Re: [amsat-bb] Drake 2880 power

[Don DeGregori <don1mh@xxxxxxxx>]

John
Good description of the Bias-T. Just thought it would be better not put a
hole in the case and run a separate wire up to the converter for power.
This of course is not a big deal,  but something to consider, I guess.
Got lots of input on this one!
73...Don

"John P. Toscano" wrote:

> Don DeGregori (W6RWN) wrote:
>
> > This is probably an old question, but what is an easy way to power
> > the Drake, if one does not have a satellite rig that puts power thru
> > the cable. I know one can do the mod and apply power through a hole
> > drilled in the case. Is there a cheap power inserter idea around?
>
> The Drake is probably going to require mods in any event, and the
> power feed mod appears to be relatively non-noxious, so I'm not
> quite sure why you hope to avoid it.
>
> Nevertheless, you did ask the question, and the reply above does not
> answer it.   Here's what little I know on the subject.  You will need
> to view the message in a fixed-width font to have any hope of being
> able to actually discern what I'm trying to "draw" in crude ASCII
> text characters...
>
>                    DC Blocking Capacitor
>                            ||
>                            \/
>
> IF Radio ====[coax]========)(========*=========[coax]==== Drake 2880
>                                      |
>                            C1        (
>                                       )  <== RF Blocking Inductor
>                                      (       (Sorry, couldn't figure
>                                   L1  )      a better way to draw it)
>                                      (
>                                      |
>                                     )|(  C2 - Feedthrough Capacitor
>                                      |
>                                +VDC Power Feed
>
> So I suppose one could lash up a tiny perf board, a couple of RF
> connectors on each end, and the requisite capacitor and inductor,
> and put them into a miniature waterproof aluminum box to insert
> the DC power onto the coax without affecting the IF radio.  And, of
> course, if the power inserter is in the shack away from the nasty
> weather, it doesn't have to be waterproof, but I imagine that an
> RF tight aluminum box is still greatly preferred over anything else.
>
> Sorry, I have no idea on the appropriate values of the components.
> I guess that the inductor should probably be of the same size and
> shape as the one removed from the 2880 by the power supply mod that
> you want to skip.  Find a drill bit that slips nicely into the
> center of the existing coil, and then wrap the same number of
> turns of magnet wire around the drill bit, and use that for the
> inductor.  The capacitor can probably be a 0.01 uF ceramic disc,
> but don't hold me to that.  (Anyone else got a better idea?)
>
> John Toscano, KB0ZEV
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