[time-nuts] Questions about HP 5370B

[Paramithiotti, Luciano Paolo S]

***It does sound like the 10811's oven fuse is open, though.  (The counter won't work if there's no oscillator present at all.)***

R: oven's fuse is on +24vdc for the power part of the oven. The oscillator work with +12 volts that is not fused. So, some time happen the oscillator work but the oven not at all. 

Luciano
Luciano P. S. Paramithiotti
IZ5JHJ


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of John Miles
Sent: martedì 14 settembre 2010 10.23
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Questions about HP 5370B


> Yes, the rear heatsink does run very hot, approx. 61 deg C. But do 
> make sure the fan is running! The unit will be damaged without the 
> fan. Also it's important to refrain from running the instrument too 
> long with its top cover removed, because the fan air doesn't properly 
> loop around and blow back out the heatsink if you've left the 
> instrument top cover off.

There are no such concerns with the 5370B as far as I'm aware.  Nothing in there runs very hot except the linear regulators themselves, which are externally heatsinked.

It does sound like the 10811's oven fuse is open, though.  (The counter won't work if there's no oscillator present at all.)
> As Bruce suggests, you'll want to peek inside to see that you really 
> do have a 10811 oscillator. If so, then it sounds like the thermal 
> fuse (F1, inside the 10811) might be open. According to the manual, I 
> think the HP part number for F1 was 2110-0617. However, Agilent's 
> current online parts search does not find that p/n. Maybe you'll have 
> to call Agilent's "Parts ID" to identify the current part number for 
> F1?  ...Or probably others in this forum will offer more current 
> information regarding what part to

Just short it out, or if you like, put in an NTE part with a similar temp rating.  It serves little or no useful purpose.

-- john, KE5FX


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