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From: k1ggi <k1ggi@...>
Sent: Nov 20, 2007 7:43 PM
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] Re: 8640B External Reference

The 8640B external reference can be configured to accept a 1MHz input,
but the jumpers are deeply buried in the time-base module on A8A3.

It is not necessary for the reference to be a sinusoid. It is first
attenuated and then amplified before being fed into a logic gate,
which feeds the counter chain.

The internal oscillator always runs and there can be some weak
crosstalk that beats the internal with the external reference, which
can show up when they are very close in frequency as very close-in
spurs.

73, Ed, K1GGI

--- In hp_agilent_equipment@..., "Richard W. Solomon"
<w1ksz@...> wrote:

So basically what you are telling me is that it is not worth the

effort to try and supply

an external reference to the 8640B, yes ??
I have two TrueTime XL-AK GPS Receivers that have 5 outputs on the

rear, internally selectable

for 10, 1, .1, .01 MHz and 1 pps outputs. I guess I'll just use one

to supply the counters.

Thanks for the replies.

73, Dick, W1KSZ/7

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From: arthurok <arthurok@...>
Sent: Nov 20, 2007 7:01 PM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] 8640B External Reference

a flip flop and simple low pass if needed is too much for an extra class ham to build up??
----- Original Message -----
From: Richard W. Solomon
To: hp_agilent_equipment@...
Sent: Tuesday, November 20, 2007 7:56 PM
Subject: Re: [hp_agilent_equipment] 8640B External Reference


So basically what you are telling me is that it is not worth the effort to try and supply
an external reference to the 8640B, yes ??
I have two TrueTime XL-AK GPS Receivers that have 5 outputs on the rear, internally selectable
for 10, 1, .1, .01 MHz and 1 pps outputs. I guess I'll just use one to supply the counters.

Thanks for the replies.

73, Dick, W1KSZ/7

-----Original Message-----
>From: lothar baier <microwaveengineer1968@...>
>Sent: Nov 20, 2007 5:08 PM
>To: hp_agilent_equipment@...
>Subject: Re: [hp_agilent_equipment] 8640B External Reference
>
>One thing need to be made clear however, the external timebase will not affect the frequency stability in normal operating mode since it is only used for the frequency counter, if you push the phaselock button then it will lead to an increased stability of the signal.
> Another possibility is to get a 5078A distribution amplifier which would be usefull since he wants to drive some other counters and stuff as well, as far as i know HP made cards to go in those that allowed for a 5MHz or 1MHz output, anyway a 2/1 divider is easy enough to build, you can use TTL or just go to hittite and buy a part for about $2, lowpass filters are wasy to build or you can get a little monolithic one from coilcraft or mini circuits
>
>
> as he says a low pass filter will produce a quasi sine wave "gaussian responce"
>----- Original Message -----
>From: lothar baier
>To: hp_agilent_equipment@...
>Sent: Tuesday, November 20, 2007 5:58 PM
>Subject: RE: [hp_agilent_equipment] 8640B External Reference
>
>sorry i wasnt to clear on that, the DDS i was refering to actually has a clock multiplier build in that allow a max of 30MHz i think.
>
>Mike Feher <n4fs@...> wrote: If you use 10 MHz as a clock for a DDS, then, you are just as well off using
>a flip-flop. Your output will be just a 5 MHz square wave either way. Now if
>you were to multiply the 10 MHz up first, like even just doubling it to 20
>MHz, then you will have easily exceeded Nyquist and you also have room to
>put in a nice filter for 5 MHz. Still, the best recommendation was the first
>one. Just divide by two and filter. You may not even need to filter as most
>counters use a square wave anyway. 73 - Mike
>
>Mike B. Feher, N4FS
>
>89 Arnold Blvd.
>
>Howell, NJ, 07731
>
>732-886-5960
>
>_____
>
>From: hp_agilent_equipment@...
>[mailto:hp_agilent_equipment@...] On Behalf Of lothar baier
>Sent: Tuesday, November 20, 2007 5:37 PM
>To: hp_agilent_equipment@...
>Subject: Re: [hp_agilent_equipment] 8640B External Reference
>
>5MHz was quite common back then, it had to do with the fact that 5MHz XO had
>a better phasenoise, you will also find 5MHz on many older rubidium and
>cesium beam standarts.
>You have basically two options, the first one is to just use a 2/1 frequency
>divider, you can find those at any semiconductor company fairly cheap, the
>other solution which is a bit more intricat is to use a DDS chip to generate
>your 5MHz out of a 10MHz XO
>
>"Richard W. Solomon" <w1ksz@earthlink. <mailto:w1ksz%40earthlink.net> net>
>wrote:
>After moving to Arizona I know have at least one of my GPS Stabilized
>Oscillators up and running. I intend to use the 10 MHz output as the
>External Reference for a couple of EIP Counters and I had hoped my
>8640B. But, HP in their infinite wisdom, has deemed that a 5 MHz
>reference is needed. Is there any way to change that from 5 MHz to 10
>MHz ? Maybe I should just stick 10 MHz in and see what happens ??
>
>Any thoughts on this ?
>
>Thanks, Dick, W1KSZ/7
>
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On Tue, 20 Nov 2007 23:28:02 -0000, you wrote:

They should at least be preserved, the Tek ones I remember went back
to the 50's and 60's and where 16MM.

