Date   

Re: New product...HF Antenna Isolator

Andy.g4vcn@...
 

Hi Chris,  I have a limited space for a vertical with radials.
I have seen a YouTube video of a chap using your HF antenna Isolator (I think) to feed a Ground Loop Radial replacement system.
Said chap mentions that theres an article in Radcom on the subject but sadly I don't have it.... Do you have a PDF you could make available?
Many thanks in anticipation Andy..


Re: Covid..and making phased loop antenna array..

Simon
 

Hi again..

Updates..

Re coupling from mag loop to rx loop array..

Sorted!! ( for now.)

Was playing around on 40m..testing directional array vs full size inverted v vs 40m big mag loop vs other rx loop..

Interesting..and rather good! Hearing yb ja zl on directional loop array and not on others..ok not strong..s5.. but better than in noise.

What i noticed was no coupling from 40 mag loop..( again very h q antenna.) 40 mag loop is also real close to rx array..but not in line.


With this in mind i rotated 160-80m mag loop from nnw to w..so now not directly inline with closest rx loop..( was 1m away, now 2m.)

Coupling gone..result!! Now background noise floor on rx loop array s1-2..hearing many more stations..all well above noise floor here in london..ie ok lz la ea9 iz9 etc..( depends upon loop array direction.) no dx on 160m this eve.

Also preamps seem to be rf ok..as in tx 400w from loop no blown up sdr or preamp.

CHRIS please make a passive delay line..to go with your new preamp..or atleast make one to play with.quite stunning..make it 4 directional..

Mag loop simon ( happy except for m in law.) pls wish her well if you believe in the god thing..she does (very very Irish.)...( afraid i dont.)

Her name is Theresa..

Thank you.


Re: Covid..and making phased loop antenna array..

Simon
 

Hi

From researching alot on this..shielded vs unshielded...

From what I have found..shielded..but this is for LF work..not hf..all aimed at 160-40m max.

As Chris says ..OUTSIDE grade cable only..solid copper wires only..( one can buy cu platted ali..its cheaper..but a no no.)

If you have zero common made interference on your setup then i dont see the point in changing..

Here at my qth the is difference is alot!

Been comparing my “ old “ 4 square loop ( coax) with the new phased 2x 4 square loops..( cat5e.)

Noise on cat5e loops 10ish db down.thats with them switched to omnidirectional..( to try to be fair.) the noise i refer to is local man made crap..the coax feed loop has ALOT of ferrite on it..

I live in high noise urban area..maybe in a quiet out in the sticks area no difference???

Nothing is perfect..the cat5e takes more work to setup..espically if one has to mod existing equipment....its fragile and the stupid little wires like to break!

As stated by me..I DO not care about hf..max frequency i use loops for is 7mhz..all i care about is reducing the noise pickup on my loops and now making directional and low angle..so regards to unshielded shielded that maybe is a preference one has to make..note one does NOT connect shield to preamp, leave floating at that end..(if you go that route.)

Nice interesting thread..

Simon..


Re: Covid..and making phased loop antenna array..

Chris Moulding
 

Hi Tom,

The ethernet cable I used and used to supply with active loop antennas was an outdoor grade unshielded cable. Normal indoor ethernet cable will not last long with UV and rain water.

i often used it laid on the floor or buried just below the grass.

Attaching it to a metal support structure doesn't have any effect as it affects both pairs of the twisted pair equally so if the cable is correctly terminated in a 100 ohm impedance it cancels out any interference or noise coupled from from the metalwork.

Any excess cable can be coiled up. We used to buy the cable in 305m drums. For testing I fixed connectors on each end to measure the cable loss and isolation between the twisted pairs. From memory the loss at 30 MHz over a 305m drum was 10 dB.

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Tom Seeger
 

I currently have 2 passive Lankford antennas and 2 active loop antennas. All are fed with quad shielded RG6 cable. I have the usual line chokes and ground rods etc. Due to their various locations I've buried 2 coax cables, 1 is hanging in the air from house to a tree, and another is tightly attached to my rain gutter and most of the way up a TV tower. I've never used ethernet cable for RF so I have some questions.
1/ Can it be buried directly under the grass top soil like RG6?
2/ Will attaching it to a metal rain gutter or tower affect its performance or induce noise?
3/ Chris Moulding's active dipole document recommends against shielded RJ45 cable. I'm mainly interested in NDB DX and lower HF reception, so would shielded ethernet cable be better in my case?
4/ If using a standard 30m pre-made cables do you just coil up the excess at the antenna or the shack?
Thanks in advance. Tom


Re: Covid..and making phased loop antenna array..

