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MLA-30+ Loop Antenna

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skyking_comms
Posts: 11
Joined: Thu Aug 20, 2020 10:13 am

MLA-30+ Loop Antenna

#1

Unread post by skyking_comms »

Decided to purchase the latest version of the MLA-30 loop antenna called the MLA-30+
Looks like the 30+ has improved performance above 11mhz.

I was wondering if anyone has modified it to include a BNC connection for better quality coax and added a better loop antenna?

I guess for the money it's never going to be a good as a Wellbrook or Bonito loop, but I'd be interested to see if anyone has successfully improved performance on the 30+

Thanks

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KA1GJU
Posts: 59
Joined: Tue Aug 11, 2020 2:16 pm

Re: MLA-30+ Loop Antenna

#2

Unread post by KA1GJU »

I purchased an LA1AQ amplifier board from Everett, N4CY:

https://sdr-radio.groups.io/g/main/topic/76232198#59499

Works very well with my ~1M diameter loop made from LDF4-250 hardline scrap lengths. Very directional via the nulls, so I am able to DF HF QRM on the farm here.
The hardline maintains is shape very well, supported at the top via a PVC Tee, and 1" grey electrical conduit PVC. The bottom of the conduit is where the amplifier is mounted and coax attaches.
Power is injected in to the feed line (power injector included with amplifier).

73 Kriss KA1GJU

skyking_comms
Posts: 11
Joined: Thu Aug 20, 2020 10:13 am

Re: MLA-30+ Loop Antenna

#3

Unread post by skyking_comms »

Good to see what other loops and boards are out there KA1GJU

I was looking at improvements people have made to the MLA-30+, looks like the first thing people do is put a BNC connector on the box with some people adding a clip on ferrite bead inside the box.

An aluminium loop of between 850mm and 1000mm overall diameter and between 15mm and 20mm appears to be optimum

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KA1GJU
Posts: 59
Joined: Tue Aug 11, 2020 2:16 pm

Re: MLA-30+ Loop Antenna

#4

Unread post by KA1GJU »

I was going to use a piece of CATV coax (~1/2") to make it light weight, but connecting copper wire to the aluminum jacket is always troublesome. The copper jacket of the LDF4-250 accepts solder VERY well, and thus makes a good electrical connection.

73 Kriss KA1GJU

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PD3LK
Posts: 235
Joined: Thu Aug 06, 2020 10:36 am

Re: MLA-30+ Loop Antenna

#5

Unread post by PD3LK »

Hi, most MLA-30+ mod's that i've seen are ok but until today i haven't see something that makes the loop realy better than it is.
I used alu strips to get a nice and sturdy 1mtr loop but the results are not much better. You just cannot get more out of the used video amp IC in this loop. In fact this loop (amp) is terrible below 1 Mhz and higher in the HF band. Google f.e. for the Norton Amps, they act much much better.

pauldbnut
Posts: 83
Joined: Wed Aug 19, 2020 10:59 am
Location: Dinosaur Country (IoW)

Re: MLA-30+ Loop Antenna

#6

Unread post by pauldbnut »

Not sure why you would expect to get much help here on MLA-30 nitty gritty.
The Facebook "MLA-30 Users and Experimenters Group" overflows with experience/suggestions.
Also try searching for YouTube videos on the MLA-30/BNC topic.
Paul White (Grumpy Old Git)

G6PZZ
Posts: 26
Joined: Sun Aug 16, 2020 6:05 am

Re: MLA-30+ Loop Antenna

#7

Unread post by G6PZZ »

Or loopantennas@ groups.io
Tom G6PZZ

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G4UCJ
Posts: 8
Joined: Mon Oct 19, 2020 10:59 am
Location: IO92ma
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Re: MLA-30+ Loop Antenna

#8

Unread post by G4UCJ »

Although I do not own an MLA 30, the idea of putting ferrites here, there and everywhere seems a sound one.
Just make sure they are the right mix for the frequency range in question. #31 and #43 are the usual ones to cover HF, but I think #77 (or #71) is the one to use for lower frequencies.

Certainly putting a large chunk of ferrite on the output to the feeder (or on the feeder itself, close to the feed-point) is a sensible move - to isolate the feed line and stop it picking up rubbish (ferrite at either end of the feedline is even better).

From what I can tell, the gain of the amp may be a bit high and can cause overload/images in lower performance receivers so having a gain control on the amp may be beneficial - as to where you can add one to the head unit, or if it would need to be at the receiver end I couldn't tell but the group already mentioned would be an excellent place to start.

Hope you get yours working to the standard you are looking for.

Stay Safe!
73, Sean - G4UCJ
QRA: IO92ma - W: www.hfradio.org.uk
TX: IC756pro + 2m transverter; Xiegu G90
SDR: Airspy: HF+ Discovery; Dual Port; R2; SDR-IQ; FCD Pro+
Ant: Active loop x 2 phased; 2m 5el @ 6m

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