Date   

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

Simon
 

Ideally solder it on..but to try it out an electrical choc block thingy will do .( typically white or black small block with little screws in, used to join cables together in house wiring junction box etc..)

Re making the loop..Chris used am imaginative idea of a “hula hoop”. Just tape wire to it..(frame for loop needs to be non conductive.) so no good tapping wire and resistor to say an ali bike rim.


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

Chris Moulding
 

Hi Eric,

For the best dynamic range from the head amplifier it is best to feed the amplifier with 12V via an unamplified Bias T. The base unit running off 5 V USB also has an additional amplifier so this may be over-driving your receiver.

If you are using a 1m diameter loop it will be resonant as a full wave quad loop in the VHF FM band. Make the loop larger or smaller to move the resonant frequency.

Regards,

Chris


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

paul newland
 

Greetings
As the performance offered by this cardioide loop design is so attractive, I am pretty keen to have a go at constructing one.
However, I have a couple of issues that are holding me back. Firstly, I am electronically "challenged" (know nothing) and have never, to my knowledge even seen  a resistor.
Never mind the hands full of thumbs, how would one actually connect the resistor(s) to the wire?
Would an electrical block connector work, or do they have to be soldered together and if so, how does one avoid putting the connection under stress?
Any guidance would be much appreciated.
Best Wishes
Paul


Re: Noise antenna..

Simon
 

Hi Tom

This is not xmas lights but their outside lights..”up lights” on their exterior walls making their house look nice..

Been there for years, but getting worse as time goes by.

Will post a pic of them later..


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

Eric Inloes
 

So it seems that there is FM broadcast interference using the SDRplay Bias-T throughout the HF band but it goes away when i use the 12V Bias-T power inserter you include as an option. 

Any ideas as to what's going on here? 


Re: Tips to improve LAA+ Performance?

Eric Inloes
 

Hi all,

RG-58 is finally here and it appears that all the tweaks have improved HF somewhat.

HF conditions are poor now so i'll have to do some more testing.


Re: Noise antenna..

Tom Crosbie G6PZZ
 

Simon,

Local noise has got worse here too in the last couple of weeks due to the proliferation of exterior festive lighting. It’s probably made worse by interior lights adding to the fray.

I don’t know how you approach these neighbours without coming across like a misery guts. I doubt you’ll persuade anyone to turn them off. Not until January anyway.

Perhaps a leaflet could be created that explains just how much interference is being generated by these devices and dropped off at the offending households, with an offer to help reduce the problem.

 

You could also stretch and twist the power leads at dead of night  and break the power connections. Eventually you’ll hit the worst offender….

 

Tom G6PZZ

 

From: CrossCountryWireless@groups.io <CrossCountryWireless@groups.io> On Behalf Of Simon
Sent: 09 December 2020 20:20
To: CrossCountryWireless@groups.io
Subject: Re: [CrossCountryWireless] Noise antenna..

 

Nothing then???

ok update..have found source of noise..well almost..its either house A or B. Both directly opposite each other, Both have led up lights on side of house..about 70m sw of me..
will work out which house it is tomorrow..

so need a directional antenna with lots of “gain” compared to say cardioid loop and importantly with no real dx potential..( which also rules out cardioid loop,) to use as noise antenna.

need something that will not receive any dx as once passed though phaser will also null out dx!

any ideas?????

also, which maybe better..how to approach said offender and get them to replace led bulbs..or light sensor ( Which seems more appropriate as noise always there 24hrs a day.noise gets worse as lamps switch on..) 
I thinking tell them the truth, but also suggest interference slowing down their wifi?? I dont mind replacing bulbs etc myself, but I suspect that could be iffy..( legally.)

anyone been here before?? Advice..

thanks Simon 


Re: Noise antenna..

Simon
 

Nothing then???

ok update..have found source of noise..well almost..its either house A or B. Both directly opposite each other, Both have led up lights on side of house..about 70m sw of me..
will work out which house it is tomorrow..

so need a directional antenna with lots of “gain” compared to say cardioid loop and importantly with no real dx potential..( which also rules out cardioid loop,) to use as noise antenna.

need something that will not receive any dx as once passed though phaser will also null out dx!

any ideas?????

also, which maybe better..how to approach said offender and get them to replace led bulbs..or light sensor ( Which seems more appropriate as noise always there 24hrs a day.noise gets worse as lamps switch on..) 
I thinking tell them the truth, but also suggest interference slowing down their wifi?? I dont mind replacing bulbs etc myself, but I suspect that could be iffy..( legally.)

anyone been here before?? Advice..

thanks Simon 


Re: LAA+ Surprisingly good at VHF

paul newland
 

"Because I can I decided to see how the LAA+ performed at VHF when compared to a VHF/UHF discone."

