[amsat-bb] Re: DC-feeding through Coaxial on PA?
jari.koivurinne at virpi.net
Wed Feb 28 09:11:55 PST 2007
Yes it is possible but You have to use 7/8" or similar coax that will carry
30A current without too much ohmic losses.
Or You can feed 50-100V DC and use switching power regulator up there
to lower the voltage. Line regulation is then better than feeding the power
at the low end. And You can use cheaper RG-213 cable instead.
But You have to build a switching regulator.
> -----Original Message-----
> From: amsat-bb-bounces at amsat.org
> [mailto:amsat-bb-bounces at amsat.org]On Behalf Of SV1BSX
> Sent: 28. helmikuuta 2007 15:03
> To: Amsat-BULL
> Subject: [amsat-bb] DC-feeding through Coaxial on PA?
> Hi all,
> just I wonder if is acceptable the power feeding of a mast
> UHF-linear (ie 100 W behind of Antenna)
> through the same Coaxial cable (200 ft) for RF-driving.
> Yes I know, it's a common method with mast Pre-Amps etc. But,
> when the RF-power input-driving of Linear is
> high enough, ie 20 W or more, is it safe & acceptable to feed the
> DC-power voltage together with
> RF-signal on a common Coaxial?
> Ofcourse in the input of Linear I will put the necessary
> "DC-block cap" & RF-chokes with additional
> components in order to separate high enough the DC-feeding from
> RF-signal and a High-Power "T-Bias"
> down in the Shack.
> However I wonderering... I don't like the "toasted" MRF transistors !
> Anyone has experience with that?
> Thanks in advance
> 73, Mak SV1BSX
> sv1bsx at yahoo.gr
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