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Re: Topband: Bias Tee question

To: "topband@contesting.com" <topband@contesting.com>
Subject: Re: Topband: Bias Tee question
From: Dave Kirk <w6mqi@yahoo.com>
Reply-to: Dave Kirk <w6mqi@yahoo.com>
Date: Sun, 8 Jan 2012 19:47:03 -0800 (PST)
List-post: <topband@contesting.com">mailto:topband@contesting.com>
I must have put the wrong address in because non of my reply's to anyone  have 
shown up here oh well. Good ideas Frank I've got chokes and caps every where in 
my design hi hi, but I might  just toss the idea out for running  power cable's 
out to each preamp not as clean but easier.  I have 110v power real close to 
each antenna so getting power to each antenna isn't a real problem and voltage 
drop won't be a problem either.
  So far this project has been lots of fun I used W7IUV preamp design with my 
own pc boards they work great best amps I've used before I just need to finish 
the rest of the package and see how the whole system works.
 73 Dave


________________________________
 From: "donovanf@starpower.net" <donovanf@starpower.net>
To: topband@contesting.com 
Sent: Sunday, January 8, 2012 8:38 AM
Subject: Re: Topband: Bias Tee question
 
Dave,

Use a well over rated DC blocking capacitor, this is not an application to save 
a few pennies by using a marginally rated capacitor.

You should also use a choke to ground with a high current rating to protect 
your receiver if the capacitor shorts out.  A choke wound with #18 wire on a 
ferrite core will guarantee that your receiver won't be trashed if the 
capacitor fails.

Its a good idea to place capacitors in series with all three ports of a 
"magic-T" 3 dB splitter.  The ferrite cores in commercially made splitters are 
very small, if even a small amount of 60 Hz AC current flows through the core 
it will saturate causing intermod problems.  

In a multi-operator station, a bandpass filter should be installed to protect 
the splitter from strong signal saturation, also resulting in intermod problems.

You can avoid splitter intermod problems by building your own splitter with 
large ferrite cores, but you can usually avoid that by using bandpass filters 
and capacitors to protect the splitter from saturation.

73
Frank
W3LPL

---- Original message ----
>Date: Sat, 7 Jan 2012 15:08:48 -0500
>From: "ZR" <zr@jeremy.mv.com>  
>Subject: Re: Topband: Bias Tee question  
>To: "Dave Kirk" <w6mqi@yahoo.com>, <topband@contesting.com>
>
>It never hurts to have a DC block when Murphy is around.
>
>Carl
>KM1H
>
>
>----- Original Message ----- 
>From: "Dave Kirk" <w6mqi@yahoo.com>
>To: <topband@contesting.com>
>Sent: Saturday, January 07, 2012 2:42 PM
>Subject: Topband: Bias Tee question
>
>
>> I’m designing a multi element receive array which
>> incorporates the usual 0 deg hybrid
>> combiner, 180 deg phase inverter, and 2:1 transformer. I’m going to use 
>> pre
>> amps on the antenna elements and need to supply 12 volts to them via the 
>> feed
>> lines through a bias tee. My question is do I need to worry about 12v 
>> being fed
>> back through the combiner, phase inverter, or 2:1 transformer to my 
>> receiver even
>> though their not physically connected or should I put .01 cap on the feed 
>> line going the my receiver for
>> safety.
>>
>>
>> Thanks Dave.
>> _______________________________________________
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>
>> -----
>> No virus found in this message.
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>> 
>
>_______________________________________________
>UR RST IS ... ... ..9 QSB QSB - hw? BK
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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