[R-390] OT - CX-1363/U test lead

[Stan Gammons]

Hi Charles,

Another list member sent me the same info from URM-25B manual.

Many thanks to both of you!


73

Stan
KM4HQE




On 06/12/2016 10:21 PM, Charles Steinmetz wrote:
> Stan asked:
>
>> I'm looking for a schematic of the CX-1363/U test lead.  I was hoping
>> someone on the list could confirm if this test lead is simply a .1 uf
>> capacitor @ 400 vdc between the input and output with a 510 pf
>> capacitor @ 500 vdc across the output to ground?
>
> Roy Morgan posted the following on 1/17/15:
>
>> In the URM-25B manual, I found this:
>>
>> 12. TEST LEAD CX-1363/U.
>> (See figure 2-17)
> >
>> a. The Test Lead CX-1363/U should be used for
>> making interstage receiver measurements. It consists of a 0.1
>> microfarad capacitor (C-601) in parallel with a 510
>> micromicrofarad capacitor (C-602) enclosed in an aluminum
>> case similar to the antenna simulator and fixed attenuator
>> units. One end of this case is terminated in a type UG-185/U
>> connector. Two 18" long clip leads extend from the other end.
>> The capacitor network is in series with the red lead, whereas
>> the black lead is grounded to the case.
> >
>> b. The capacitor network is inserted to protect the
>> attenuator (E-112) of the signal generator from accidental test
>> probing at points of B + potential and should always be used
>> when making interstage receiver tests.
> >
>> c. The reactance of the test lead capacitors should not
>> normally affect the accuracy of the meter (M-101) voltage
>> indication since, in most cases, the impedance at receiver
>> interstage measurement points will be high. It must be
>> realized, however, that when the CX-1363/U is used at test
>> points of low impedance (below 400 ohms) the meter
>> indication can no longer be depended upon to reflect the
>> actual signal voltage applied.
>
> See <http://mailman.qth.net/pipermail/r-390/2015-January/055118.html>
>
> NB:  The 510pF capacitor is in *parallel* with the 0.1uF capacitor, 
> from input to output, for better performance at higher frequencies 
> (above the self-resonance frequency of C-101).
>
> I am not bothering to post Figure 2-17.  It is just a poor photo that 
> adds nothing to the understanding.  But see the attached image of the 
> similar CX-2919/U test lead, as shown in Figure 2-18 of the URM-25F 
> manual.  The CX-2919/U uses just one capacitor, 0.047uF.
>
> A single 1kV ceramic capacitor anywhere from 0.01uF to 0.1uF should 
> work FB.
>
> Best regards,
>
> Charles
>
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