Active antenna

[Farty]

Does anyone use an active antenna for LF/MF/HF listening? What do you use, and how do you get on with it?

[Admiral]

Hi Fartblood, I built myself a PA0RDT active antenna, no big deal except I'm an electronics dullard and have eyes like Mr Magoo.

So I'm saying it's simple and cheap compared to the people flogging them on a popular online auction site.

It initially suffered from signal fluctuation, but some learned board member (can't remember who) suggested using a non-conductive mounting pole instead of a metal one, sorted.

Mine is most responsive up to about 12mhz, it works really well and is comparable with random long wires I've used over the years.

[Andy]

The Wellbrook ALA1530 loop. It's been up outside on a cheap rotator for at least 15 years without any problems. It's great for cancelling local noise and without it I'd be knackered on the lower bands. Only trouble is its response droops above 10 MHz and you are better off with a piece of wire on the higher freqs.
I've tried several 'active whip' and probe antennas, and while they are brilliant for their size I find they are *extremely* prone to local hash etc. Unusable around here.

[Farty]

Wellrbook looks nice bit is costly. One of the Nasa Marine or similar mini verticals any good?

[Mattylad]

I had an active antenna forced upon me at the rally yesterday, trader was sick of carting it around.
A 60hkz active antenna - it's in what looks like a 18" length of 38mm waste pipe with a BNC at the end and marked for 60khz.

I have no idea what to use it for so it may well just be "investigated"...lol

[Admiral]

Well, as you probably know, 60kc is the UK time signal for our 'atomic' clocks and watches.

[Mattylad]

After posting I took a walk to the car & bought it in.
Its an 100AN000A 60Khz Active Aerial by European Electronic Systems Ltd, inside is a PCB which then connects to a ferrite rod that slips into a big winding\coil.

I doubt I have anything capable of receiving MSF nor can I see any point in doing so - so it will likely be consigned to the cellar

[Admiral]

If it can take some RF then you could have some fun putting out a false time signal in your area, letting every atomic alarm clock go off 2 hours late.

***This is theoretical and should not be considered as a real project***

[Turbo]

Hi been using the wellbrook active loops for a long time use to have 4 of them they worked pretty good but they also picked up a lot of electrical noise and it took me ages to get the right height and distance from house sold 2 of of the loops with no regret but i have also been comparing them to my PK Loops 20/30/40 metre band dipoles and they honestly kill the wellbrook loops my main intrest is monitoring hf aircraft location is australia can hear every night from gander,new york,santan maria and early mornings from africa asia the way i see it if you monitor radio stations you can just run a piece of wire and you can hear lots of stations but monitoring aircraft from around the worls is a different ball game and for the price of 1 wellbrook loop can get 4 PK Loops Dipoles.

Regards Lino.

[Farty]

Cheers, I'll give them a nosey

[Andy]

Bloody Hell! After boasting about my lovely Wellbrook being in perfect nick after 15 years flapping in the breeze, I went in the shack this morning to find it was busted! I've checked everything out - cables, voltage up the coax, connectors, the lot. It just sits there drawing about 40mA (should be about 100mA) and only low-level sigs coming out. And of course the innards are all potted in epoxy. Gah!
As new ones are now about twice the price of what I paid for this, I'll build my own loop.

[Admiral]

Before you condemn it to landfill Andy, I can offer the postage and a couple of beers for it

[Farty]

I've had the Watson HF active job recommended to me. Anyone else use one? Watson gear is usually quite decent for the money.

[Andy]

Before you condemn it to landfill Andy, I can offer the postage and a couple of beers for it

You're a man after me own heart, Admiral. But I'll probably use the loop itself as the basis for a homebrew one.

[Andy]

Jobe done! I attacked the busted Wellbrook with a hack saw, removing the amplifier box and putting a gap at the top of the ally tube so I could use it as an earthed screen. A length of thick wire forms a single-turn loop element inside. A new conduit junction box containing an ugly-built long-tailed pair amplifier is at the bottom. All sealed up and almost identical to the original Wellbrook.
Seems to work well. MSF etc at the low end are good sigs and it tails off as the frequency goes higher, just like the Wellbroke. Will post some pics later if I remember.