[time-nuts] Fixing an HP 5370A with a missing ROM board

Didier Juges time-nuts at ko4bb.com
Sun Jul 26 22:20:08 UTC 2009


One of my 5370A's does not have the reference oscillator. However, since I
use it with an external reference, it has not been a problem.

I understand that for some measurements (particularly if those measurements
involve that same external reference in some way), it would be better to use
an asynchronous internal source, but my needs have not been that elaborate
yet...

Didier 

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Mark Sims
> Sent: Friday, July 24, 2009 4:33 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] Fixing an HP 5370A with a missing ROM board
> 
> 
> For some strange reason,  5370A's with missing ROM boards 
> seem to be more common than one would expect.  I now know 
> there are at least two others...
> 
> Another question to ask is how many 5370's are out there 
> without the oven oscillator option?  It  might be worthwhile 
> doing a small run of oven oscillator power supply boards.  
> I also noticed that the 5370 drives the oven with unregulated 
> power.  I suspect one could get better performance by using a 
> regulated power supply.  The 10811 spec is 2.5e-10 for a 10% 
> change in oven voltage so the improvement would not be a 
> whole bunch,  but is noticeable.  I did a test with a variac 
> and could see the effect over what my normal line voltage 
> daily range is.  The oven power is generated via a bridge 
> rectifier / 16V transformer winding which generates a nominal 
> 22V,  not much headroom to meet the 20V oscillator spec,  but 
> doable...  I see another pimp 'yo 5370 project coming.
> 
> ----------------------------------------
> While I don't have a need for your mod...
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