[DSP-10] Noise Figure (finally) measured.

[Scott]

Here is one source of preamps, both kit and assembled versions...they 
are receive only, which means you will have to come up with relays to 
switch them in and out of the line (they are meant to be tower mounted)

http://www.downeastmicrowave.com/Catalog.htm#BM2M

Scott
N0EDV

Courtney Duncan wrote:

> Hey Mike,
>
> That's good news.  Your measurement is consistent enough with mine  
> that I believe my measurement and I don't think there are any gross  
> errors in assembly.  I've made hundreds of 2 meter contacts on the  
> thing, so I didn't really think anything was wrong -- but this does  
> explain why I sometimes can't hear guys who are hearing me pretty well.
>
> So, a good preamp is next on the list then.  Anybody have any advice?
>
> 73, Courtney, n5bf/6
>
>
> On Sep 6, 2008, at 10:07 PM, kd7ts wrote:
>
>> Hi Courtney,
>>
>> I measured mine at 11.5 db noise figure. That was just measuring at  
>> the antenna terminal. It is used as the IF for 10 GHz.
>>
>> Works fine.
>>
>> 73 Mike KD7TS
>>
>> At 07:55 PM 9/6/08 -0700, you wrote:
>>
>>> My noise source was built, works fine, and was calibrated at NoiseCom
>>> in May.  Today I finally got to measuring the receiver performance of
>>> the DSP-10.
>>>
>>> Using F = ENR / (Y - 1) with Y = (noise on) / (noise off) calculation
>>> did several measurements using several calibrated fixed attenuators  in
>>> the setup.  Also compared the direct measurement to one done with all
>>> of the amplifiers and the Bird wattmeter in line.  The results across
>>> all tests are consistent, about 12.0 dB, that is 4300 K.
>>>
>>> This is somewhat higher than I was expecting so I scrutinized Sabin's
>>> article and the equations and played with them in a spreadsheet until
>>> I decided they are probably right.
>>>
>>> I was expecting more like 600K - 1000K for this.  It's no wonder I'm
>>> not seeing EME2 as quickly as expected, even at 70 watts, but I'm
>>> wondering now how I ever saw anything at 7 watts, even with 10,000~
>>> seconds of integration.
>>>
>>> Certainly, a nice low noise preamp is higher on the list now.
>>>
>>> Continuing to investigate.  Anyone have any ideas?
>>>
>>> Courtney, n5bf/6
>>> _______________________________________________
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>>>
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-- 
Scott
http://corbenflyer.tripod.com/
Flying Corben Junior Ace - Building RV-4
Gotta Fly or Gonna Die