[Test-Equipment] rms voltmeter?

[Dave Brown]

Use any known good RF power meter for the power measurement- just 
convert the given voltages to power for cross checking.   Bound to be 
a commercial equivalent for the exact meter but not sure which it is. 
The two other instruments are probably the Boonton 92B RF 
millivoltmeter and the HP 400E AC voltmeter. Try BAMA for 
manuals/specs. (Clues in the type numbers)
DaveB, NZ

----- Original Message ----- 
From: <eugene at hertzmail.com>
To: "Discussion of Electronic Test Equipment" 
<test-equipment at mailman.qth.net>
Sent: Sunday, January 20, 2008 11:09 AM
Subject: RE: [Test-Equipment] rms voltmeter?


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.

______________________________________________________________
Test-Equipment mailing list
Home: http://mailman.qth.net/mailman/listinfo/test-equipment
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:Test-Equipment at mailman.qth.net
______________________________________________________________
Test-Equipment mailing list
Home: http://mailman.qth.net/mailman/listinfo/test-equipment
Help: http://mailman.qth.net/mmfaq.html
Post: mailto:Test-Equipment at mailman.qth.net


-- 
No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.516 / Virus Database: 269.19.7/1232 - Release Date: 
18/01/2008 19:32