We live around 156M above sea level and I have a good discone above our roofline with a CCW LAA+ mounted with centre about 1M above ground level, beside the house.
There is a local VOR at a distance of 11.5NM from here at 61M above sea level (and over the horizon from here there being hilly ground in between).
Nonetheless, I get a reasonable signal via the LAA+, but unsurpisingly a somewhat stronger one from the discone. (image of CCW reception attached).
However, comparing signal reception on airband when conditions permit, the LAA+ provides a markedly better cleaner signal compared to the discone, which is actually pretty good in it's own right.
So, given a fair shot, I reckon that you'll do pretty well with yours and even with the LAA+ at the bottom of the loop (obviously not ideal for it), I still get some local VHF Marine Band activity (with great clarity).
Best Wishes
Paul


Re: LAA+ Surprisingly good at VHF

Paul Sayer
 

I have a smaller loop at about 70" in circumference.  I can try that as well.


Re: LAA+ Surprisingly good at VHF

Paul Sayer
 

Thanks for your reply. Things to definitely try.

 One thing I have forgotten. The loop is connected via the uTune ports of my Yaesu FTDX1200. That introduces a bit more loss at VHF. Next weekend I will try a direct connection. 

Still very impressive considering the loop is on the ground and not in the air. Plus the cross polarisation loss.

Regards. 

Paul G0VKT 

On Sun, 6 Dec 2020, 17:02 Chris Moulding, <chrism@...> wrote:
Hi Paul,

Thanks for the feedback on your experiments at VHF with the Loop Antenna Amplifier +.

We specify the LAA+ to cover up to 150 MHz due to the low pass filter built into the head unit. In practice it will cover the marine band around 156 MHz with a few dB of loss.

There are two ways that you can improve reception of the VHF marine band with the LAA+.

The first is to check the polarisation of your loop. If the LAA+ is at the bottom of your loop then its horizontally polarised at VHF. For vertical polarisation you need to feed the loop from the side.

The second point is that at VHF the loop is acting as a full wave loop like a quad element. If you make the loop out of wire 1963 mm or 77 inches long it will be resonant on the VHF marine band.

If you try both these changes I'm sure that the loop antenna will out-perform your discone.

Regards,

Chris


Noise antenna..

Simon
 

Looking for ideas ( that i have not already tried,) for noise antenna to feed a phaser..in the attempt to null out a smpsu on 1845-1855khz..
this noise varies in amplitude and frequency depending upon time of day..it originates  from  atleast 100m away at about 210 degrees ( i think.)

I can not null it out enough on the BIG trx mag loop, but can on the active loop array.. Unfortunately until I build the extra loop and delay line the active loop is not suitable for working real  weak ssb on 160m from stateside. ( hence wanting to use the big loop.) The cardioid loop is no better..It has too low an output and also facing  nw will not null out the noise.

so to cancel out the noise on the big loop..

have tried different combinations of active loops..one was successful in that it received the noise same level as the big loop..( this ment did not have to reduce input ftom big loop into phaser, thus keeping sn ok.) BUT the loop in question was also hearing stuff I want to hear, so once feed though phaser cancelled it out!.. so no go..

so..miniwhip?? Short vertical.. OR out of the box thinking.
a.) use ( suitably connected) a street light very conveniently next to front garden hedge..?
B.) low iron railing/ fence around my front garden?
C.) 6m Ali pole holding up end of  dipole?

I like the street lamp  option..high impedance amp from street lamp against earth..

thoughts??

thanks Simon 


Re: Getting started...

Chris Moulding
 

I forgot to mention that 2 to 3m USB cables will work well with the SDR-4+ receiver. I used 2m long cables to test them in the workshop.

Regards,

Chris


Re: Getting started...

Chris Moulding
 

Hi Alan,

You need to install the driver so that the PC can control the receiver frequency.

The firmware in the SDR-4+ receiver is the same as that used in the SoftRock SDR transceivers and receivers written by PE0FKO.

He has a web page going into great detail about the firmware. About halfway down the page is a section "Install the PC software automatic". Follow that and it should install it on your Windows 10 PC.

Regards,

Chris


Getting started...

Alan Clark
 

Hi everyone. 

Just over a year ago, I bought a second-hand device on Ebay, which is labelled SDR-4+ HF/VHF receiver. It has a number on the side, which is 0350. All the seals seem intact. 

I'm one of those people who took up SDR/SWL as a hobby and started with the RTL-SDR and eventually bought a number of Airspy and SDRPlay devices. 

I followed whatever guidance I could find online to install this SDR-4+ and it always seemed to me that somehow the driver was not working properly. I could hear signals, but could not seem to tune it properly. In the end, I gave up and put it to one side. Now, I have an entirely new PC and I'd like to try once again to get it working. I am using Windows 10, x64 bit, with a good graphics card. I have installed HDSDR and it's working with an Airspy Discovery. I'm not so familiar with this software, preferring SDRSharp and SDR Console. 

Could someone please point me in the direction of up-do-date drivers and let me know if there is a recent online guide on how to get this thing going. 

