4 Jul 2013

Wellbrook LF RX Loop

A Wellbrook ALA1530 loop antenna for VLF-HF reception is now in my plans for the new QTH. This is not a low cost antenna - currently around £200 in the UK - but its performance is excellent judging by reports from people I know and reviews. It looks like the very best choice of RX antennas for the 136kHz and 472kHz bands where local noise can be a real issue. It does not need to be mounted high, just about 5m from the house. The photo above (linked from the Wellbrook site) shows the antenna mounted on a fence.

The technical specification speaks for itself: truly excellent OIP2 (+90dBm) and OIP3 (+49dBm) figures and a 1dB compression point of +28dBm in the Medium Wave band. It can stand a local field strength as high as 400V/m. As a loop, this antenna has a figure of eight pattern, so local noise sources can be nulled in many cases. It covers from 20kHz to 30MHz.

This looks like a good investment before the LF DX season.


Anonymous said...

"No tuning necessary or matching unit"

How does that work?

Chris M6CRD said...

LZ1AQ's loop amp design works very well at VLF with a BN-73-0202 substituted for the output transformer core. Also: www.vlf.it/easyloop/_easyloop.htm
The Wellbrooks are a nice, and a pleasure to use.
Good luck with your experiments Roger.

Anonymous said...

Roger - are you also looking for HF performance or just 500KHz and below? If the latter, the active loop shown on my site (VE7SL Radio Notebook) works very well on LF using an easy build Burhan's preamp. I can even send you the Mouser parts you need if you would like to try it.

Steve / VE7SL 73 and best of luck with your move!

Roger G3XBM said...

Thanks for the feedback and suggestions. As my requirement is essentially just 136 and 472kHz, I think a homebrew narrowband loop with a high dynamic range preamp may better suit my needs. Also, if it gets blown up with nearby RF I an then easily repair it. For VLF I already use this approach.

73s Roger G3XBM