[Test-Equipment] rms voltmeter?

[eugene at hertzmail.com]

Wow! Thanks to several of you who sent me this info.

Now for the really big question. Could I get away with anyone one device
that will accomplish what these two devices accomplish? Could an HP3403C
do for both?

Eugene


-----Original Message-----
From: test-equipment-bounces at mailman.qth.net
[mailto:test-equipment-bounces at mailman.qth.net] On Behalf Of J Forster
Sent: Saturday, January 19, 2008 5:37 PM
To: Discussion of Electronic Test Equipment
Subject: Re: [Test-Equipment] rms voltmeter?

OK. Here's some decoding:

the first 5 digits of the model number are the CAGE code. Some are
listed
here:

http://www.bjg-design.com/designbook/codeid.htm

so:

28480 is HP, so  "AC Voltmeter 28480-400E" is can HP 400E.....  a very
common unit.
04901 is Boonton, so RF millivolmeter 04901-92B-S5"  is a Boonton 92B-S5

You should be able to fing the meter specs w/ Google.

Best,
-John


eugene at hertzmail.com wrote:

> Allow me to elaborate, because I may be asking for the wrong thing.
>
> I am working on restoring a URT-23D transmitter with T-827D exciter.
I
> wish to work through the various voltage checks in the manuals (navy
> manuals) because there is much troubleshooting to be done.
>
> For example, one of the tests is to measure the RF output into a dummy
> load in volts, and by (V^2)/50 to get power and compare this
measurement
> to the power indicated on the internal power meter. The meter used in
> this test is "Voltmeter 50423-3028B MOD 172"
>
> Another meter used in testing this rig includes "RF millivolmeter
> 04901-92B-S5" Tests for this meter are expecting outputs such as
480-750
> mVrms. This for example, is used to measure the output of the
frequency
> standard.
>
> And there is a third simply known as "AC Voltmeter 28480-400E" which
> seems to be used for low frequency measurements audio freq and lower.
>
> I have no idea what these meters are. I wonder if anyone out there
knows
> whether these are true rms meters or not.  It would be ideal (although
> probably not possible) to get one meter that can do everything I need.
>
> Any ideas what kind of meter would be useful for me?
> Thanks
>
> -----Original Message-----
> From: test-equipment-bounces at mailman.qth.net
> [mailto:test-equipment-bounces at mailman.qth.net] On Behalf Of David
> DiGiacomo
> Sent: Saturday, January 19, 2008 4:47 PM
> To: test-equipment at mailman.qth.net
> Subject: Re: [Test-Equipment] rms voltmeter?
>
> >I have an HP 410B that I am attempting to use to measure some rms RF
> >voltages in the HF range.  I think the unit is not working correctly.
> >Someone had "restored it" before I bought it and I think its all
> screwy.
> >At the moment, I don't feel like trying to figure it out or fix it.
> >
> >Can anyone recommend a more modern (but not too $$) that can provide
> RMS
> >voltage measurements into HF and maybe beyond? The 410B will do
700Mhz
> >which is nice, but I probably don't need that high.
>
> This is confusing, since the HP 410B does not make true RMS
> measurements.
> The manual says: "The AC portion of the instrument is a peak reading
> device, calibrated in rms volts".
>
> If you don't in fact need TRMS measurements, and don't need to measure
> low
> level signals, you might consider a simple DMM RF probe such as a
Fluke
> 85RF.
>
> For low level measurements, an HP 3406A sampling voltmeter might be
the
> cheapest option.
>
> You could also get a Boonton 92B, but make sure it comes with a
> working probe/sensor.
>
> If you do need TRMS, look at the HP 3403C, or get a power meter such
as
> an
> HP 432A.
>
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