works well or not at all. It’s one of the reasons we have the rules for the 12m Challenge different from normal SOTA rules such that every 12m QSO will count even from repeated activations of the same summit. You can play with antennas and score. Then take the better designs up another summit and score QSO points and multipliers and have a good walk as well.
Andy
MM0FMF
In reply to G4ISJ:
Pete, I can recall designs for simple gear for 12m being published in RadCom, HRT etc. when these bands were announced (c. 1980). Of course that was 33years ago now. I’ve recently acquired all issues of 73 and Ham Radio on pdf (22GB) so I’ll have a look in there to see if there is anything. Technical Topics archives would be another good place to look.
Andy
MM0FMF
In reply to G3CWI:
This appears to back up your experience Richard.
http://www.w8ji.com/quad_cubical_quad.htm
73
Rick
Every time I look into the ‘best antenna for SOTA’ issue I always end up coming back to the half wave dipole.
The delta loop idea is interesting and I fancy giving it a try for 12m along with 20m also. I don’t think I’ve ever had a QSO on 12m so I’m keen to give this band a try during the summer.
Like Pete I’ve also been thinking about how to implement a couple of watts on 24MHz. Kits and designs seem in short supply for 12m
I have a bag of 9MHz crystals which I sorted in order of frequency; I have 3 or 4 very closely matched so I was thinking along the lines of making a superhet with a 9 MHz IF. My difficulty arises with creating the local oscillator frequency. I can lay my hands on some 8 MHz crystals but I doubt that I’d be able to pull the VXO low enough at double frequency.
A VFO at 15.9MHz is a scary thought so I guess I’m left with doubling a 7.95MHz VFO.
Maybe a cheap DDS could be used for the LO. I’m not worried about current consumption, I guess it’ll take a lot to get anywhere near the current consumption of an FT817.
Any ideas for a 24MHz QRP TRX gratefully received!
73, Colin, M0CGH
In reply to M0CGH:
5MHz VFO mixed with 20MHz TCXO + buffer and PA for Tx
On RX use the 5MHz VFO to mix 25MHz down for a 20MHz IF using 20MHz TCXO for BFO.
Maybe.
W7ZOI’s MicroMountaineer will work on 12m too. I have one of those about - somewhere…
http://w7zoi.net/mtnr4.pdf
Also see G3XBM’s Tenner:
http://homepage.ntlworld.com/lapthorn/tenner.htm
In reply to G3CWI:
Thanks Richard, some food for thought there. I still have my crystal testing jig so swapping to a 20Mhz IF wouldn’t pose too much of problem and crystals appear to be quite cheap.
I guess a K1SWL HiMite could be modified for 12m but power would be quite low. I never did get my 17m home brew HiMite working, I think I learned a lesson in proper RF shielding between stages there.
GQRP club has 12m crystals in stock but I haven’t seen any information stating whether they are fundamental or not. A RockMite could easily be modified for 12m but RX performance and TX power out are discouraging factors.
Colin
Edit -according to price list on GQRP site the 24.906 are 3rd overtone crystals.
In reply to M0CGH:
The GQRP 12m crystals are 3rd OT.
In reply to G3CWI:
In reply to M0CGH:
The GQRP 12m crystals are 3rd OT.
Replied at the same time!
In reply to M0CGH:
Would taking a 10m design down to 12m be worth considering?
Andy
MM0FMF
In reply to M0CGH:
I’ve started thinking about a rig for 12m too Colin.
Thinking about a DC VXO with a class E pinched from KD1JV’s design or a more advanced superhet using some kind of crystal mixer with a vfo suitably low to be stable-ish.
Or, I have a couple of ebay dds modules and an arduino board from a previous fad/experiment that would maybe work. Although a bit current greedy.
As for antenna, I’m with the dipole.
73,
Ian.
In reply to MM0FMF:
Would taking a 10m design down to 12m be worth considering?
Yes, that’s a possibility I guess.
Or maybe we could do a 3.5Mhz challenge instead
Colin