The Boonton cables start to have high resistance in the shields, allowing signal ingress ion. The Boonton 91 is a tube model (The only schematic I have is for the 91CA). It has a 50K balance pot across the probe input, that is labeled as R49. It has a 22Meg resistor from each end, to one of the inputs.
Boonton makes a 100:1 divider to extend the range of their RF voltmeters.It is part number '91-7C 100:1 Voltage Divider Adapter'. Here is an example of one:
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-----Original Message-----
From: "xhfeng2002@... [hp_agilent_equipment]" <hp_agilent_equipment@...>
Sent: Oct 12, 2017 1:35 PM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] RF Voltmeter?
Michael,
I think you are right. From the spec, the Boonton 92 seems has better sensitivity than HP410C, I don't have neither Boonton 92 nor HP410C so I can't comment on which one is actually better. Instead I have a Boonton 91 and a HP410B, they use different diode probes, Boonton has solid state, HP has tube, both 91 and 410B are quite stable and has good consistence, their frequency range is about the same, up to 1GHz, my Boonton 91 is off a lot at the 1mV range, it could be caused by some leaking caps. The HP410B's lowest range is 1V, not quite as sensitive as the Boonton.
Henry
---In hp_agilent_equipment@..., <mike.terrell@...> wrote :
The Boonton 93 is a True RMS Voltmeter, usable to 20 MHz. Maybe he meant the model 92?
-----Original Message-----
From: "xhfeng2002@... mailto:xhfeng2002@... [hp_agilent_equipment]" <hp_agilent_equipment@... mailto:hp_agilent_equipment@...>
Sent: Oct 12, 2017 11:24 AM
To: hp_agilent_equipment@... mailto:hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] RF Voltmeter?
Is Boonton 93 more like HP3400, HP3403?
Michael A. Terrell
Michael A. Terrell
Michael A. Terrell