loopantennas@groups.io | RF Systems DX-One Pro MkII

Fraser

Hi All,

A new question to ponder for the Group.

I own an RF Systems DX-ONE Pro MKII and have tried to establish
exactly what it is from the manufacturer.... they are staying
silent :-(

For those not familiar with the DX-One, it looks like a giant egg
beater and if you believe the sales blurb it uses a high performance,
very low noise overload resistant amplifier designed for the Dutch
Military. Yet another mystery amplifier design !!!!

I can vouch for the low noise element of the claim and it does
perform very well at my rural UK location with good rejection of the
house noise field.

What still mystifies me is exactly what it is in terms of antenna
type.

It looks like the Bellini Tosi crossed loop DF antennas that I used
to use on ships so I wondered if it is a crossed Bi-Loop to give
omnidirectional covereage ? I suggested this to the manufacturer and
received no response. It could be a compound monopole (folded up into
the diamond shape) but the antenna is ground independant and requires
only a safety ground for it's inbuilt ESD protection.

I have gone as far as X-Raying the antenna "guts" but that did not
reveal it's secret. there is a complex amplifier and several
torroids. One appears to connect to the "loop arms" and another is at
the output connector end of the amp.

I should be grateful for any comment that this groups members may
have on this antenna and it's design principle. Loop or Not Loop
antenna, that is the question :-)

I will post a picture of the DX-One in the photos area of this group
for those who do not know of it.

Fraser

Fraser

#3431

Ref the DX-One and "what is it"

I see that Universal sell it so there web site gives a good view of it.

I will upload the PDF instructions and specs to the files area for
Group comment.

Cheers

Fraser

Fraser

#3433

CORRECTION.....

--- In loopantennas@..., "Fraser" <fraser.castle@...> wrote:

Ref the DX-One and "what is it"

I see that Universal sell it so there web site gives a good view ofit.

I will upload the PDF instructions and specs to the files area for
Group comment.

Cheers

Fraser
OOOOPs, I forgot the url for Universal !

Here are some urls related to the DX-1 and a review :-)

and a review here....

fraser

#3434

Dear Fraser

had a look and look at the specs

I think there is a big clue in the gain as it is only 10 dB

to me that indicates a David Norton Noiseless Amplifier and likely very close to what
Dallas Lankford laid down in early 1990s

the transformers here should be three

[1] a centre-tapped input 
[2] the norton transformer 
[3] the output transformer

one of these transformers is a toroid for sure ie the norton although this could be made as a binocular

however either of [1] or [3] could be a mini-circuits plastic block 

just my take

Paul V Birke PEng
Guelph ON Canada

Show quoted text

----- Original Message ----
From: Fraser <fraser.castle@...>
To: loopantennas@...
Sent: Sunday, May 13, 2007 7:56:16 AM
Subject: [loopantennas] Re: RF Systems DX-One Pro MkII - Bi-Loop or not ?









  


    
            CORRECTION.. ...



--- In loopantennas@ yahoogroups. com, "Fraser" <fraser.castle@ ...> wrote:

Ref the DX-One and "what is it"I see that Universal sell it so there web site gives a good view of it.

I will upload the PDF instructions and specs to the files area for Group comment.CheersFraser

OOOOPs, I forgot the url for Universal !



Here are some urls related to the DX-1 and a review :-)



 l-radio.com/ catalog/sw_ ant/1246. html



 systems.nl/ DX-one.html



. at/DX_One. php



and a review here....