I have one basic question. The device came with two short USB cables, with USB 'B' connectors for the device itself. I am using USB 'B' cables for other devices and I've found it convenient to use cables which are 2 and 3 metres long, so that devices can be located further from the PC and monitor, which, I'm sure you all know, are sources of a lot of RF noise. Can I expect that 2 and 3 metre cables will work OK with this device?

Many thanks

Best wishes
Alan Clark 



Loop Types

Keith Ballinger G0RQQ / VA2QU
 

I am considering the CCW VLF loop amplifier for monitoring LW and MW broadcast stations as well as the 472kHz and 136kHz amateur bands plus NDB beacons. This will complement my home-brew Wellbrook clone for HF.

However, I am a little baffled by the apparent choices for the actual loop itself. I have seen designs using a single turn of wire or metal strip, single turns of coax cable, single turns of coax with a short section of braid removed opposite the feed-point, double turns of coax, and Moebius loops (a single turn of coax with the centre conductor and braid transposed opposite the feed point).

Can anyone suggest where I can find more info on the advantages/disadvantages of each type, or alternatively suggest which would be the best for my application?

Regards,
Keith


Re: LAA+ Surprisingly good at VHF

Chris Moulding
 

Hi Paul,

Thanks for the feedback on your experiments at VHF with the Loop Antenna Amplifier +.

We specify the LAA+ to cover up to 150 MHz due to the low pass filter built into the head unit. In practice it will cover the marine band around 156 MHz with a few dB of loss.

There are two ways that you can improve reception of the VHF marine band with the LAA+.

The first is to check the polarisation of your loop. If the LAA+ is at the bottom of your loop then its horizontally polarised at VHF. For vertical polarisation you need to feed the loop from the side.

The second point is that at VHF the loop is acting as a full wave loop like a quad element. If you make the loop out of wire 1963 mm or 77 inches long it will be resonant on the VHF marine band.

If you try both these changes I'm sure that the loop antenna will out-perform your discone.

Regards,

Chris


LAA+ Surprisingly good at VHF

Paul Sayer
 

Because I can I decided to see how the LAA+ performed at VHF when compared to a VHF/UHF discone. 

My set up is an RSP2 connected to a discone at about 4m AGL. CCW loop about 1m AGL. RSP1A is connected to to the loop. I am by the sea in Kent with a clear view out to sea. I am at a static caravan, so the loop is surrounded by lots of metal boxes. Testing by listening to marine VHF. Coax similar type and a similar length

Expectation - Hear nothing using the loop

Result  - Hearing quite a lot.

Very surprised considering where the loop is mounted. 

Yes, signals are down on the loop and SNR is worse. I can't at the moment get the loop higher. Due to the generally short transmissions I haven't checked the loop pattern and nulls. The attached screenshot shows a Dover Coastguard broadcast. Left screen is the loop and the right is the discone.  I think the Tx is very close to me but don't know where.

Conclusion - Very surprised at the result as my expectations were low. More testing needed.

Paul G0VKT


Re: Loop antenna removal

Tom Crosbie G6PZZ
 

Keep that file handy Chris, I expect to be in a similar situation in the next 12 months. I’ll be starting from scratch, looking for permission to instal something.

 

Tom G6PZZ

 

From: CrossCountryWireless@groups.io <CrossCountryWireless@groups.io> On Behalf Of Chris Moulding
Sent: 30 July 2020 16:06
To: CrossCountryWireless@groups.io
Subject: Re: [CrossCountryWireless] Loop antenna removal

 

Hi Gordon,

Sorry to hear about your brush with officialdom. I have a relative who lives in a retirement flat and it's the same for her. Anything out of the ordinary or not easily understood is not tolerated.

I can send you a letter or an email explaining what a loop antenna is and how it works in Health and Safety terms.

What's best for you and email of a letter sent via the post?

For extra detail what type of receiver are you using?

Regards,

Chris


Re: Tips to improve LAA+ Performance?

Tom Crosbie G6PZZ
 

FWIW, I prefer UR43. It has less loss (a gnat’s whisker) and better screening than RG58 and I’ve been buying it from Henry Westlake for almost 40 years.

 

Tom G6PZZ

 

 

From: CrossCountryWireless@groups.io <CrossCountryWireless@groups.io> On Behalf Of Eric Inloes
Sent: 04 December 2020 08:29
To: CrossCountryWireless@groups.io
Subject: Re: [CrossCountryWireless] Tips to improve LAA+ Performance?

 

Hi David,

No, They weren't. It was 50 Feet of good quality RG-6 vs a short 3 feet run of RG-58. With that said on SDRplay RSPdx at 15 Mhz the noise floor changed about 10 dBm higher for the 50 Ohm coax. That seems like quite a large difference which lead me to buy 50 FT of RG-58.

To me high noise floor could also mean more signal...

I know RG-58 isn't the best coax but i figure for the frequency range of LAA+ it's okay. RG-8X and LMR is far more costly.  

It was mentioned awhile go poorly mismatched to 50 Ohm could cause high noise and IMD products. Maybe the case here? 

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