Re: [time-nuts] Trimble 65256 OCXO

[Dave Brown]

Thanks for confirming my suspicions, Bob. I'm using a 10k 10 turn pot across 
the regulated 12v supply at present to feed the EFC but I'll change to using 
pin 5.

DaveB, NZ


- Original Message - 
From: "Bob Camp" <kb...@n1k.org>
To: "Discussion of precise time and frequency measurement" 
<time-nuts@febo.com>

Sent: Monday, November 28, 2016 3:17 AM
Subject: Re: [time-nuts] Trimble 65256 OCXO



Hi

Pin 5 is the EFC reference pin. It may (or may not) have a voltage on it. 
If there is a
voltage on it, it’s a voltage that the original OEM customer found useful. 
It may (or may not)

have a series resistor to match up with an OEM specified trim pot.

Bob


On Nov 27, 2016, at 2:04 AM, Dave Brown <tract...@ihug.co.nz> wrote:

This 10 MHz unit has a 5th pin that I can't find any documentation about. 
There have been posts in the past that have also indicated its use is 
unknown.  Looking at the base, the four connections in the corners are 
known quantities. (ground, EFC, 10 MHz out and + supply) No. 5 is midway 
along one side.
I thought it may be a reference supply for the EFC pin- with a 12.03 volt 
supply the unknown pin measures at 2.803 volts-which is usefully above 
the required EFC voltage ( ~2.4 volts) to bring it on frequency.

But does anyone have some hard data on this 'unknown' pin?
DaveB, NZ


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Re: [time-nuts] Trimble 65256 OCXO

[Bob Camp]

Hi

Pin 5 is the EFC reference pin. It may (or may not) have a voltage on it. If 
there is a 
voltage on it, it’s a voltage that the original OEM customer found useful. It 
may (or may not)
have a series resistor to match up with an OEM specified trim pot.

Bob

> On Nov 27, 2016, at 2:04 AM, Dave Brown  wrote:
> 
> This 10 MHz unit has a 5th pin that I can't find any documentation about. 
> There have been posts in the past that have also indicated its use is 
> unknown.  Looking at the base, the four connections in the corners are known 
> quantities. (ground, EFC, 10 MHz out and + supply) No. 5 is midway along one 
> side.
> I thought it may be a reference supply for the EFC pin- with a 12.03 volt 
> supply the unknown pin measures at 2.803 volts-which is usefully above the 
> required EFC voltage ( ~2.4 volts) to bring it on frequency.
> But does anyone have some hard data on this 'unknown' pin?
> DaveB, NZ
> 
> 
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Re: [time-nuts] Trimble 65256 OCXO

[Hal Murray]

tract...@ihug.co.nz said:
>  I thought it may be a reference supply for the EFC pin- with a 12.03 volt
> supply the unknown pin measures at 2.803 volts-which is usefully above the
> required EFC voltage ( ~2.4 volts) to bring it on frequency.
>  But does anyone have some hard data on this 'unknown' pin? 

Is it input or output?  What happens if you pull it to ground with a 10K or 
1K resistor?  Or measure the impedance when powered off.

2.8 volts seems a bit low to be a useful supply.


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[time-nuts] Trimble 65256 OCXO

[Dave Brown]

This 10 MHz unit has a 5th pin that I can't find any documentation about. 
There have been posts in the past that have also indicated its use is 
unknown.  Looking at the base, the four connections in the corners are known 
quantities. (ground, EFC, 10 MHz out and + supply) No. 5 is midway along one 
side.
I thought it may be a reference supply for the EFC pin- with a 12.03 volt 
supply the unknown pin measures at 2.803 volts-which is usefully above the 
required EFC voltage ( ~2.4 volts) to bring it on frequency.

But does anyone have some hard data on this 'unknown' pin?
DaveB, NZ



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Re: [time-nuts] Trimble 65256 OCXO info?

[Frister]

Bob,
I've used one for a simple 10 Mhz ref.
They are 12 V, and indeed the VFC is +2.5V
If you hold the OCXO upside down, the 2 pins at the top are GND and +12V
Bottom 3 Pins - 10 Mhz, unknown and VFC

Frits W1FVB

On 09/06/2015, Bob Stewart b...@evoria.net wrote:
 Does anyone have any information about the Trimble 65256 OCXO?  I bought one
 recently and hooked it up to 12V per the vendor.  (Yeah, I know.)  Although
 it worked, it set off such a stench: the usual electronics burning up, give
 you a sore throat smell.  So, I got a replacement and same thing.  For fun,
 I hooked it up to +5V.  It seems to work, it drives the counter, but I
 haven't measured the output waveform yet.  So, does anyone know whether
 these are +12V devices, +5V, or something else?  The VRef output was
 somewhere around +2.5V, IIRC.

 Bob - AE6RV

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[time-nuts] Trimble 65256 OCXO info?

[Bob Stewart]

Does anyone have any information about the Trimble 65256 OCXO?  I bought one 
recently and hooked it up to 12V per the vendor.  (Yeah, I know.)  Although it 
worked, it set off such a stench: the usual electronics burning up, give you a 
sore throat smell.  So, I got a replacement and same thing.  For fun, I hooked 
it up to +5V.  It seems to work, it drives the counter, but I haven't measured 
the output waveform yet.  So, does anyone know whether these are +12V devices, 
+5V, or something else?  The VRef output was somewhere around +2.5V, IIRC.

Bob - AE6RV

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