. info/equipment/ dx1pro.dx



fraser





    
  

    
    




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n2chi

#3436

Hi Fraser,
I hadn't thought "polarization fading" to be a big problem, although a
real phenomenom, else every antenna since Marconi would have been egg-
shaped I'm thinking.  I'm no expert, however.   I'd guess the low noise
comes from the quiet electronics and/or the loop aspect of the antenna, 
if it is a loop.
Universal's write-up calls the antenna omnidirectional without regard to
frequency, so that doesn't sound like a loop.  The manufacturer's write
up says their antenna is a "....combination of 2 loops, radials and a
vertical receiving element."   If the antenna is simply a vertical, I
could imagine the loops performing a Yagi-like reflector function.  But I
don't think they would affect the polarization or phase.  I guess that
like most antennas, one has to A/B it with another to compare.  Bring it
over to my deck and we'll try it against my Wellbrook.
Dave

Show quoted text

--- In loopantennas@..., "Fraser" <fraser.castle@...> wrote:

Hi All,

A new question to ponder for the Group.

I own an RF Systems DX-ONE Pro MKII and have tried to establish
exactly what it is from the manufacturer.... they are staying
silent :-(

For those not familiar with the DX-One, it looks like a giant egg
beater and if you believe the sales blurb it uses a high performance,
very low noise overload resistant amplifier designed for the Dutch
Military. Yet another mystery amplifier design !!!!

I can vouch for the low noise element of the claim and it does
perform very well at my rural UK location with good rejection of the
house noise field.

What still mystifies me is exactly what it is in terms of antenna
type.

It looks like the Bellini Tosi crossed loop DF antennas that I used
to use on ships so I wondered if it is a crossed Bi-Loop to give
omnidirectional covereage ? I suggested this to the manufacturer and
received no response. It could be a compound monopole (folded up into
the diamond shape) but the antenna is ground independant and requires
only a safety ground for it's inbuilt ESD protection.

I have gone as far as X-Raying the antenna "guts" but that did not
reveal it's secret. there is a complex amplifier and several
torroids. One appears to connect to the "loop arms" and another is at
the output connector end of the amp.

I should be grateful for any comment that this groups members may
have on this antenna and it's design principle. Loop or Not Loop
antenna, that is the question :-)

I will post a picture of the DX-One in the photos area of this group
for those who do not know of it.

Fraser

n2chi

#3435

Hi Fraser,
I hadn't thought "polarization fading" to be a big problem, although a
real phenomenom, else every antenna since Marconi would have been egg-
shaped I'm thinking.  I'm no expert, however.   I'd guess the low noise
comes from the quiet electronics and/or the loop aspect of the antenna, 
if it is a loop.
Universal's write-up calls the antenna omnidirectional without regard to
frequency, so that doesn't sound like a loop.  The manufacturer's write
up says their antenna is a "....combination of 2 loops, radials and a
vertical receiving element."   If the antenna is simply a vertical, I
could imagine the loops performing a Yagi-like reflector function.  But I
don't think they would affect the polarization or phase.  I guess that
like most antennas, one has to A/B it with another to compare.  Bring it
over to my deck and we'll try it against my Wellbrook.
Dave

Show quoted text

--- In loopantennas@..., "Fraser" <fraser.castle@...> wrote:

Hi All,

A new question to ponder for the Group.

I own an RF Systems DX-ONE Pro MKII and have tried to establish
exactly what it is from the manufacturer.... they are staying
silent :-(

For those not familiar with the DX-One, it looks like a giant egg
beater and if you believe the sales blurb it uses a high performance,
very low noise overload resistant amplifier designed for the Dutch
Military. Yet another mystery amplifier design !!!!

I can vouch for the low noise element of the claim and it does
perform very well at my rural UK location with good rejection of the
house noise field.

What still mystifies me is exactly what it is in terms of antenna
type.

It looks like the Bellini Tosi crossed loop DF antennas that I used
to use on ships so I wondered if it is a crossed Bi-Loop to give
omnidirectional covereage ? I suggested this to the manufacturer and
received no response. It could be a compound monopole (folded up into
the diamond shape) but the antenna is ground independant and requires
only a safety ground for it's inbuilt ESD protection.

I have gone as far as X-Raying the antenna "guts" but that did not
reveal it's secret. there is a complex amplifier and several
torroids. One appears to connect to the "loop arms" and another is at
the output connector end of the amp.

