[time-nuts] DIY Frequency extension for HP Agilent 53181A, 53131A or 53181A

Mon Feb 16 00:33:44 UTC 2009

About prescaler :

Well, that's not as simple as I first thought. First, I need a prescaler
able to ramp from 100 MHz to 3+ GHz. And all prescalers I saw come with
horrible sensitivity in the 0.1-0.4 GHz range. More, they are all obsoletes
and not produced anymore. 

Now, I understand the choice of Agilent to use a massive 4-stage amplifier
in order to feed the prescaler with a usable signal in the 0.1-0.4 GHz
range. 

So, there is two choices :

- Rebuild the exact replica of the original 3-GHz option. The amplifiers are
still produced by Avago and I can source 10- or 20- MB510-PF on a old-parts
broker. 

- Build an entirely new design with a 2-stage divider : First Hittite 13 GHz
/8 divider, then any 2 GHz divider. With some good shielding and a bit of
amp, it may work fine as a 13 GHz prescaler.

I think I will try the first option first, and, if all goes well, switching
to the 13 GHz part. Now, I need to source some MB510-PF and design a PCB.

I think I will sold the extension as a kit. I just can't solder all the SMD
for everybody, but the kit will include all the components, including the
passives components and will be sold at a VERY reasonable price.  

-----Message d'origine-----
De : time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] De la
part de Samuel D. [x86/CPC]
Envoyé : dimanche 15 février 2009 22:05
À : 'Discussion of precise time and frequency measurement'
Objet : Re: [time-nuts] DIY Frequency extension for HP Agilent 53181A,
53131A or 53181A

You're right.

On the J2 connector, there is :

* Frequency output : Where the divided input frequency goes.
 - Pin 2 on counter - Pin 6 on EXT_PCB

* CH3CODE0 & CH3CODE1 : Used to detect the type of prescaler 
 - Pin 9&10 on counter - Pin 5&10 on EXT_PCB
 - 1/1 on 12.4 GHz board - 0/0 on 3 GHz board - 0 = GND / 1 = +5V

* CH3_DET_EN : Presence detection. Active low.
 - Pin 4 on counter - Pin 7 on EXT_PCB
 - If grounded, CH3 is enabled

* 5V line 
 - Pin 7 on counter - Pin 4 on EXT_PCB

* 12V line 
 - Pin 5&6 on counter - Pin 3&8 on EXT_PCB

* Ground 
 - Pin 1&3 on counter - Pin 1&2 on EXT_PCB

The 3 GHz board is built with 4-stage of Avago MSA-0986 (7 dB gain each,
rated 0.1 to 3 Ghz) and a fujitsu MB510-PF divider, rated up to 2.7 GHz. Pin
6 & 3 of the MB510-PF are high, so the divide ratio is set to 128.

Reproduce this will not be a problem. MSA-0986 costs $4.2 each and MB510-PF
is sold for no more than $7. Keep in mind that Agilent sold the board for
$2000 !

BTW, I wasn't able to determinate the divider ratio of the 12.4 GHz board :
U1 is not on the schematics and U2 is only a 2 GHz divider ML12034-5P from
Lansdale Semi (set to /64).

I think I will focus on the 3 GHz ext board first.

-----Message d'origine-----
De : time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] De la
part de RFSPACE
Envoyé : dimanche 15 février 2009 21:09
À : richard at karlquist.com; Discussion of precise time and frequency
measurement; mccorkle at ptialaska.net
Objet : Re: [time-nuts] DIY Frequency extension for HP Agilent 53181A,
53131A or 53181A

Samuel,

The prescaler option is detected by pin 9 and 10 of the 10 pin header. If 
you look at the page3 of 4 of the 53132A, you see a pair of pins called 
CH3CODE1 and CH3CODE0. Those tell the processor that the board is plugged 
in. If you go to the page for the 12.4 GHz prescaler, you can see that the 
pins 5 and 10 can be pulled high or low to tell the counter what board it 
is. The pinout on the main board and the prescaler board is different to 
confuse the hacker. The pinout on the prescaler board is:

6-1
7-2
8-3
9-4
10-5

the pinout on the main board is:

2-1
4-3
6-5
8-7
10-9

This is why the pins 10 and 5 that are used to ID the board, match the 
schematic pins 9 and 10. It looks really simple to build this board. I would

like to add 3GHz to my HP53131A. Currently I use a programmable divider from

Hittite. I have it set to /10 and do the math in my head.

Pieter, N4IP

----- Original Message ----- 
From: "Rick Karlquist" <richard at karlquist.com>
To: <mccorkle at ptialaska.net>; "Discussion of precise time and frequency 
measurement" <time-nuts at febo.com>
Sent: Sunday, February 15, 2009 2:53 PM
Subject: Re: [time-nuts] DIY Frequency extension for HP Agilent 53181A, 
53131A or 53181A

> Richard H McCorkle wrote:
>> Hi Samuel,
>>
>> I suggest starting by downloading the component level information for
>> the 53131A and 53132A from tha Agilent site at the following links.
>>
>> http://cp.literature.agilent.com/litweb/pdf/5989-6308EN.pdf
>> http://cp.literature.agilent.com/litweb/pdf/5989-6307EN.pdf
>>
>> The 53132A document includes a schematic of the channel C board with
>> parts list and may assist in getting you started.
>
> I see that they have a factory select resistor that unbalances
> the input slightly to keep the prescaler from oscillating with
> no input.  This a simple, obvious "solution" to this problem.
> It is also non-optimum, for three reasons.  It desensitizes the
> prescaler, it uses a factory select part that may not work
> consistently over temperature, and it still results in a range
> of input power where the counter displays garbage.
>
> In the 5334B C channel, I used a diode detector that turned on
> the counter at a repeatable input power.  Thus you never got garbage
> on the display due to low input power.  The detector used the
> well known circuit where you bias the diode on with a few 100
> microamps of DC and have a compensating diode that is not excited
> by RF.  A difference amp subtracts the compensating diode voltage.
> Simple, but effective.
>
> It is also interesting to note that in 1987 I used the MB506 prescaler.
> Here they have simply upgraded to the MB510.  Not likely to be
> any better on noisy sources.
>
> Rick Karlquist N6RK
>
>
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