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Author Topic: Masthead Pre-amp  (Read 20382 times)

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Budgie

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  • Posts: 82
    • Hebrides Weather
Re: Masthead Pre-amp
« Reply #30 on: May 06, 2012, 05:39:16 PM »
If you turn the pre-amp power off, do you see a difference in reception?

Dana

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  • Posts: 159
Re: Masthead Pre-amp
« Reply #31 on: May 06, 2012, 05:58:09 PM »
If I turn the pre-amp power off, I have no more contacts on My Flights list and my RadarBox doesn't receives any signal....

MW0CVW

  • Guest
Re: Masthead Pre-amp
« Reply #32 on: May 06, 2012, 08:24:48 PM »
Hi guys

I use the Kuhne 1090Mhz LNA and the bias tree and get great results.

You have probably checked the following already.

1.All N TYPE connects are fitted correctly to coax with no Short or open circuit connections.

2.Rf input on amplifier (from antenna) and output to the (Airnav box/bias tree) are connected right way around.

3.If you have a multimeter (Avo) check the current drawn by the bias tree and amplifier via coax,should be less than 200ma.

4.There are no coax relay in the amplifier, so turning off the 12vD.C to the bias tree will cause the amplifier to act as an attenuator and vastly reduce signal range.

Note:This has been done as coax relays depending on the type can cause signal loss at 1090mhz.

When I first tested my Kuhne LNA the local contacts (my flights number increased) but it took a good 24 hours for the polar antenna plot to update and show the increase in range.

Hope my thoughts and comments may help you in sorting your problem.

Kind Regards

Paul

MW0CVW

EGGP/EGNR

Dana

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  • Posts: 159
Re: Masthead Pre-amp
« Reply #33 on: May 07, 2012, 03:14:45 PM »
Hi Paul,

Thank you for your help,  problem solved...Seems that the reason was the power supply with more than 200mA. I am using a power supply wih less than 200mA now and the number of contacts icreased with about 20%, also better and constant signal.
All the best wishes and many thanks for your advices :)
Regards,
Dana

MW0CVW

  • Guest
Re: Masthead Pre-amp
« Reply #34 on: May 07, 2012, 03:26:40 PM »
Dana,

Very pleased you have located the problem to the Bias tree 12volt supply.

I use a convention 13.8V supply (12v d.c) which has a current capacity of 4000ma (4-AMPS).

Bit of an over kill, but the supply never gets warm as its running 24/7.

I never use switch mode power supplies as the are very RF Noisy, and effect other equipment located in the same room.

any questions please drop me a message anytime.

Kind Reagrds

Paul

MW0CVW

EGGP/EGNR