I should be grateful for any comment that this groups members may
have on this antenna and it's design principle. Loop or Not Loop
antenna, that is the question :-)

I will post a picture of the DX-One in the photos area of this group
for those who do not know of it.

Fraser

#3437

Hi Fraser and All

sorry scratch all that I just transmitted

the 10 dB is the antenna alone  LOL

oh well

Paul

Show quoted text

----- Original Message ----
From: Paul Birke <nonlinear@...>
To: loopantennas@...
Sent: Sunday, May 13, 2007 12:00:04 PM
Subject: Re: [loopantennas] Re: RF Systems DX-One Pro MkII - Bi-Loop or not ?

            Dear Fraser

had a look and look at the specs

I think there is a big clue in the gain as it is only 10 dB

to me that indicates a David Norton Noiseless Amplifier and likely very close to what

Dallas Lankford laid down in early 1990s

the transformers here should be three

[1] a centre-tapped input 

[2] the norton transformer 

[3] the output transformer

one of these transformers is a toroid for sure ie the norton although this could be made as a binocular

however either of [1] or [3] could be a mini-circuits plastic block 

just my take

Paul V Birke PEng

Guelph ON Canada

----- Original Message ----

From: Fraser <fraser.castle@ virgin.net>

To: loopantennas@ yahoogroups. com

Sent: Sunday, May 13, 2007 7:56:16 AM

Subject: [loopantennas] Re: RF Systems DX-One Pro MkII - Bi-Loop or not ?

CORRECTION.. ...

--- In loopantennas@ yahoogroups. com, "Fraser" <fraser.castle@ ...> wrote:

Ref the DX-One and "what is it"

I see that Universal sell it so there web site gives a good view of 

it.

I will upload the PDF instructions and specs to the files area for 

Group comment.

Cheers

Fraser

OOOOPs, I forgot the url for Universal !

Here are some urls related to the DX-1 and a review :-)

 l-radio.com/ catalog/sw_ ant/1246. html

 systems.nl/ DX-one.html

. at/DX_One. php

and a review here....

. info/equipment/ dx1pro.dx

fraser

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Fraser

#3438

--- In loopantennas@..., Paul Birke <nonlinear@...> wrote:

Hi Fraser and All

sorry scratch all that I just transmitted

the 10 dB is the antenna alone  LOL

oh well

Paul

Hi Paul,

Thanks for the input.

The DX-One base unit has unusual calibrations on the attenuator.
Instead of just showing the inserted attenuation it shows the system
gain.

The +10dB position is a straight through connection and is described
as +10dB because the antenna head is stated as having a gain of 10
dB. The 0dB position on the base unit is actually an insertion of
10dB attenuation. Theoreticaly in this position the input to the
receiver splitter is the same as the signal strength at the antenna
elements without any gain. This does not take account of feeder
losses though.

The base unit is a work of art. It's a very solid affair and contains
a low noise 28 Volt d.c regulated power supply, a calibrated stepped
attenuator, A MW filter and a high quality splitter. I bought a
couple of extra base units from Lowe(UK) last year for ?20 each. They
are easy to convert to 12V output and work very well with any phantom
powered active antennas.

I will have to look out the X-Rays that I took of the Head unit
electronics as they may be of interest.

I note that the review that I refered to states that the DX-One
requires an excellent ground plane. I have the DX-One MKII and the
only groundplane requirement detailed in the instructions is for
static discharge purposes. The same is not true of my RFS DX-500
which requires an excellent groundplane to perform well.

Fraser

#3439

Dear Fraser

In this case for direct feedthru I guess I un-tract my retraction (LOL again)

smells like a Norton amp with this gain range  ie 8 to 12 although with higher turns can get to near 20  however 10 is a clue to the noiseless Norton amp in my opinion

(not to say other configurations will not end up something like this, such as a grounded base bipolar perhaps optimized for low noise)

xrays might prove interesting

best
Paul

Show quoted text

----- Original Message ----
From: Fraser <fraser.castle@...>
To: loopantennas@...
Sent: Sunday, May 13, 2007 4:09:03 PM
Subject: [loopantennas] Re: RF Systems DX-One Pro MkII - Bi-Loop or not ?

