[evlatests] Antenna 27B

[Rob Long]

I just had the guys replace the T304/T305 in 27B. Keith and I caught 
evidence that the output attenuator sometimes appears to change (with no 
effect to power) and sometimes changes with a corresponding change in 
power. It was suspicious enough to warrant changing so please let me 
know if this fixed the problem on 27B or not.

Thanks,
Rob

Rick Perley wrote:
>     Although others have noted this, and some others have seen the 
> evidence, I thought it useful to broadcast the following to a larger 
> audience:
> 
>     Recent data (since last night, at least) show that antenna 27, IF 
> 'B', is making large and abrupt changes in its gain.  The changes are 
> large -- in my 6cm data from last night, there were two changes, each of 
> 3dB.  The effect is seen in the power sum, power difference, and fringe 
> power.  Tsys is only slightly affected.  There is no significant phase 
> effect.  The bandpass shape clearly changes.   All this points to the 
> T304 attenuator changing. 
> 
> 
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