[R-390] AN/URM-25s

[chacuff]

If the radio is so designed that RF can get out of various stages to the 
outside world those same weaknesses that allow the rf out will also allow RF 
in.  If your signal generator/cable is leaking RF it becomes a significant 
local RF source.  You may have the internal attenuator set to .001uv but you 
have a high level of RF going into that attenuator and if it's leaking to 
the outside world before being attenuated at some point you reached a point 
where the radio was detecting the leakage at a higher level than what you 
are pumping down the coax to the antenna connector.  Leading one to believe 
you have stumbled on the holy grail of hotness.  A receiver that is 
sensitive beyond dis-belief.  Reach up and disconnect the coax from the 
signal generator...are you still receiving the signal?  It's leakage....

Cecil
K5DL

----- Original Message ----- 
From: <wb5uom at hughes.net>
To: <n4buq at knology.net>; <r-390 at mailman.qth.net>
Sent: Thursday, March 01, 2012 9:06 PM
Subject: Re: [R-390] AN/URM-25s


>I could use some help understanding this too, Im just a lowly radio tech
>
> David / WB5UOM
>
>
> ----- Original Message ----- 
> From: "Barry" <n4buq at knology.net>
> To: <r-390 at mailman.qth.net>
> Sent: Thursday, March 01, 2012 8:37 PM
> Subject: Re: [R-390] AN/URM-25s
>
>
>>> For all of their good qualities, R390As
>>> are particularly egregious offenders -- they leak RF like a sieve, so
>>> ANY leakage from your sig gen will make them appear to have very high
>>> sensitivity.
>>>
>> <snip>
>>>
>>> Best regards,
>>>
>>> Don
>>
>> I don't understand how the radio leaking RF determines whether a leaking
>> generator will get into the radio.  I understand that a leaking generator
>> can get into the radio but don't see what the radio leaking has to do 
>> with
>> it.  Is it because if the radio leaks, then there's a path for RF in
>> either direction?
>>
>> Sorry, but the way that's worded, it just doesn't quite make sense to me.
>>
>> Thanks,
>> Barry - N4BUQ
>>
>>
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