[R-390] HP-11042A

[Roy Morgan]

On May 31, 2009, at 11:20 PM, Barry wrote:

> Can someone please tell me what's inside of an HP-11042A?

Information I have (a  list of  HP devices)  says:
"HP 11042A  probe T connector N (for 410 series - same as HP455A)"

and the HP 410 manual indicates to me that it s simply a line section  
(short coax  line - no capacitors from input to output) with the port  
for the 410 probe.  I can't put my hands on mine right now, or the  
similar ones I have made by some other company (see below for an  
explanation for what those might be), but I seem to remember a  
capacitor coupling the center conductor to the RF probe tip.

I found this in my notes file about the HP-410B:

> From: <dgsvetan at rockwellcollins.com>
> Subject: {Collins} Re: 302C-1 Wattmeter Calibration
> To: hmeyer at hvc.rr.com
> Cc: collins at listserve.com
> Date: Thu, 31 Mar 2005 12:29:48 -0600
>
> Herm,
>
> I did my homework last night and have got the information your  
> requested.
> Since several list members sent me comments about the overall 410  
> posting
> (thanks to all of you who replied), there may be others desiring the  
> same
> information.  So, here goes:
>
> The H-P probe to which I referred,  and which was used by the  
> military (as
> well as commercial entities) is:  HP Model 11042A Coupler
>
> The 11042A has a pair of Type N connectors, one each male and female,
> allowing for in-line insertion between a transmitter or RF amplifier  
> and
> load.  The 410 - series meter AC probe is used with the coupler by
> unscrewing the probe tip and then carefully inserting the probe into  
> the
> special "socket" on the coupler.  Those of you who have the 410  
> meters and
> AC probe will note that there are a pair of small screw heads that  
> protrude
> from the side of the probe body.  Those screw heads are used as the
> grounding and locking mechanism for the probe when it is installed  
> in the
> coupler.  It is sort of like a giant BNC connector arrangement,  
> because the
> action to insert the probe is a push-twist-lock sequence.  The  
> coupler has
> a special capacitor installed on a section of air dielectric  
> transmisison
> line, and the probe contacts that capacitor when properly seated.
>
> I have a downloaded copy of the military manual for the 410 meters.   
> That
> manual also refers to a neat accessory that I have never seen:  it  
> is the
> Model 11043A Probe N Connector.  There is no photo of it, but from the
> description, I get the impression that this is a device that  
> connects to
> the end of the 410's AC probe (probably also by unthreading the  
> existign
> probe tip) and replaces the stiff wire tip with a Type N connector.   
> If
> anyone on the list has one of these or has ever seen one, please let  
> me
> know if my suppostion is correct.  No, I do not wish to purchase one.
> However, this may be a very useful item, so I included it with this
> posting.
>
> I did not know until a few years ago that another company made a
> specialized version of the 11042A coupler described above.  At a  
> hamfest, I
> found an RCA Type CP-T75N coupler, Part #1044899-50.  It is an exact
> duplicate in body of the H-P coupler, BUT with 2 important  
> differences:
>
> 1) It is for 75 ohm system use, and is equipped with Type N 75 ohm
> connectors (which are NOT inter-mateable with 50 ohm Type N)
>
> 2) It has a different value of special capacitor for the probe to  
> contact
> when inserted
>
> I suspect that this special probe was made for radar applications,  
> as it
> was made by RCA Canada, Limited.  It might have also been used in
> television systems, but I am not sure.  RCA did a lot of radar work  
> back
> several decades ago. ...
>

The HP archive site has a catalog that lists the 455a. You can get  
that catalog at:
<www.hparchive.com/Catalogs_Specialized/HP-Catalog-195x-UHF-Equipment.pdf 
 >
But as you found in other places, it does not tell much about the  
insides.

Roy

Roy Morgan
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Groton NY, 13073
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Cell: 301-928-7794