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From: Jasen Betts on 7 Jul 2010 07:59
On 2010-07-06, W. eWatson <wolftracks(a)invalid.com> wrote:
>
> Somewhere I came across a setup for a simple "itty bitty" radio
> telescope a number of years ago. Its purpose is educational. Basically,
> it consists of a discarded 18" dish, power supply, and a satellite
> signal finder. I happen to have a Channel Master 1004ifd finder, but it
> gets its power from the LNB, which apparently gets it from a satellite
> rcvr. I have no rcvr. I'm looking for a way to power it.

13VDC up the coax, center positive.

> WEll, lucky me. A small amount of Googling got me to
><http://www.aoc.nrao.edu/epo/teachers/ittybitty/procedure.html>
> I'm not sure our local The Shack has a choke. I may have one. My LNB is
> different than the one in the pic. It's a Eagle Aspen DTV32+. I'm sure I
> have a battery clip and 8 battery holder. This might do it. I didn't
> notice the Rx connector on my CM1004, but that is where the power goes.
> I may be set.

yeah, 12V may be enough, the connector is probably 'F'

> I constructed the battery pack in the link above, but w/o the coil. I
> plugged it into the 1004ifd and immediately got something of a single
> note noise from the device. This seems wrong. Any ideas? I did not
> connect to the LNB and disk.

with the input open circuit unloaded and the output shorted it could be oscilating,
or that could be the base level tone.


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From: Jasen Betts on 8 Jul 2010 05:44
On 2010-07-07, W. eWatson <wolftracks(a)invalid.com> wrote:
> On 7/7/2010 4:59 AM, Jasen Betts wrote:
>> On 2010-07-06, W. eWatson<wolftracks(a)invalid.com> wrote:
>>>
>>
>>> I constructed the battery pack in the link above, but w/o the coil. I
>>> plugged it into the 1004ifd and immediately got something of a single
>>> note noise from the device. This seems wrong. Any ideas? I did not
>>> connect to the LNB and disk.
>>
>> with the input open circuit unloaded and the output shorted it could be oscilating,
>> or that could be the base level tone.
>
> Thanks. So I should put the choke in and connect the LNB? Yes, F.

Yeah, the choke will probably help, for even better termination you could stick a 75 ohm
resistor (82 is probably close enough) in parallel with the choke and a 100pF capacitor parallel
with the battery. But that may not be needed,

Pointing the LNB arm of the dish (which point in the approximate
direction of the focus) somewhere in the general direction of the sun (during the
day) and you should get a big peak on the meter.

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