            --- In loopantennas@ yahoogroups. com, Paul Birke <nonlinear@. ..> wrote:

Hi Fraser and Allsorry scratch all that I just transmittedthe 10 dB is the antenna alone  LOLoh wellPaul

Hi Paul,

Thanks for the input.

The DX-One base unit has unusual calibrations on the attenuator.

Instead of just showing the inserted attenuation it shows the system

gain.

The +10dB position is a straight through connection and is described

as +10dB because the antenna head is stated as having a gain of 10

dB. The 0dB position on the base unit is actually an insertion of

10dB attenuation. Theoreticaly in this position the input to the

receiver splitter is the same as the signal strength at the antenna

elements without any gain. This does not take account of feeder

losses though.

The base unit is a work of art. It's a very solid affair and contains

a low noise 28 Volt d.c regulated power supply, a calibrated stepped

attenuator, A MW filter and a high quality splitter. I bought a

couple of extra base units from Lowe(UK) last year for ?20 each. They

are easy to convert to 12V output and work very well with any phantom 

powered active antennas.

I will have to look out the X-Rays that I took of the Head unit

electronics as they may be of interest.

I note that the review that I refered to states that the DX-One

requires an excellent ground plane. I have the DX-One MKII and the

only groundplane requirement detailed in the instructions is for

static discharge purposes. The same is not true of my RFS DX-500

which requires an excellent groundplane to perform well.

Fraser

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[Non-text portions of this message have been removed]

Steve Ratzlaff

#3441

Hi,
I'm familiar with the circuits used in the head end of the older DX-1 Pro, and the receiver coupler/supply.
The head end is a basic high-impedance active whip antenna. The circuit is an exact clone of the old Ralph Burhans circuit he published back in the 1980's, using 100% negative feedback. That would account for one of the transformers noted by Fraser. The other transformer is very likely a common-mode choke on the output. My older unit did not have that common-mode choke; it only had the one feedback transformer. I'm guessing the "MK II" means the common-mode choke addition was the only improvement from the original DX-1 Pro.
The active power jfet device RF Systems is using has significant gate-source capacitance, which acts to shunt signals to ground the higher you go in frequency, and loss in sensitivity begins from about 12 MHz and up. They devised the very elaborate "egg beater" cage whip antenna in an attempt to improve the antenna capacitance, to offset the active device shunting effect. The bit in the advertising about reducing polarization effects is purely smoke and mirrors nonsense, and has no effect whatsoever on various signal polarization being received better with that cage whip antenna. There is no voltage gain for this active amplifier circuit, only overall loss from input to output.
The receiver coupler's "+10dB" input position is also a piece of fiction. That position directly couples the antenna's output through the various other parts (switchable BCB filter and dual-output splitter) to the output to the receiver. The other positions, "0" to "-40" are all switched attenuators before going to the BCB filter and splitter, with the "0" position being either -3 dB or -6 dB attenuation ( I forget which). The BCB filter is not designed for the NA BCB frequency range but for Europe.
The active device is very similar to the Crystalonics CP650 power jfet device that Dallas Lankford first discovered would work well in the old Burhans active whip circuit--it too has significant gate-source input capacitance. (This is the device the AMRAD active whip is using; they got their circuit from Dallas Lankford, who was never given proper credit in the article.)
I have been building and experimenting with active whip antennas for a number of years now; I've tested just about every commercially available antenna on the market, from either a hobby standpoint or from when my old company was building active antennas as a Defense Contractor. The DX-1 Pro is the only commercially available antenna that I've tried that I would recommend, despite its increasing loss of sensitivity as you go up the HF frequency range. However, it's very expensive for most hobbyists to even consider purchasing one. And any active antenna performs only as well as the local noise environment it's used in, and of course must be used externally from any dwelling with AC power. The farther from AC power you can mount such an antenna, either horizontal or vertical distance from AC power, the better it can work without being limited by local AC noise.
73,
Steve

Show quoted text

----- Original Message ----- 
From: "Fraser" <fraser.castle@...>
To: <loopantennas@...>
Sent: Sunday, May 13, 2007 4:29 AM
Subject: [loopantennas] RF Systems DX-One Pro MkII - Bi-Loop or not ?

