Date   

Re: Loop Amplifier as a Wellbrook replacement

Alan Gale
 

At 11:20 16/12/2020, you wrote:


Hi Sean,

My ALA1530 failed as well a few months back with exactly the same issues, and I bought the
CCW Loop (VLF version) as a replacement. It worked fine using the Wellbrook interface to feed
the voltage up to it, and I even used the metal ring of the 1530 as the aerial. All I did was
cut off the old amp with a hacksaw and then drill a couple of holes in the ends of the metal
ring, and attached the flying leads from the CCW with a couple of self tapping screws, which
worked fine. If it wasn't coming down in buckets at the moment I would nip out and take a
photo of it.

I don't know if there is any advantage of using the CCW Bias T instead of the Wellbrook
interface, but I can't say that I have noticed any problems, as basically it's still feeding
the 12 volts up there to the amplifier.

It's working well anyway which is the main thing! :-)

Alan.





Hi everyone,

As I/we are still recovering from Covid, I have been looking at improving the receive only antennas here.

I have a CCW Active loop (the triangular, single output, version) about 6m up on a telescopic aluminium mast. The other antenna is a Wellbrook ALA1530 (about 12-14 yrs. old), which is located about 10m further way than the CCW and at about half the height, but this one is on a rotator.

 

Both worked really well on their own, or as part of as phased array via an MFJ-1026 phaser. However, a few weeks back I noticed the signals from the ALA1530 seemed to be a long way down on usual. I could still hear stations on all bands but the signal levels were very low, even with the HF+ Discovery. The CCW is still producing lots of signals so I am looking at a defective antenna.

All the usual test have been done, such as checking there is 12V at the output of the indoor unit and at the end of the feeder. The RG58 feeder has been replaced with a brand new run with BNC terminations (the old feeder had pl259s with BNC adapters and had been spliced together along its length a few years back, so was due for a change). This made no discernible difference.

The oddest thing I noticed is that the ALA1530 has lost its directionality! I can turn the rotator through 360 degrees and the signal remains constant (I tried this with the R4 LW signal on 198kHz, and various groundwave signals on MW). There are no peaks and most strangely, no dips/nulls in signal strength at all. The conclusion I have reached is the loop amplifier has died, or at least part of the amp has died.

I can't get out to do further testing at the moment, however I cannot think what else it could be. Have looked at the Wellbrook replacement amps, but at £110, they are a bit out of my budget.

I am thinking that the CCW Loop Amplifier would be a good fit for what I want to do (NDB to Upper HF).

Before I order one, there are a couple of things I want to check (I have seen some discussion about this recently so it might still be fresh in the mind:

I will be using, for the most part, the Airspy HF+ Discovery or HF+ Dual Port with the 'Wellbrook' and was wondering about the Bias T arrangement. Neither of those Airspy devices has a built in Bias T so I would need to use an external one. 

Would the Bias T that comes with the CCW loop amplifier be suitable (I'd be wanting to drive the loop amp with 12V for best IMD performance). I think the after effects of Covid are addling my brain as I can't work out what I would need!

Basically, I just want a loop amplifier that could be used in place of the defunct Wellbrook one and give similar (possibly better?) performance.

I don't know what is inside the Wellbrook indoor unit, apart from supplying 12V up the coax feeder so I doubt I could use that.

73, stay safe and thanks for any advice/guidance

Sean - G4UCJ

My radio website: www.hfradio.org.uk


Re: Loop Amplifier as a Wellbrook replacement

Ray G3NKL
 

Hi Sean,

Shouldn't be a problem but you will have to make connections from the Wellbrook to the LAA+. You might remember, the Wellbrook has leads coming out of the amp and connected to the loop with self-tapping screws. They might be corroded in after all those years,. You would need two short wires to connect the LAA+ to the loop.

You could still use the Wellbrook bias-t and power supply with the LAA+. The LAA+ works best at 12 volts.

I have two loops here, a Wellbrook and a home-made loop/LAA+. I feed 12 volts to both of them from a CCW low-noise power supply and a dc lead splitter (Ebay)

Ray
G3NKL


Re: Loop Amplifier as a Wellbrook replacement

Chris Moulding
 

Hi Sean,

Sorry to hear that you have Covid-19. I hope that you are recovering OK from it.

