1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice
Dismiss Notice
This forum does not allow a single user to have more than one username. If anyone wants to change their username contact an admin and it will be done. Multiple accounts belonging to the same member will be deleted without warning.

New Penetrator spt-500

Discussion in 'CB Antennas' started by turborich, Jul 31, 2020 at 7:01 AM.

  1. turborich

    turborich Member

    Joined:
    Mar 24, 2017
    Messages:
    14
    Likes Received:
    8
    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.
     

  2. Justme

    Justme Well-Known Member

    Joined:
    Jan 28, 2008
    Messages:
    337
    Likes Received:
    192
    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.
     
  3. BJ radionut

    BJ radionut Supporting Member and 6m addict

    Joined:
    May 9, 2008
    Messages:
    2,922
    Likes Received:
    2,716
    Slowmover likes this.
  4. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

    Joined:
    Oct 23, 2005
    Messages:
    6,456
    Likes Received:
    1,502
    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.
     

    Attached Files:

    #4 Marconi, Jul 31, 2020 at 10:54 AM
    Last edited: Aug 1, 2020 at 1:25 AM
    Shadetree Mechanic likes this.
  5. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

    Joined:
    Oct 23, 2005
    Messages:
    6,456
    Likes Received:
    1,502
    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.
     

    Attached Files:

    Shadetree Mechanic likes this.
  6. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

    Joined:
    Oct 23, 2005
    Messages:
    6,456
    Likes Received:
    1,502
    Here are the modeling details for the Tornado 27 vs. the SP500.
     

    Attached Files:

  7. Alexis Mercado

    Alexis Mercado Active Member

    Joined:
    May 17, 2016
    Messages:
    92
    Likes Received:
    45
    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.
     
    #7 Alexis Mercado, Aug 2, 2020 at 5:24 AM
    Last edited: Aug 2, 2020 at 5:51 AM
  8. r carl

    r carl Active Member

    Joined:
    Jan 26, 2020
    Messages:
    87
    Likes Received:
    127
    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.
     
    Slowmover and Alexis Mercado like this.
  9. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

    Joined:
    Oct 23, 2005
    Messages:
    6,456
    Likes Received:
    1,502
    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
     
    #9 Marconi, Aug 3, 2020 at 3:49 AM
    Last edited: Aug 3, 2020 at 3:55 AM
    r carl likes this.

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!