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New Penetrator spt-500

turborich

Cheerleader
Mar 24, 2017
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Have a few questions about the new Penetrator spt-500. When I say new, I'm talking about the newest version with the new style of matching network. It's no longer the traditional wire with the two humps. It's now shorter and made of a flat piece of cut out aluminum.

Anyways, I've been using a Sirio Tornado 27 for years, SWR was excellent across all 40 channels. The wind finally snapped the plastic piece at the bottom so that was that. Just about everyone and their brother suggested getting the Penetrator Spt-500. However when it came it had the new style matching network. Anyways, put it up and adjust it the best I could with both my MJF-259b and my inline SWR meter. I prefer to adjust for the lowest on channel 20. So 20 is 1.1, however the SWR climbs up the closer you get to both channel 1 and 40 with the middle being the lowest.

My Sirio Tornado 27 was very broadbanded, however this spt-500 doesn't seem to be. With 2000 watts going out, I'm seeing 10 watts coming back on channel 20, however 30 watts coming back on both 1 and 40 due to the higher SWR. I don't want to hurt my amp while on channel 6 or 38.

Has anyone else had this issue? Any possible suggestions? Thank you.
 

a well designed and not run to the max amplifier has enough headroom to deal with the few watts returning from your antenna , 30 watts return from 2000 is actually nothing to worry about if you leave some headroom, i.e. not driving it to or over the limit of the amplifier.
My SB-1000 refurbished can do 1000 watts but i limit that to 800 watt output all the time, swr is the worst on 80 with SWR of 1:1.7 the amplifier does not even notice it well tuned. ( 3 - 500 ZG)

Since i don't know your amp or reserve it has it is for you tto decide what to do.
My Imax was chosen for broadband use on 10/12/15/18 for a reason,
Limit output to 1900 watts that will give the amp enough headroom, nobody will notice the 100 watt less, you need a 3 db gain to be barely noticed which is a doubling of the output power.
 
Turborich, according to my model of an older version of the SP500 is showing a <2.00:1 SWR bandwidth of 1.17 mhz...and that is pretty narrow, but I think most 5/8 wave GP tend to show a narrow bandwidth and for sure compared to a 1/4 or 1/2 wave.

I also have a model of the Tornado 27, but I had to guess at the coil dimensions. I missed a little with the resistance showing 62 OHMS. Even so, the reactance is very good and the match shows 1.245 at resonance. It also shows a narrow bandwidth for <2.00:1 SWR, with 1.20 SWR at 27.200 MHz and it shows SWR <1.50 across the 40 channels.

If the SP500 model is close to right, you'll notice the bandwidth curve is not nice and smooth like the Tornado 27, and maybe that has some effects you are experiencing with your amp. The SP 500 is noted to handle 1500 watts, so you may also be getting some arching at the top insulator.

The gain and angle for both models are very close to the same with the edge going to the Tornado 27. However with the little miss match in the 27 model at resonance the gain may be showing to be overstated a little. I will only know that if I can ever get some good dimensions for the Tornado 27 coil.

Turborick, since your Tornado 27 is broken maybe you can get me all the dimensions I need to improve my model?

Below are two overlays showing the antenna gain and angle patterns as compared. Also note the slight skewing in the SP 500 pattern, in red, that I think is due to the matching device. I will post the rest of the models later today and you will also be able to see the skewing in the BW curve as well.
 

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Here is an old report on the SP500 being tested. It confirms my models SWR bandwidth if nothing else. Try the PDF file feature to Zoom In...it might help you see better.
 

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Turborich, you don’t show your SWR figures in order to compare. Also, you don’t tell us what type of amplifier you have to tell you if it can withstand SWR of 2.0. Tube ones can hold ok, transistorized ones tend to protect themselves on those SWR’s.

Since this antenna is “ illegal” to be used in cb, HyGain don’t show you cb length , I think it is around 270” .

According with a friend gave me ( who had the old version ) I adjusted my antenna to 268” . That measurement gave me the lowest SWR on channel 40. I should lengthen it by 2 inches to have the lowest SWR on channel 20.

New HyGain SPT-500

Here are the numbers when I adjusted it for the first time:

Frequency ———- SWR

28.000 MHz. ———- 2.0
27.760 MHz. ———- 1.5
27.405 MHz. ——— 1.0
27.045 MHz. ———-1.5
26.780 MHz. ——— 2.0

Bandwidth = 1.220 MHz . This is pretty normal for this antenna.

Sirios have wider bandwidth, around 2.0 MHz. I’ve never had the Tornado 27. I can tell you the ones I have. For example,

Sirio Model ——— bandwidth

827 ———————-—-2.33Mhz
Gain Master ———- 6.25MHz ( Super widebanded)
Vector 4000 ——— 1.82MHz

The only drawback with the Gain Master is that it is rated at 400 continuous carrier. It will blow with 2,000 watts !

Non Sirio, the famous I-Max 2000 with a 3.2Mhz bandwidth.

Bandwidth is calculated from SWR of 2.0 up and 2.0 down

It’s been said that the narrower the bandwidth, the most efficient the antenna is on most of the cases.
 
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SPT-500
The height for a 23 channel radio is 22' 9 1/2"
The height for a 40 channel radio is 22' 6"
That's measuring from the bottom of the bottom insulator.

You're right r carl, but I'm not sure about the overall physical length of the radiator for this newest version of the SP 500 with the new beta match design...from the top of the mounting bracket up to the tip.

Maybe Turborich can get us some good details for the new dimensions, including the matcher wire lengths too...when he has some time.

I would like to model this new design and see if it made a performance difference too.

BTY brother TR, there is a thread on the SP500 with an idea that is supposed to help eliminate arcing at the top insulator under power and the problem with changing SWR when it rains.

New spt500 gamma
 
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SPT-500
The height for a 23 channel radio is 22' 9 1/2"
The height for a 40 channel radio is 22' 6"
That's measuring from the bottom of the bottom insulator.
I set mine at 22' 9" and had good swr on all 40 channels with the New STP 500 but thought I might have shortened it another 1/4" or more. The thing I don't like about the SPT 500 is the SWR goes hay wire in the rain but returns to normal after the rain stops. There is a fix for that on the internet somewhere and I'm looking to find it, if anybody knows please post it. Thanks
 
https://www.worldwidedx.com/threads/new-spt500-gamma.253565/


Eddie posted this right above your post

BTY brother TR, there is a thread on the SP500 with an idea that is supposed to help eliminate arcing at the top insulator under power and the problem with changing SWR when it rains.

New spt500 gamma


73
Jeff
Thanks man you are a Gem. I will check it out! I once had the SPT 500 and the M400 Star duster both set up at the same time for comparison purpose and found they both worked equally as well until it rained and then the M400 stayed rock solid. It's time to play again!
 
I just checked that thread and the flat strap matcher doesn't help with rain problem because mine had the flat strap. The search continues. I'm playing with the thought of a rubber boot, or the Maco V58
 
I guess I'm not understanding the long side up. I'll have re-look at my SPT 500 I figured it had to be shorting out in the rain. Thanks
 

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