I know of several customers who have replaced a faulty Wellbrook loop amplifier with a Loop Antenna Amplifier + with similar results to the original amplifier if it is fed with 12 V from the Bias tee board.

I'm sure that you will get a report from someone who has done this.

Regards,

Chris


Loop Amplifier as a Wellbrook replacement

Sean - G4UCJ
 

Hi everyone,

As I/we are still recovering from Covid, I have been looking at improving the receive only antennas here.

I have a CCW Active loop (the triangular, single output, version) about 6m up on a telescopic aluminium mast. The other antenna is a Wellbrook ALA1530 (about 12-14 yrs. old), which is located about 10m further way than the CCW and at about half the height, but this one is on a rotator.

 

Both worked really well on their own, or as part of as phased array via an MFJ-1026 phaser. However, a few weeks back I noticed the signals from the ALA1530 seemed to be a long way down on usual. I could still hear stations on all bands but the signal levels were very low, even with the HF+ Discovery. The CCW is still producing lots of signals so I am looking at a defective antenna.

All the usual test have been done, such as checking there is 12V at the output of the indoor unit and at the end of the feeder. The RG58 feeder has been replaced with a brand new run with BNC terminations (the old feeder had pl259s with BNC adapters and had been spliced together along its length a few years back, so was due for a change). This made no discernible difference.

The oddest thing I noticed is that the ALA1530 has lost its directionality! I can turn the rotator through 360 degrees and the signal remains constant (I tried this with the R4 LW signal on 198kHz, and various groundwave signals on MW). There are no peaks and most strangely, no dips/nulls in signal strength at all. The conclusion I have reached is the loop amplifier has died, or at least part of the amp has died.

I can't get out to do further testing at the moment, however I cannot think what else it could be. Have looked at the Wellbrook replacement amps, but at £110, they are a bit out of my budget.

I am thinking that the CCW Loop Amplifier would be a good fit for what I want to do (NDB to Upper HF).

Before I order one, there are a couple of things I want to check (I have seen some discussion about this recently so it might still be fresh in the mind:

I will be using, for the most part, the Airspy HF+ Discovery or HF+ Dual Port with the 'Wellbrook' and was wondering about the Bias T arrangement. Neither of those Airspy devices has a built in Bias T so I would need to use an external one. 

Would the Bias T that comes with the CCW loop amplifier be suitable (I'd be wanting to drive the loop amp with 12V for best IMD performance). I think the after effects of Covid are addling my brain as I can't work out what I would need!

Basically, I just want a loop amplifier that could be used in place of the defunct Wellbrook one and give similar (possibly better?) performance.

I don't know what is inside the Wellbrook indoor unit, apart from supplying 12V up the coax feeder so I doubt I could use that.

73, stay safe and thanks for any advice/guidance

Sean - G4UCJ

My radio website: www.hfradio.org.uk

 


Re: Loop Types

Keith Ballinger G0RQQ / VA2QU
 

Thanks for the responses to my questions. It seems like there’s no one single answer and it’s a case of “try it and see.” Certainly it means it’s an area for experimentation. There is another person living a short distance from me who is also experimenting with active loops, so it provides a route for exchange of ideas.

Regards,
Keith


Re: Revised web pages

Elwyn
 

On 15/12/2020 10:41, Chris Moulding wrote:
There has always been a line on any of the web pages taking PayPal payments stating that VAT would be added during the transaction for UK and EU customers.
Originally the UK/EU payment option included VAT. Unfortunately some shall we say "cost conscious" UK customers tried to get around paying VAT by selecting the US/international shipping option without VAT instead.
We still had to take VAT out of the payment and the extra cost of the shipping charge didn't cover the VAT charge.
This was acceptable when it was just the odd mistake but I think the word got around and we started getting this on a regular basis.
As a result I made a list of countries within our PayPal listing (UK and EU) where VAT should be charged. VAT is then added during the transaction for those countries whatever option button is selected.
Regards,
Chris
_._,_._,_
Yes, I can understand that and also the reply of Bob G3REP. It was just that there wasn't any note on the screens I could see that said they were ex-vat, and that would be handled in the paypal process.

