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Base Signal Engineering DPX-2000A

Mar 22, 2018
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Hi all, first time posting here. I recently picked up a N.O.S. DPX-2000A base antenna and can't find any info on it. I do know that is vertically and horizontally polarized. Is anyone familiar with this antenna? Any info would be greatly appreciated. Thank You and 73's!
 

dave457

Sr. Member
Jan 3, 2009
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Looks like a 5/8 vertical ground plane antenna to me
 

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Marconi

Usually if I can hear em' I can talk to em'.
Oct 23, 2005
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The DB

Sr. Member
Aug 14, 2011
1,988
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Don't 5/8 wave antennas require a loading coil?
Loading coils are one way of matching said antenna, but not the only way. Any form of impedance matching that can convert the feed point impedance of said antenna to a 50 ohm resonant load will work to match said antenna. In the case of this antenna, a loading coil is just one way to accomplish this.

The Super Penetrator uses a hairpin type match. Several antenna designs use a tapped coil, which should not be mistaken as a loading coil as it functions very differently. Some antennas that use said methods, such as the Maco V5/8 and V5000 have a capacitor as well, in the case of the Maco antennas it is actually hidden in the design. Others use a design that doesn't require the capacitor.

The Imax 2000 actually uses a capacitor up on the antenna itself as a load, which allows them to use what is essentially a half wavelength matching transformer to match said antennas.

I've seen a guy use a gamma match to match a homemade 5/8 wavelength antenna before, as well as stub matching.

In short, there are any number of ways to match a 5/8 wavelength antenna that doesn't require a loading coil. However some people will mistake some of said components to be the same as a loading coil simply because somehow they look the same.


The DB
 
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Reactions: Ryan(169Nor.Cal.)
Mar 22, 2018
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Hey Ryan, why don't you give us some good close and mid-range pictures. I would like to see this antenna up nice and close so we can get some ideas on what is going on with this strange bird.
Here is a shot of the base. And yes there are two feed points. One for the vertical and one for the radials.
 

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BJ radionut

Supporting Member and 6m addict
May 9, 2008
4,123
4,655
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There was another vertical antenna that fed the radials for horizontal, I just can't remember who it was that built it.
We're is @bob85, bet he knows what it is.
1-bd0610.jpg

556df6e1b782f_360016b.jpg

EH0442.jpg
 

AudioShockwav

Extraterrestrial
Staff member
Apr 6, 2005
7,348
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Bob claimed to have the Saturn, and I think he also said he never built the kit. o_O

73
Jeff
 

Squints

Active Member
Jan 24, 2021
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I wanna build a coaxial matching transformer to match 75 ohm coax to a 50 ohm antenna on 11 meter band using rg-58u velocity 66.0 as the transformer between the antenna and the 75 ohm feedline.
I dont understand the formula so could somebody just calulate this for me real quik just need tonknow how long ahould my rg-58u transformer ahould be
 

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