[evlatests] Bandpass Ripple in ea28, RCP, L-band

[Dan Mertely]

Will do.  We had problems with this some years ago & were
able to cure it by replacing the amp itself.  (The old
surplus, 1980's amp didn't have enough input to output
isolation.

We'll look at the current system & see if something has
changed since we re-installed it on ea28 last year.
-Mert

On 9/3/2019 2:42 PM, jjackson via evlatests wrote:
> Wes and I just had a chat about this and our chief suspect would be the 
> W8 RFI monitor cable that is connected to L-band on this antenna.  The 
> length is just too long for anything else to make sense on a single 
> polarization.  30 meters would be about right for the length of the 
> cable running down the antenna.  We'll have someone take a look at it.
> 
> Jim
> 
> 
> 
> 
> 
> On 9/3/2019 11:01 AM, Rick Perley via evlatests wrote:
>>      Bandpass solutions from my Cygnus A observations, taken in April 
>> and August this year show a strong bandpass ripple in RCP only, for 
>> antenna 28 and L-band.  The period of the ripple is about 4.6 MHz, 
>> corresponding to 30 meters if the cause is a reflection.  The problem 
>> was not visible in data taken in December last year.
>>
>>      The ripple pattern is strongly time dependent (both in its 
>> amplitude and phase), so is very difficult to calibrate out.
>>
>>
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