New LAA++ User

Michael Jackson

I bought one of the LAA++ kit and it arrived here in NZ in 10 days from the UK.

After unwrapping the boxes I connected the amp head to my rather large aperture delta loop and connected the antenna to my SDRPlay RSPDuo using the built in 4.7v Bias-Tee.  Initially it seemed OK but very shortly after, and by that I mean two or three minutes, I wasn't seeing any reception artifacts, no interference, signals or ionospheric sounders and indeed if I disconnected the antenna there was no change in the noise floor or reception.  Oh dear I thought!  So I set about using the 12v Bias-Tee that shipped woth the amplifier, same result, nada, zilch!  

After thoroughly checking my cabling and connectors I decided to open the amp head and check the PC board and indeed on the underside was a dry solder joint, sorry Chris I didn't take a photo, my bad.  A quick repair and 'lab test' with the 8ft loop and things looked more positive.  After putting the PC board back in the enclosure I connected the amp back to my loop and all seemed fine.  Except it wasn't!  Reception was OK but not fantastic, I could get better using the loop and my homebrew 9:2 transformer.

I then constructed a simple 1m loop out of RG6 coax and mounted it on a wooden cross frame, added the amp and 12v Bias-Tee and wooomppp!! up popped the signals a good 5 to 10 db stronger in SNR than my delta loop.  Happy days.

So with my RSPDuo I can run one tuner on the delta loop and the other tuner on the LAA++ to see some differences.  The LAA++ is certainly less susceptible to local noise and sounds a lot quieter than the delta.

All up, apart from the QA slip up, the LAA++ is certainly going to be a 'go to' antenna for me.

Chris Moulding

Hi Michael,

Thanks for letting me know about the problem with the LAA++.

We follow the NASA spec for soldering using 60-40 solder rather than the EU one.

Each amplifier board is tested when built and also after assembly on air with a loop and the bias tee it's due to be shipped with.

Even doing that it's still possible for the odd problem to slip through so I'm sorry for that and I'm happy that you fixed it.

As you have found the LAA++ is designed to be used with small low impedance loops. The secret to it's performance is the isolation transformer and common mode choke isolating the loop element from any RF noise coming up the coax.