Jack,
I built the supply around 1992 & had the parts for a few
years from before. It really was the ultimate PS & I
could vary the voltage from around 5V up to 15V. it has a
crowbar circuit and the remote sensing unit and well, I
really went overboard making it (my transformer weighed
at least 80 pounds and the heatsink was liberated from
the Navy) but it worked exactly as planned. I digress...
I just looked in my library and if you have the 1984 ARRL
handbook, you'll find the schematic I started with on
page 5-19 under the heading "A 300- to 400-Watt 12 volt
supply.
The 84 handbook has a blue cover. I remember the one I
used had a gray cover so this schematic is in several
handbooks. It was not in the 78 handbook though.
I just don't have the parts any more or I would have
built this instead of buying this new Astron for the K3.
The Astron is an excellent supply (albeit sans remote
sensor), I just like making things myself.
Once the warranty is up on the Astron, I will likely
piggyback a remote sensor in it, that was a truly nice
feature.
Gary
KA1J
> Hi Gary,
> I like your idea of the remote sense for your Astron. Can you send me a
> reference for the article in the Handbook? I just looked through the
> 2008 Hanbook in the power supply section and did not
see same.
>
> 73 and thank you,
> Jack, W3TMZ
> ----- Original Message -----
> From: "Gary Smith" <[email protected]>
> To: <[email protected]>
> Sent: Tuesday, January 27, 2009 11:14 AM
> Subject: Re: [Elecraft] K3/100 and the PSU
>
>
> >I used the included power cable and did notice a drop in the voltage
> > of about a volt. I had bought a "35" amp, 25 amp continuous Astron
> > power supply which has variable voltage but does not include a remote
> > probe as the one I made from the ARRL handbook offered. The probe was
> > used to ID voltage drop and the PS responded by upping the voltage as
> > needed so 13.8 would be at the rig at all times.
> >
> > Using that probe with my old TR7 kept the voltage dead on at the rig.
> > I was saddened to have left that in Indiana as a gift to a friend for
> > the PS components were made from an old Wang computer I canabalized
> > in the 80's and I designed it for an easy 80 amps and it weighed over
> > 100 pounds and was on casters. It was too much to move and is in use
> > today by my friend but I digress;
> >
> > I felt the best option with the K3 and the Astron VS35M was to use a
> > different power cable so I cut the cable aproximately 5" from the
> > Power Pole and soldered that short end to an 8 gauge cable made of
> > very fine wire which I bought from Home Depot. This was part of heavy
> > cable at about $5/foot with four conductors and a heavy neoprene
> > outer jacket.
> >
> > I stripped the jacket, used two of the connectors and attached a 4'
> > length to the Astron & k3.
> >
> >>From the K3 internal volt meter it reads:
> >
> > 14.0V at idle:
> >
> > At 25W the drop is .2 = 13.8
> > At 50W the drop is .3 = 13.7
> > At 75W the drop is .3 = 13.7
> > At 100W the drop is .4 = 13.6
> > at 120W the drop is .4 = 13.6
> >
> > Not as regulated at the rig as my old homebrew PS but certainly a
> > very little voltage drop. When running the amp I never use more than
> > 50W drive so I'm content.
> >
> > One caveat is I felt the need to devise a mount to keep the power
> > cord from moving around behind the radio. I know the PowerPoles are
> > loved by many but I see these smaller variety as a weak point and
> > don't much like them attached to the rig. The old TenTec attachments
> > were not as sexy as these PowerPoles but I felt they had more heft
> > and I didn't feel concern that someday the internal soldering would
> > come loose from repeated motion as the rig is located from one site
> > to another.
> >
> > Perhaps if the next larger size of PowerPole were utilized I would
> > feel it more sturdy?
> >
> > 73,
> > GAry
> > KA1J
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>
>
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