Simon
 

David

The -140 is with the powered preamps off, but with all the cables still connected..
This was done to see how much noise pick up the cable has..ie zero!

If i do the same but using coax it’s certainly not -140!!

With preamps on s1-3 noise ( last night.) This is east london qth.

Still defo getting coupling to main tx mag loop though..Not alot, but visable on sdr..

So looks like rx loops going to front of house..problem is one will be literally on side of house..not ideal..will test just one in front of house to check noise is ok..

All tests 160m..

Simon


Re: Covid..and making phased loop antenna array..

g13flat@gmail.com
 

Or just see if you can get some camo tape or scrim netting. 


On Tue, 5 Jan 2021 at 12:43, David Cutter via groups.io <d.cutter=ntlworld.com@groups.io> wrote:
Simon

I'm staggered by your results and you must have some local magic going on to get a noise floor of -140dBm, don't change a thing, you're in a sweet spot.

BTW if you can't hide your loops you could try some simple camouflage, eg light grey mat car paint primer with the odd splash of mat pale green or brown to break up the straight lines. If you can raise and lower it so it's not always visible, your neighbours can have little to complain about.

Good luck, I'm looking forward to the next episode on this channel.

David G3UNA


> On 05 January 2021 at 11:47 Simon <ohhellnotagain@...> wrote:
>
>
> Ahhhh so it does..
>
> Since i only interested in 160-40( max.) I have not seen this ..ie no losses noticable here.( cable  runs are shortish.)
>
> I shall carry on using the screen..zero common mode interference..dont want to upset that..
>
> Simon






Re: Covid..and making phased loop antenna array..

David Cutter
 

Simon

I'm staggered by your results and you must have some local magic going on to get a noise floor of -140dBm, don't change a thing, you're in a sweet spot.

BTW if you can't hide your loops you could try some simple camouflage, eg light grey mat car paint primer with the odd splash of mat pale green or brown to break up the straight lines. If you can raise and lower it so it's not always visible, your neighbours can have little to complain about.

Good luck, I'm looking forward to the next episode on this channel.

David G3UNA

On 05 January 2021 at 11:47 Simon <ohhellnotagain@gmail.com> wrote:


Ahhhh so it does..

Since i only interested in 160-40( max.) I have not seen this ..ie no losses noticable here.( cable runs are shortish.)

I shall carry on using the screen..zero common mode interference..dont want to upset that..

Simon


Re: Covid..and making phased loop antenna array..

Simon
 

Ahhhh so it does..

Since i only interested in 160-40( max.) I have not seen this ..ie no losses noticable here.( cable runs are shortish.)

I shall carry on using the screen..zero common mode interference..dont want to upset that..

Simon


Re: Covid..and making phased loop antenna array..

Ian Pawson G0FCT
 

Simon,
Your question is answered in the manual Chris has provided. The manual states:

"Following tests with different types of cable we don't recommend the use of shielded cable as the extra capacitance caused extra losses at higher frequencies."

73,
Ian G0FCT


Re: Covid..and making phased loop antenna array..

Simon
 

Hi Chris

Question

Why do you not recommend using of the screen in cat5e?

I am using..its screened at rx delay line controller/ psu / rx out to rig——- screen connects to passive delay line—— follows out to the preamps..BUT IS NOT connected at preamps..ie left floating..

I here at my qth in london have a genuine -140 dbm plus noise floor with preamps off..( measured on elad duo trx..sdr console software.) ie noise floor of rx..so no common mode interference induced.thats with circa 50m of cat5e running around garden and front room( much to Mary’s annoyance!)


I cannot see it getting any better with no screening..only worse..

Please explain why you recommend this..genuinely interested!!( every db helps!!)..i am not using rj45’s but hard wired in via screwterminals..( no rj 45 crimper to hand and no way of getting out to but one ..bloody covid self isolation!)


I am using very high quality german made cat5e..( ebay bargain.£20 for 300m!!..result!)

Also my preamps are grounded to rf gnd via copper stake..this is via diode protection and 100k resistor.( mainly for qro tx protection.) ( at input to loop on preamp.)
See diagram in email..

Stay well Simon


Re: Covid..and making phased loop antenna array..

Karl Thompson
 




On Mon, 4 Jan 2021 at 18:55, Craig
<topnut1@...> wrote:

Thank you Chris

On 1/4/2021 12:39 PM, Chris Moulding wrote:
Here is the Operating Manual for the HF Active Antennap i designed back in 2015 for the RSGB Noise Measurement program.

