[amsat-bb] Re: Recommendations for a good bias-t for 2M and 70 CM

Stan, W1LE stanw1le at verizon.net
Sun Apr 25 08:24:02 PDT 2010

Hello Mark,

For my SSB Electronics preamps, I use their DC injector with sequencer.
Model DCW-15 SHF,  for the 1.2 GHz mast mounted preamplifier.

For others I use a Down East Microwave DC injector.
  Like their model BT-H for 900 MHz.
It has a higher RF insertion loss at 2M, where it is not designed for, ~ 
1-2 dB

I believe DC injectors are also made by ARR and  SUHNER.

Some call them a bias tee, but they are still DC injectors/extractors.

They are a 3 port device, 2 RF ports for your frequency, one with DC, 
one without.
The third port is for the DC connection, either injection or extraction.
The 2 RF ports are capacitively coupled for the DC isolation.
The DC port is connected thru a choke directly to the RF port that needs 
the DC.
Not too hard to build, but the factory made connectored boxes are handy.

On one system I use the spare conductors in the AZ/ELcontrol cable for
polarization switching, PTT and DC power for the stuff on the tower.

My Yaesu G5400B only uses 6 of the 8 conductors in the control cable.
6 for AZ and 6 for EL = 4 spares.
2M pol select, 70cm pol select, common PTT (ground to TX), and DC power.
For signal and DC return, I use the big black conductor in the 8C cable.
You may consider another spare wire for signal return.

Stan, W1LE      Cape Cod      FN41sr


On 4/25/2010 12:14 AM, Mark Lunday wrote:
> I have the Bias-T units from Array Solutions, but these are intended for
> 160-6M (I presume because of component losses at higher frequencies).
> What are folks using to power mast-mount preamps?
> Mark Lunday	
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