[Test-Equipment] HP 200 CD

[Richard Knoppow]

----- Original Message ----- 
From: <kf9nz at juno.com>
To: <test-equipment at mailman.qth.net>
Sent: Saturday, January 31, 2009 12:00 PM
Subject: [Test-Equipment] HP 200 CD


>        A 200CD followed me home recently after being 
> abandoned.  It
> lights up and does produce tone, although I only had it on 
> for a few
> seconds to see if there was any smoke leaking out.   Can 
> anyone tell me
> the value of the three electrolytic caps C12-C13-C14 in 
> the P.S.?
> Also, what is a 5AR4 tube?  Obviously a rectifier, but I 
> have never heard
> of it.  Is there any common type replacement?    I suppose 
> a couple of
> silicon diodes would do the job if the 5AR4 quit anyhow, 
> but I'd just
> like to know.
>
> Frankf9nz

      There are better schematics on other sites. For 
instance 
<http://www.home.agilent.com/agilent/techSupport.jspx?pid=200CD%3Aepsg%3Apro&pageMode=MN&cc=US&lc=eng>
      There is also a manual at:

http://www.hparchive.com/hp_equipment.htm

      http://www.ko4bb.com/   has a schematic showing the 
replacement of the rectifier tube with solid state diodes.

     The 5AR4 in an indirectly heated (has a separate 
cathode) tube with rather lower voltage drop than is usual 
with rectifiers that use the filiment as the cathode.
     Beware that the 200CD went through a number of changes 
during its life. The performance was improved considerably 
in the later versions. My memory is that there was a pretty 
complete re-design at some point.

--
Richard Knoppow
Los Angeles, CA, USA
dickburk at ix.netcom.com