[time-nuts] OT - Old Hatfield 2105 Step attenuator specs

Giuseppe Marullo giuseppe at marullo.it
Tue Jan 14 03:00:35 EST 2014


Alberto,
many thanks but I need just to "calibrate" (I should say invent) a 
S-Meter for a BITX20a QRP Radio, and possibly double check the 
sensitivity in some very relaxed way. My equipment:

- MiniVNA Pro with a 2 signal generators from approximately 0 to -60dBm 
(not clear if they have an additional 12 or 18 dB attenuator inside). 
Obviously it is not calibrated nor checked.
- The 2105
- Dummy load and VNA calibration set (short, open and 50Ohm dummy load)
- several SMA/BNC adapters (probably not enough ones)

I need the typical -73dBm and something in the -112dB range to be 
satisfied. I don't know if and how much the MiniVNA is accurate, I 
should ask some ham in ARI to double check it.

Toto I have a feeling we are not in Agilent anymore...

Giuseppe Marullo
IW2JWW

On 1/10/2014 4:50 PM, Alberto di Bene wrote:
> On 1/8/2014 11:13 PM, Alan Melia wrote:
>
>> /Hi Alberto it is quite interesting to continue that test with no 
>> attenuator
>> but the shells of the coax plugs connected together. I would guess 
>> with the
>> gear you have the resultant would be at least 120dB down........but 
>> this is
>> not the case for all signal generators!/
>
> Hi Alan,
>
>   quite true. I performed the test you suggested, using as generator a 
> Rohde&Schwarz SMDU
> that has a calibrated output down to -140 dBm, so it must be well 
> shielded...
> I used 10 MHz as frequency, and, given that the settings of this forum 
> do not allow HTML (why ?)
> these are the links to the screen captures stored on my Dropbox account.
>
> As selective voltmeter I used the ELAD FDM-S1 receiver together with, 
> guess what... Winrad :-)
>
> This is what I see with the Hatfield attenuator set to its maximum, 
> i.e. 100 dB :
>
> https://dl.dropboxusercontent.com/u/15089947/hatfield-100dB.gif
>
> Setting it to 0 dB gives this result :
>
> https://dl.dropboxusercontent.com/u/15089947/hatfield0dB.gif
>
> So you can see that the difference between the two measures is just 88 
> dB, not the theoretical 100...
> And it is almost all to be attributed to internal leakage of the 
> attenuator, because, excluding the attenuator,
> and just connecting together the two BNC shells, leaving the center 
> pin unconnected, gives this :
>
> https://dl.dropboxusercontent.com/u/15089947/hatfield-shells.gif
>
> So the Hatfield attenuator IMHO can be fruitfully used only if you do 
> not pretend from it the utmost
> precision at high attenuation settings.
>
> 73  Alberto  I2PHD
>
>
>
>
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