Hi All,

A new question to ponder for the Group.

I own an RF Systems DX-ONE Pro MKII and have tried to establish
exactly what it is from the manufacturer.... they are staying
silent :-(

For those not familiar with the DX-One, it looks like a giant egg
beater and if you believe the sales blurb it uses a high performance,
very low noise overload resistant amplifier designed for the Dutch
Military. Yet another mystery amplifier design !!!!

I can vouch for the low noise element of the claim and it does
perform very well at my rural UK location with good rejection of the
house noise field.

What still mystifies me is exactly what it is in terms of antenna
type.

It looks like the Bellini Tosi crossed loop DF antennas that I used
to use on ships so I wondered if it is a crossed Bi-Loop to give
omnidirectional covereage ? I suggested this to the manufacturer and
received no response. It could be a compound monopole (folded up into
the diamond shape) but the antenna is ground independant and requires
only a safety ground for it's inbuilt ESD protection.

I have gone as far as X-Raying the antenna "guts" but that did not
reveal it's secret. there is a complex amplifier and several
torroids. One appears to connect to the "loop arms" and another is at
the output connector end of the amp.

I should be grateful for any comment that this groups members may
have on this antenna and it's design principle. Loop or Not Loop
antenna, that is the question :-)

I will post a picture of the DX-One in the photos area of this group
for those who do not know of it.

Fraser

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Steve Ratzlaff

#3442

As a postscript to the RF Systems DX-1 Pro active whip antenna comments I made, WRTH did an extensive review of various active whip antennas perhaps 5 or more years ago. The DX-1 Pro was clearly identified as an active whip antenna then, and was one of the antennas reviewed--it had a good review rating. The newer "MK II" apparently is a recent variation of that same active whip antenna. Perhaps the addition of a common-mode choke on the output of the whipamp is the only change, as I suggested in my previous post.

73,
Steve

Fraser

#3443

--- In loopantennas@..., "Steve Ratzlaff"
<steveratz@...> wrote:

Hi,
I'm familiar with the circuits used in the head end of the olderDX-1 Pro,
and the receiver coupler/supply.
The head end is a basic high-impedance active whip antenna. Thecircuit is
an exact clone of the old Ralph Burhans circuit he published backin the
1980's, using 100% negative feedback.(SNIPPED)


Hi Steve,

Many thanks for that superb description of the DX-1. You have made
my day as I have been scratching my head about this antennas design
for ages.

When I X-Rayed the mast section it had four wires interconnecting
the various 'loop' arms but I couldn't be sure how they were
connected. They certainly are not all wired in parallel in the MKII.
I was wondering if they had wired the 'loop' arms in series to
effectively compress a long whip into a small space. This bit of the 
design still eludes me.

As for the amplifier... your information is invaluable. The MKII
amplifier is stated as providing 10dB gain whereas the MKI was
spec'ed at 6dB gain. The issue of input capacitance is very
interesting indeed. I have some NOS Motorola high power jFETs (or
tFETS ?) that were used in some Watkins Johnson amplifiers that I
maintained. I suspect that these will also exhibit higher than
desirable input capacitance so I will re think using them in any
antenna designs that I build.

