box for bias-T of LAA++


Juan - EA5XQ
 

Hi

@Chris, I have seen at you webpage (http://www.crosscountrywireless.net/loop_antenna_amplifier.htm) that Bias-T already comes with a box (I have got two from last two orders without it) , could you please let us know the model of the box in order to get it?

I have been looking at Farnell or RS but not the optimal size,

Thanks


Chris Moulding
 

Hi Juan,

I've been planning to post details of the box for the bias tee on the forum.

I'll scan the drilling drawing and post it later today.

Regards,

Chris


Tom Crosbie G6PZZ
 

This will be handy Chris, as I now have a second box to drill. Can you please remind me if there are any electronic differences in the Bias-T between the LAA+ and LAA++ versions. I’m currently running my LAA++ with the Bias-T from the LAA+. I’m currently investigating a swathe of broadband noise between 600kHz and 1200kHz. Between 1200 and 1700kHz, the noise is still there but to a lesser extent. My loop is made from 20mm copper pipe approx. 1m square. It is a cardioid type and mounted on a rotator. Rotating the loop does not affect the intensity of the pattern. I get a similar pattern if I switch my RSPdx to the longwire but it is lower in level.

I’m currently building the GM3SEK mains filter which was described in RadCom some years ago, and rewiring all my 12V DC accessories. Hopefully that will help with the problem.

 

I trust you are well.

 

Tom G6PZZ

 

From: CrossCountryWireless@groups.io <CrossCountryWireless@groups.io> On Behalf Of Chris Moulding
Sent: 21 March 2022 08:33
To: CrossCountryWireless@groups.io
Subject: Re: [CrossCountryWireless] box for bias-T of LAA++

 

Hi Juan,

I've been planning to post details of the box for the bias tee on the forum.

I'll scan the drilling drawing and post it later today.

Regards,

Chris


Chris Moulding
 

The only difference on the latest bias tee unit is the addition of 1k resistors across both BNC plugs.

This is to discharge any static electricity that may charge the internal capacitors to high voltages if the bias tee is connected to a high long wire antenna rather than one of our amplifiers.

There is a theoretical slight loss but it's not noticeable in use.

Regarding your interference problem if you can't direction find it with the loop it may be noise coming into your receiver from the electrical wiring.

If you can power your receiver, PC and loop antenna from a battery you can then switch the electrical power off in your home to prove whether it is inside your home.

Another option as it is in the medium wave band is to place a portable radio against all items like chargers, power supplies and domestic appliances to see if you can trace the noise source.

Recently I had a sudden increase in the noise level at home. It's usually very quiet as I have added ferrite cores to every wire here.

Using a portable radio I narrowed it down to an iPhone charger. It appears that the internal RF filtering had failed and it was radiating a very high level of RF noise down the mains cable even with the ferrite. It was tricky to find as all the electrical wiring was radiating the noise and it was only by disconnecting the charger that the noise cleared.

It was very satisfying to find the noise problem, even more so destroying the faulty charger with a sledge hammer!

Regards,

Chris



Simon
 

Hi Chris

I am in the same boat yet again..s9+20 across 160, been there a week..extends upto and beyond 40m but decreases. The cardioid loops can not remove it..

No idea where from as of yet, driven around my block with the ft100 on 160m.. nothing..so now time to start switching off everything ( same as you more ferrites here than in farnell warehouse.) but sure its not here..

So can’t wait to move to the sticks this year!

Can you pls send me a reeuest via paypal for the qro isolation transformer pls ( assuming you can get the cores.?)

Simon g0zen


WA8LMF
 

On 3/21/2022 2:12 PM, Simon wrote:
Hi Chris

I am in the same boat yet again..s9+20 across 160, been there a week..extends upto and beyond 40m but decreases. The cardioid loops can not remove it..

No idea where from as of yet, driven around my block with the ft100  on 160m.. nothing..so now time to start switching off everything ( same as you more ferrites here than in farnell warehouse.) but sure its not here..

You need to start hiking with an FT-817 or 818 on foot.   (That's actually why I got a Yaesu FT-818 "porta-luggie"  -- to track down noise on both HF and VHF/UHF).  It really works well on the AM mode on any band for hearing the nature of the noise.  On VHF especially, it's far easier to hear on AM, than on FM with the usual hand-held.  With EBL rechargeable lithium AA cells installed in the holder provided for alkaline cells with the FT-817/818, it will run for nearly 10 hours.  Downside is that the lithiums won't recharge in-situ in the holder that was intended for disposable alkaline cells.  You have to remove them and recharge in a separate charger provided with the batteries.



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Martin - G8JNJ
 

On Mon, Mar 21, 2022 at 06:12 PM, Simon wrote:
s9+20 across 160, been there a week
Hi Simon,

In my experience, if it that strong, it's generally something very close to home.

Drop your main breaker and see if it's still present.

Good luck,

Martin