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New Sirio Tornado 27
- Thread starter Galaxy 959
- Start date
222 or anybody else, if you can help me further with the dimensions that would be great.
I'm getting a good match right now, but I had to adjust the overall length shorter that the 7230 mm specs overall length calls for. I think maybe this is why I see the bandwidth being a little more narrow than I would expect.
I'm expecting a BW = <>2 mhz at <2.00:1 SWR, instead of 1 mhz. With this out of whack a bit...I figure something is wrong in the dimensions for my model.
Just to be sure I need confirmation in inches for:
Average space between coils, center to center.
Coil width diameter, outside to outside.
Coil height, just close to the tallest points will do.
Coil wire diameter.
Coil number of turns, The spec sheet shows 5 turns and that is what I used.
Length of the aluminum mounting tube and diameter at the base of the antenna.
Overall length from the top of a radial to the top of the coil, just to be sure.
Thanks if you can help.
I got about 1" between coils center to center, my measurements could be off as the bottom section has been thrown around some. As far as coil length I found it to be approx. 68" which I posted back a few posts ago. Also it's 1/4" solid aluminum for the coil or what appears to be #2awg solid aluminum. It's 6.5 turns as already stated. Length from top to bottom of coil is approx 6". SO239 stub length is 3". This is the stub that connects the coil to the center pin of the SO239. From center of hub to top of coil is 8.75" approx.
Hope some of these measurements help. I am not entirely sure they are 100% accurate, but they should be close enough. Again, hope this helps.
Hope some of these measurements help. I am not entirely sure they are 100% accurate, but they should be close enough. Again, hope this helps.
Thanks for you guys working with me on this model. I've tried all the iterations for the dimensions, but nothing makes the bandwidth better than about .80 - 1.20 mhz, and I suspect it should be broader.
I at least know the model works to produce a good match for a 5/8 wave antenna that has 200-300 ohms of reactance without a matching device.
I at least know the model works to produce a good match for a 5/8 wave antenna that has 200-300 ohms of reactance without a matching device.
try that skip whip in the plans i provided if you get bored..curious about it as the software i use does not do verts (i only build beams) and i dont think anyone has done it in modelling
Don't forget to remove the mounting tube & hub length from the overall electrical length.
I'm not sure what length that is, that's why I asked several posts back for that dimension.
A true 5/8 (.625) for 27.2 is dead on 22' 7.2"
- minus the velocity factor of aluminum in air (.9979),
- minus the average circumference x .707,
or somewhere close to 22' 5".
Depending on the matching network this will vary +/- a few inches.
Case in point:
Old school Penetrator, 1st generation for 27.11mhz (center of 23 channel band)
11803 (speed of light in MHz-inches) x .625 ÷ 27.11Mhz = 272.1" = 22' 8.1"
272.1 x .9979 (VF) = 271.5"
271.5" - 9.5" (top hat radial length) = 262"
262" - 1.75" (.707 average circumference) = 260.25"
260.25" + .5" (ground radial bracket plates) = 260.75"
260.75" + .75" (coax connector) = 261.5"
261.5" + 12" (Base Bracket) = 273.5"
According to HyGain overall length = 22' 9.5" = 273.5"
Old school Penetrator, 1st generation for 27.11mhz (center of 23 channel band)
11803 (speed of light in MHz-inches) x .625 ÷ 27.11Mhz = 272.1" = 22' 8.1"
272.1 x .9979 (VF) = 271.5"
271.5" - 9.5" (top hat radial length) = 262"
262" - 1.75" (.707 average circumference) = 260.25"
260.25" + .5" (ground radial bracket plates) = 260.75"
260.75" + .75" (coax connector) = 261.5"
261.5" + 12" (Base Bracket) = 273.5"
According to HyGain overall length = 22' 9.5" = 273.5"
NB, I took 14" inches off for the mounting tube to get my working overall length, but that 14" inches was just a guess. After a model is completed, I just use the overall to try and confirm the model is close. Even so, the model could still have errors elsewhere.
I think I'm working with about the same dimension you noted for overall for a 5/8 wave, but these little differences, even if adjusted, would not fix this model regarding the bandwidth. Any way I go from here, longer or shorter, the models match will suffer, so there may be a combination of several errors in the mix of 38 wires used in this model.
Even a model as simple as the T27 there are many dimensions that come into play. The specs for this antenna show a <2.00:1 bandwidth on 1.3 mhz, which is pretty narrow...so maybe the model at 0.8 mhz is close enough and the other performance details look pretty good to me.
Try adding full 1/4 wave radials to see if the bandwidth is improved..?
The P500 is about 2.0MHz @ 2:1 swr.
You did good 222. I'm just old and modeling has me detail crazy.
The BW goes from 0.80 to 1.00 by making the radials 108" inches, but the gain drops a little bit.
Here is the model with the matching information. I adjusted this model to resonance at 27.205 mhz, so the guesstimate length of 270.6" was changed to 271.3" inches at resonance for the overall radiator length.
I just tried making it 277.7" long and the gain dropped to 3.87dbi gain at 172* degrees from 4.14dbi at 172* degrees for the .625 mhz resonant model. Re-tuning the reactance out might make up some difference however, but I'm not sure. I would have to reconfigure the coil design and then I would just be guessing again.
I just don't think a .64 wave shows any advantage at 11 meters...maybe a ground mounted low frequency .64 antenna would show some difference.
Maybe tomorrow I will scale my model and check this out. I need to check if the scale feature works on a model with a coil that has a known good match anyway.