hp 403b DB meter

[Herbert Gillingham]

At a recent hamfest I purchased a HP 403 DB meter.On all ranges
the meter needle remains to full scale.The batteries are missing.
Can someone tell me the battery voltage? Any suggestions as to
why the meter is at full scale? Has anyone a schematic of this unit?
I have checked esr of cap as well as transistors.I would
appreciate any comments.Please make comments in news group or at
[email protected].
Many thanks herbert

 

[Michael A. Terrell]

At a recent hamfest I purchased a HP 403 DB meter.On all ranges
the meter needle remains to full scale.The batteries are missing.
Can someone tell me the battery voltage? Any suggestions as to
why the meter is at full scale? Has anyone a schematic of this unit?
I have checked esr of cap as well as transistors.I would
appreciate any comments.Please make comments in news group or at
[email protected].
Many thanks herbert

First of all, it is a RMS AC voltmeter that is also calibrated in dB,
not DB. It has ranges from .001 VAC to 300 VAC full scale, or -60 dB to
+50 dB. A lot of these types of meters require the batteries to be
installed for the power supply to operate properly.


<http://cgi.ebay.com/HP-403B-Transistor-AC-Voltmeter-Op-Service-Manual_W0QQitemZ7609899957QQ>
is a "Buy it now" listing for the original manual. The seller might tell
you what you want to know, or you can just buy the manual for about $22,
including shipping. Then you will not only have a schematic, but the
calibration data, too.