I'm sorry for sounding harsh but I have been caught out many times by companies selling stuff that don't mention vat until the payment area, and in one case it cost me hundreds in extra costs and I had to borrow money to afford it.

So yeah, there are unscrupolous people out there but being informed is half the battle and a lot of the stuff you sell is pretty unique too.

Cheers

Elwyn
2e0ELW


Re: Revised web pages

Chris Moulding
 

There has always been a line on any of the web pages taking PayPal payments stating that VAT would be added during the transaction for UK and EU customers.

Originally the UK/EU payment option included VAT. Unfortunately some shall we say "cost conscious" UK customers tried to get around paying VAT by selecting the US/international shipping option without VAT instead.

We still had to take VAT out of the payment and the extra cost of the shipping charge didn't cover the VAT charge.

This was acceptable when it was just the odd mistake but I think the word got around and we started getting this on a regular basis.

As a result I made a list of countries within our PayPal listing (UK and EU) where VAT should be charged. VAT is then added during the transaction for those countries whatever option button is selected.

Regards,

Chris


Re: Revised web pages

Bob G3REP
 

I think you will find Chris has cleared up that problem with his latest changes to the website with the UK departure from the EU.
EU prices are now ex-VAT

eg: VAT will be added during the PayPal transaction for UK (and EU orders up to 31 Dec 2020).

73s

Bob
G3REP


Re: Revised web pages

Elwyn
 

Can you make it more clear on your web page that your prices are all ex-vat?

I was with a friend ordering stuff last week from your site and we weren't informed about the tax on top until the payment method added a bit on top. Which was unexpected and annoying as it takes things out of budget a bit.

Even knowing that VAT was NOT included on the prices would have helped :(

Cheers

Elwyn


Re: Loop Types

paul newland
 
Edited

Hi Keith
May I offer a diffident input from a minnow in waters full of Pike, but FWIW I have the LAA+, which works very well for me. Chris has recently published a design for a cardiode loop (on here) that is very interesting indeed. However, I use the LAA+ successfully from 10 Khz upwards (attached is a screenshot taken this morning and a quick peek at the MK1 version of this complete with rotator - the wire has since been replaced with wire-rope) of what I believe is a reference signal at around 11.968 Khz and it is excellent in the NDB band using an inverted delta constructed using around 16' of galvanised steel wire, which may seem an odd choice, but has been used with great success by a knowledgeable DX enthusiast (I cribbed his design). It does perform outstandingly in the NDB department, outperforming my Wellbrook ALA1530LN, which is no mean achievement. I am able to rotate both and it is very directional. Obviously, in view of it's aperture size alone, it will probably perform worse than the Wellbrook the higher one goes in frequency (or so I understand). By the way the "Rotator" is just 5'1"...
PS: The wire in the background is a power-line!


Revised web pages

Chris Moulding
 

Over the last few days I've been revising the web site in preparation for the UK leaving the EU transition period on 31 December 2020.

It allowed me to look at the web pages and realise that some of the photos on the web pages are out of date.

The first one I've updated with a new photograph is our End fed antenna matching units page.

http://www.crosscountrywireless.net/end_fed_antenna.htm

More to follow...

Regards,

Chris


Re: Loop Types

Simon
 

Hi

I have tried many too..both on active loops and mag loops ( feed loop.)

My conclusions where..

Shielded vs unsheilded no difference at all..on mag and active.so not worth the effort of making shielded loop..

Below are comparisons of 1m dia wire loop on active antenna.( wire 3mm dia.)

Mobius on active loop..no difference or worse due to higher inductance
19mm copper tubing..big difference..19mm wins.lower inductance. Lf-30mhz.

Parallel loops of 12-19mm ..big difference..lf-30mhz.

Crossed parallel loops of 19mm or 12mm copper tubing ( each loop 1m square.) best by far..lf-30mhz..but now one has an array of 2x2 m so not small!

Cardioid loop..poor..needs adjustment of input matching into loop amp i suspect..too high inductance for loop amp..TOO be continued as not investigated loop enough yet..if can get loop amp working well with, will investigate phased array of..
Another Issue with cardioid loop is poor nulling of noise compared to standard loop..but does have lower “ take off” angle..hence why further investigation required..However phasing two parallel non cardioid loops via delay line brings their “ take of” angle down to about 30 degrees..and they perform much better in regards to signal strength.( which matters as delay line plus combiner robs signal..) currently building adjustable delay line ( see lz1aq site.) to play with this..AND also phasing cardioid loops when i get the amps working well with..( as should get even lower angle “ take off”.