Thank you for your excellent help with this question Steve. It does,
however, lead me to wonder about RF Systems performance claims. RFS
make the MLB1 and this has caused much discussion both positive and
negative. I like their AA-150 that was built for the Lowe HF-150 but
it may be no better than any other active whip on the market. It is
well built though. The DX-10 is basically an AA-150 in a different
shell. As for the passive HF magnetic whips and some of their other
exotic designs, I am not sure that these are not just well
engineered 'snake oil' antennas. I own an RF Systems DX-500 which is
beautifully constructed and claims to work upto 500 MHz. I have
found that it needs an excellent groundplane for HF work and is
really just an RF probe (it has an extremely short active element).

Oh well.... it looks like the DX-1 is just an exotic & expensive
active whip pretending to be a loop then :-(

Thanks to everyone for their input on this topic. I'm off to start
saving for a Wellbrook ALA1530+.

Fraser

#10160

Hi Fraser

?

just once more browsing thru DX-one threads...: apparently you are in possession of Xrays! Could you please forward copies to my email address ulrich.ruch@.... My headamplifier has been laying around defective for more than one year, and all my queries at RFS remained unanswered. I would therefore ?like to have it repaired by some local - but for this I need to know how to get access to the amplifier?resp. how disassembly is made without causing any damage to the rest of the antenna stub.

?

Looking forward with keen interest to Hearing from you.

?

73s and happy New Year

Ulrich Ruch

Hinterester 13

CH 8184 Bachenbülach

#10163

I had a DX-One (MK2) for about two years.? It worked very well but my HOA made me take in down and I ended up selling it.

1) It is ABSOLUTELY an omni-direction vertical.

2)? It was the best vertical I had ever used and I had most of them.? I now have a DX Engineering active whip because it is lower profile.? I would say it has 80%+ of the performance of the DX-One at 25% of the price.? Where the DX-One REALLY excelled was in the LW band where reception was significantly better than with any other antenna I ever used.

3) I seem to recall that the developer (and President) of RF Systems died earlier this year.? My understanding was that the company was no longer in business though it seems Universal Radio still carries their products.

73, and Happy New Year,
Ian Meyers
Boynton Beach, Flroida

johnnyc604

#10165

Ian,

Did you by any chance have a Wellbrook 330S or 1530S in the past collection of antennas you could compare the RF Systems to?

Thanks,

John

Show quoted text

--- In loopantennas@..., <ihmeyers19@...> wrote:

I had a DX-One (MK2) for about two years.  It worked very well but my HOA made me take in down and I ended up selling it.

1) It is ABSOLUTELY an omni-direction vertical.

2)  It was the best vertical I had ever used and I had most of them.  I now have a DX Engineering active whip because it is lower profile.  I would say it has 80%+ of the performance of the DX-One at 25% of the price.  Where the DX-One REALLY excelled was in the LW band where reception was significantly better than with any other antenna I ever used.

3) I seem to recall that the developer (and President) of RF Systems died earlier this year.  My understanding was that the company was no longer in business though it seems Universal Radio still carries their products.

73, and Happy New Year,
Ian Meyers
Boynton Beach, Flroida

#10167

Unfortunately not John.? I do have a Pixel Pro 1B now.? No comparison, the DX-One was WAY better.? In fact I think all in my DX Engineering Active Vertical is better than the Pixel as well.

Maybe I am just lucky because this is a pretty low noise QTH but here at least the only thing I get out of the Pixel is directionality and that's just on BCB.? The overall signal levels on the Pixel are a few db lower than the vertical on anything above say 3 MHZ.? Not awful / unreadable but lower than on the vertical and of course there is virtually zero directionality on skywave.

I guess if you lived in a noisy environment a loop would be much more beneficial but it hasn't been here,? Perhaps a Wellbrook would be better but there seems to be no consensus on that.? Guy Atkins' tests point to the Wellbrook, Jack Smith's to the Pixel and both of those guys are knowledgeable, creditable sources so maybe its a QTH specific thing.

JMHO.

73,

Ian

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Locked RF Systems DX-One Pro MkII - Bi-Loop or not ?

RF Systems DX-One Pro MkII - Bi-Loop or not ?