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Re: ICom 706 use on Sats



M. K. Hess (N3EAQ) wrote:

> How exactly would that work? I've been through the FT847 manual back an
> front and see no option for supplying 12V via the coax ??? Am I missing
 > something, or do you mean using a coupler and supplying the 12V via an
 > outside source (didn't seem like that's what
> you were saying).

Mostly quoted from the FT-847 manual:

Menu option 29 [VHF-AMP] and Menu option 30 [UHF-AMP] --

When set to [INT], the internal RF preamplifier will be used, with 
on/off control provided via the front panel's [RF AMP] switch

When set to [ANT], the internal RF preamplifier is disabled, and 12 VDC 
at 300 mA (maximum) will be sent via the (corresponding) antenna port 
for powering an external preamplifier.

Default setting: INT

If you desire to use both the internal preamplifier and a tower-mounted 
preamplifier, select the "INT" setting, then provide power to your 
tower-mounted preamplifier via a separate power cable.

My comment:  When the ANT setting is used, 12 VDC is sent up the coax. 
The preamplifier is assumed to have an RF choke on the output side of 
the preamp (i.e., the side that goes to the coax to the radio), which 
blocks RF but passes the 12 VDC in to power up the preamp.

73 de W0JT

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