It has some information on the Cat5 cable wiring and the RJ45 connectors. Note in the manual the original connectors needed rounding slightly with a file. I later sourced a better cable gland that would allow a unmodified RJ45 connector through and still compress to make a watertight seal on the rubber sleeve on the cable.

The link to the Operating Manual is: http://www.crosscountrywireless.net/CCW_HF_Active_Antenna_Operating_Manual.pdf

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Craig
 

Thank you Chris

On 1/4/2021 12:39 PM, Chris Moulding wrote:
Here is the Operating Manual for the HF Active Antenna i designed back in 2015 for the RSGB Noise Measurement program.

It has some information on the Cat5 cable wiring and the RJ45 connectors. Note in the manual the original connectors needed rounding slightly with a file. I later sourced a better cable gland that would allow a unmodified RJ45 connector through and still compress to make a watertight seal on the rubber sleeve on the cable.

The link to the Operating Manual is: http://www.crosscountrywireless.net/CCW_HF_Active_Antenna_Operating_Manual.pdf

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Chris Moulding
 

Here is the Operating Manual for the HF Active Antenna i designed back in 2015 for the RSGB Noise Measurement program.

It has some information on the Cat5 cable wiring and the RJ45 connectors. Note in the manual the original connectors needed rounding slightly with a file. I later sourced a better cable gland that would allow a unmodified RJ45 connector through and still compress to make a watertight seal on the rubber sleeve on the cable.

The link to the Operating Manual is: http://www.crosscountrywireless.net/CCW_HF_Active_Antenna_Operating_Manual.pdf

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Craig
 

Chris,

Put me on the waiting list for the new improved LAA. Also I would like more information on the construction of the Cat5E feed line.

Richard

On 1/4/2021 11:25 AM, Chris Moulding wrote:
As David commented earlier we have been making active antennas using Cat5 for quite a few years.

As Simon has already found it has some very useful properties for HF use.

Cat 5 cable is a very elegant engineering solution consisting of four two wire 100 ohm impedance twisted pairs. The twist rate of each pair is slightly different to reduce the coupling between each pair.

The cable specification says better than 40 dB isolation between the pairs, in tests we measured over 50 dB. We also found that the unshielded version of the cable was better than the shielded for HF radio use with better isolation and lower loss.

In the active antennas we manufactured two pairs were used for DC power feed, one pair was used for RF and the fourth pair was spare or used for a second RF channel in the case of the Dual Polarisation HF Active Antenna. The secret to getting the best out of Cat5 cable was to correctly terminate each pair at both ends.

At present I'm looking at designing a very high performance loop antenna amplifier. The original Loop Antenna Amplifier was originally meant to be a better low cost alternative to the MLA-30 but due to customer pressure I improved it to become comparable in performance to the Wellbrook and Bonito antenna amplifiers.

With the new design I'm starting from scratch using the best amplifier devices, filtering, weatherproofing and Cat5 interconnecting cable. The first prototype is running with the expected performance improvements. I expect to have the first batch ready in a month or two.

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Chris Moulding
 

If I assume that I finish the PCB designs for the new loop antenna amplifier this week then I expect that the price point would be £90 for the head unit and a boxed bias tee unit, with 6 to 8 weeks for the first batch to be ready after extensive tests of a pre-production prototype.

Regarding performance data I had upgraded my test equipment to accurately measure the existing LAA+ IP3 figures. The IP3 figure of the new amplifier in now beyond my upgraded equipment!

Tom, If you are using a loop indoors you would be OK with the existing LAA+. The new amplifier is for those wanting or needing even more performance.

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Tom Crosbie G6PZZ
 

Well Chris, this is a great start to 2021. I’ve just about saved up enough for an LAA+. Are you able to commit to a price point, production date and performance data at this time?

I need to add a loop to my collection which for the near future will have to be for indoor use only.

 

Stay well OM and good luck with this new product.

 

73 Tom G6PZZ

 

From: CrossCountryWireless@groups.io <CrossCountryWireless@groups.io> On Behalf Of Chris Moulding
Sent: 04 January 2021 17:25
To: CrossCountryWireless@groups.io
Subject: Re: [CrossCountryWireless] Covid..and making phased loop antenna array..

 

As David commented earlier we have been making active antennas using Cat5 for quite a few years.

As Simon has already found it has some very useful properties for HF use.

Cat 5 cable is a very elegant engineering solution consisting of four two wire 100 ohm impedance twisted pairs. The twist rate of each pair is slightly different to reduce the coupling between each pair.