I'd be willing to transfer them to DVD...

Harvey

From: lothar baier <microwaveengineer1968@...>
Sent: Nov 20, 2007 5:08 PM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] 8640B External Reference

One thing need to be made clear however, the external timebase will not affect the frequency stability in normal operating mode since it is only used for the frequency counter, if you push the phaselock button then it will lead to an increased stability of the signal.
Another possibility is to get a 5078A distribution amplifier which would be usefull since he wants to drive some other counters and stuff as well, as far as i know HP made cards to go in those that allowed for a 5MHz or 1MHz output, anyway a 2/1 divider is easy enough to build, you can use TTL or just go to hittite and buy a part for about $2, lowpass filters are wasy to build or you can get a little monolithic one from coilcraft or mini circuits


as he says a low pass filter will produce a quasi sine wave "gaussian responce"
----- Original Message -----
From: lothar baier
To: hp_agilent_equipment@...
Sent: Tuesday, November 20, 2007 5:58 PM
Subject: RE: [hp_agilent_equipment] 8640B External Reference

sorry i wasnt to clear on that, the DDS i was refering to actually has a clock multiplier build in that allow a max of 30MHz i think.

Mike Feher <n4fs@...> wrote: If you use 10 MHz as a clock for a DDS, then, you are just as well off using
a flip-flop. Your output will be just a 5 MHz square wave either way. Now if
you were to multiply the 10 MHz up first, like even just doubling it to 20
MHz, then you will have easily exceeded Nyquist and you also have room to
put in a nice filter for 5 MHz. Still, the best recommendation was the first
one. Just divide by two and filter. You may not even need to filter as most
counters use a square wave anyway. 73 - Mike

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell, NJ, 07731

732-886-5960

_____

From: hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...] On Behalf Of lothar baier
Sent: Tuesday, November 20, 2007 5:37 PM
To: hp_agilent_equipment@...
Subject: Re: [hp_agilent_equipment] 8640B External Reference

5MHz was quite common back then, it had to do with the fact that 5MHz XO had
a better phasenoise, you will also find 5MHz on many older rubidium and
cesium beam standarts.
You have basically two options, the first one is to just use a 2/1 frequency
divider, you can find those at any semiconductor company fairly cheap, the
other solution which is a bit more intricat is to use a DDS chip to generate
your 5MHz out of a 10MHz XO

"Richard W. Solomon" <w1ksz@earthlink. <mailto:w1ksz%40earthlink.net> net>
wrote:
After moving to Arizona I know have at least one of my GPS Stabilized
Oscillators up and running. I intend to use the 10 MHz output as the
External Reference for a couple of EIP Counters and I had hoped my
8640B. But, HP in their infinite wisdom, has deemed that a 5 MHz
reference is needed. Is there any way to change that from 5 MHz to 10
MHz ? Maybe I should just stick 10 MHz in and see what happens ??

Any thoughts on this ?

Thanks, Dick, W1KSZ/7

---------------------------------
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---------------------------------
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I acquired a box full of plug-ins for my 5245L counter and have a couple of
questions.

1. 5253B 50-500 MHz heterodyne oscillator The left most digit is not
displayed. i.e., 62.567 is displayed as 2.567. Is this the way it's
supposed to work?

2. 5257A Transfer Oscillator I can't find anything on the internet about
how to use it. I certainly don't want to spend any money on a manual until
I find out if it works and if it will be useful to me. Can some one give a
quick course in how to use it.

They should at least be preserved, the Tek ones I remember went back
to the 50's and 60's and where 16MM.

--- In hp_agilent_equipment@..., J Forster <jfor@...> wrote:

pdxoregonpete wrote:

The Tektronix movie masters were all trashed :(

About 10 years ago, I got a box of Tek VHS videos on NTSC video
measurements, etc. They might still be available, if wanted. Is it worth
checking?

-John

pdxoregonpete wrote:

The Tektronix movie masters were all trashed :(

About 10 years ago, I got a box of Tek VHS videos on NTSC video
measurements, etc. They might still be available, if wanted. Is it worth
checking?

-John