All above tested with ccw and lz1aq amps..all in urban high noise qth.

Simon g0zen


Re: Loop Types

Tom Seeger
 

Hi Keith. It is a bit confusing isn't it. I've done a few experiments comparing a Moebius loop to a 2 turn coax loop, both from RG-8 cable using an LZ1AQ style amplifier. To be honest, I couldn't find much difference between them. However compared to a single turn, signals below 500 kHz were up a bit. But both the Moebius and 2 turn loops were down somewhat above 6 MHz. So its a trade off. I have also tried single turn 1 mm wire vs 8 mm wire. I think I see a very slight improvement above about 15-20 MHz but its hard to say with changing conditions and a time delay for the change over from one 1 to 8 mm wire. Also played with shielded vs unshielded. I build a setup using RG-8 cable and toggle switches to rapidly change over from one to the other. Again the differences were subtle and in my location, with my type of local noise, I just couldn't tell much difference. So I'd say inconclusive. All of my experiments were with a 1.2 m diameter circular loop. Presently I've settled on a 1 m unshielded loop made from RG-8 using just the shield. All within PVC electrical conduit. Seems to be easy and effective. Hopefully others will chime in with their findings.
Regards Tom


Re: LAA+ FM broadcast interference using SDRplay Bias-T but goes away using 12v Bias-T power inserter?

Simon
 

Hi

No exactly the opposite..Ie more volts the better..( up to a point!)
No more than 13.8v though as more than that and I suspect goodbye transistor..

The gain may increase alittle from 5v to 12v BUT the strong signal handling capability goes up much more in relation to gain.

Do not use ccw 5v amplified tee though ( but at 12v.) a standard tee is all that’s needed.

I run mine at 13.8v from the psu ( fused and common mode choked.)

Simon


Re: LAA+ FM broadcast interference using SDRplay Bias-T but goes away using 12v Bias-T power inserter?

Eric Inloes
 

Hi Simon,

Ah, I figured more voltage would make IMD worse as it would result in higher gain. I guess that's not the case here.

Thanks clarifying that. 


Re: LAA+ FM broadcast interference using SDRplay Bias-T but goes away using 12v Bias-T power inserter?

Simon
 

Eric

Chris answered your question.

To help stop intermod from strong stations the amp likes 12v rather than 5v.

As you have noticed it goes away when using 12v..so may i suggest you use the 12v tee rather than the 5v from your sdr.

This is not a fault with the ccw amp but is down to how the amp works..it is the same with many high end loop amps..they need full working voltage to “ reject” interference from unwanted signals..all my loop amps run at 12v..

Some people can get away with using 5v. Some can not..

Regards Simon g0zen


Re: LAA+ FM broadcast interference using SDRplay Bias-T but goes away using 12v Bias-T power inserter?

Eric Inloes
 
Edited

Hi Chris,

Hum... 
In this case it's just 5V form the SDRplay Bias-T and it's not anything else. Is there perhaps something more going on here? 

I am using a 1m diameter loop of 15.8mm OD copper pipe.

Thanks! 


Web sdr for me till new year..

Simon
 

Some complete @&@8 has put up some ( i hope.) dodgy xmas lights..s9+ all across the bands.makes the existing smpsu noise look silly!

making yet another phaser..To phase this out??

i already hated xmas..anyone got some land they will allow a remote  sdr rx to be sited??

simon g0zen 


Re: How to make a cardioid loop with a Loop Antenna Amplifier +

paul newland
 

Thanks for the input Simon
I'm one step nearer now.
My present iteration of the loop is an inverted delta, which works very well for me, is pretty sturdy and non-conductive, so may the way for me to go.
Best Wishes 
Paul


Re: How to make a cardioid loop with a Loop Antenna Amplifier +

Simon
 

Oh i forgot to add..if buying resistors from ebay or wherever make sure they are NOT Wirewound type..

321 - 340 of 7768