The cable specification says better than 40 dB isolation between the pairs, in tests we measured over 50 dB. We also found that the unshielded version of the cable was better than the shielded for HF radio use with better isolation and lower loss.

In the active antennas we manufactured two pairs were used for DC power feed, one pair was used for RF and the fourth pair was spare or used for a second RF channel in the case of the Dual Polarisation HF Active Antenna. The secret to getting the best out of Cat5 cable was to correctly terminate each pair at both ends.

At present I'm looking at designing a very high performance loop antenna amplifier. The original Loop Antenna Amplifier was originally meant to be a better low cost alternative to the MLA-30 but due to customer pressure I improved it to become comparable in performance to the Wellbrook and Bonito antenna amplifiers.

With the new design I'm starting from scratch using the best amplifier devices, filtering, weatherproofing and Cat5 interconnecting cable. The first prototype is running with the expected performance improvements. I expect to have the first batch ready in a month or two.

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Paul Newland
 

That's going to make the fur fly around here Chris!
Best Wishes
Paul



Virus-free. www.avast.com


On Mon, 4 Jan 2021 at 16:25, Chris Moulding <chrism@...> wrote:
As David commented earlier we have been making active antennas using Cat5 for quite a few years.

As Simon has already found it has some very useful properties for HF use.

Cat 5 cable is a very elegant engineering solution consisting of four two wire 100 ohm impedance twisted pairs. The twist rate of each pair is slightly different to reduce the coupling between each pair.

The cable specification says better than 40 dB isolation between the pairs, in tests we measured over 50 dB. We also found that the unshielded version of the cable was better than the shielded for HF radio use with better isolation and lower loss.

In the active antennas we manufactured two pairs were used for DC power feed, one pair was used for RF and the fourth pair was spare or used for a second RF channel in the case of the Dual Polarisation HF Active Antenna. The secret to getting the best out of Cat5 cable was to correctly terminate each pair at both ends.

At present I'm looking at designing a very high performance loop antenna amplifier. The original Loop Antenna Amplifier was originally meant to be a better low cost alternative to the MLA-30 but due to customer pressure I improved it to become comparable in performance to the Wellbrook and Bonito antenna amplifiers.

With the new design I'm starting from scratch using the best amplifier devices, filtering, weatherproofing and Cat5 interconnecting cable. The first prototype is running with the expected performance improvements. I expect to have the first batch ready in a month or two.

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Chris Moulding
 

As David commented earlier we have been making active antennas using Cat5 for quite a few years.

As Simon has already found it has some very useful properties for HF use.

Cat 5 cable is a very elegant engineering solution consisting of four two wire 100 ohm impedance twisted pairs. The twist rate of each pair is slightly different to reduce the coupling between each pair.

The cable specification says better than 40 dB isolation between the pairs, in tests we measured over 50 dB. We also found that the unshielded version of the cable was better than the shielded for HF radio use with better isolation and lower loss.

In the active antennas we manufactured two pairs were used for DC power feed, one pair was used for RF and the fourth pair was spare or used for a second RF channel in the case of the Dual Polarisation HF Active Antenna. The secret to getting the best out of Cat5 cable was to correctly terminate each pair at both ends.

At present I'm looking at designing a very high performance loop antenna amplifier. The original Loop Antenna Amplifier was originally meant to be a better low cost alternative to the MLA-30 but due to customer pressure I improved it to become comparable in performance to the Wellbrook and Bonito antenna amplifiers.

With the new design I'm starting from scratch using the best amplifier devices, filtering, weatherproofing and Cat5 interconnecting cable. The first prototype is running with the expected performance improvements. I expect to have the first batch ready in a month or two.

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Simon
 

Hi Tom

Neighbours and jobs worth council people ( in uniforms telling me to take down my antennas, on their own back without realising they had been up for over 4 years, so had to go away with tail between their legs types..) are funny people..

I get on really well with my neighbours, but sometimes I even think looking up at the antennas that maybe i ought not to put more up!! Lol

Still..i do not live in a conservation area..there are many phone masts within sight much much bigger than anything here..and bird boxes are about to be attached to new loops..lol ( really useful once occupied.)

Hopefully neighbour will allow loop into their back garden ( placed against fence and disguised..)
This will allow it to work better as well as lowering profile..
They owe us some favours so lets see..( Bangladesh family whom only us would speak to for a few years..sorted their kids schools out etc..) very nice people..

Keep well Tom and others. mag loop simon g0zen

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