SV: [Premium-Rx] Antenna Couplers

[Karl-Arne.A.Markstrom at telia.se]

Hello all,

A small word of advice, learned the hard way, is to check the even order intermodulation
behaviour of any candidate for a wide-band amplifier intended for antenna multicoupler service.

Single-ended wide-band amplifiers usually have inferior even-order IM than most premium receivers, 
even if they show very good odd-order performance, and to stay out of hard-to-locate IM trouble
especially when using large wide-band antennas it is advisable to use some form of balanced circuit.

The best performers in my experience have been the balanced Norton designs used in the Anzac AM-109,
the balanced preamps described by N6NWP in QST, and the DC coupled and heavy negative feedback
"totem-pole" design used in the Rodhe & Schwarz NV-14.

Would be interesting to hear of anybody's experience using the Mini-Circuits HELA high-dynamic range
balanced monolithic preamp as the wide-band amplifier in a HF multicoupler.

73/

Karl-Arne Markstrom
SM0AOM

=============================
Senior Radio Engineer
Maritime Networks
Telia Mobile AB Nacka Strand Sweden

Phone +46-8-6017171 
Mobile +46-706-636575
Fax +46-8-6017959 



-----Ursprungligt meddelande-----
Från: WF2U [mailto:wf2u at starband.net]
Skickat: den 10 november 2002 20:50
Till: premium-rx at ml.skirrow.org
Ämne: RE: [Premium-Rx] Antenna Couplers


About 10 years ago when I still making a living as an EE, I designed and
built an 8 port hybrid splitter array, with a preamp which made up for the
overall insertion loss, giving a net gain of around 2 db. The preamp I used
was one of the wide-band Motorola "brick" amplifier modules, (I think 100
KHz to 100 MHz,  the model number eludes me now, I have to look at my
coupler) with 1 W out  at -1dB. I also put  a 1.6 MHz high-pass filter at
the input of the  preamp as to minimize possible intermod from the broadcast
band. I forgot what the noise figure was, but it wasn't anything to be
significant on HF.
The coupler works very well,  I built it in a  4" x 6" cast aluminum box,
with an external 24 VDC supply built into a similar box.

73, Meir WF2U
Landrum, SC

 -----Original Message-----
From: 	premium-rx-admin at ml.skirrow.org
[mailto:premium-rx-admin at ml.skirrow.org]  On Behalf Of James C. Garland
Sent:	Sunday, November 10, 2002 1:25 PM
To:	premium-rx at ml.skirrow.org
Subject:	Re: [Premium-Rx] Antenna Couplers


Does anyone have a circuit diagram of an active multicoupler? I'd like try
and homebrew one, and don't want to reinvent the wheel.
Thanks,
Jim Garland W8ZR


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