Author Topic: just bought HP 8657A from Ebay, how to test it ?  (Read 5363 times)

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Offline danny_isrTopic starter

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just bought HP 8657A from Ebay, how to test it ?
« on: May 15, 2016, 05:22:50 pm »
The EBay seller gave me 30 days to check it  :-+
I'm not an RF guy (just getting to it). I did just basic stuff with it so far.
Seems the output signal in the frequencies i tried is ok on my scope and analyzer, played with the AM and FM modulations.
But i know i barely scratch the surface. Are there any "known" issues i should look for ?
or interesting "stress test" i should try ?

Another thing i noticed. When it's OFF. I can hear a ham. Probably from the supply. Is that normal ?
it's REALLY low, i had to be in a complete silent room to hear this.
« Last Edit: May 15, 2016, 05:30:41 pm by danny_isr »
 

Offline linux-works

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Re: just bought 8657A from Ebay, how to test it ?
« Reply #1 on: May 15, 2016, 05:30:50 pm »
Quote
When it's OFF. I can hear a ham coming out of it.

is he sending CW or SSB?

its not glazed, though, is it?

(sorry) ;)

Offline danny_isrTopic starter

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Re: just bought HP 8657A from Ebay, how to test it ?
« Reply #2 on: May 15, 2016, 05:32:53 pm »
haha i was asking for it  :-DD
Hum not ham  |O
 

Offline AF6LJ

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Re: just bought HP 8657A from Ebay, how to test it ?
« Reply #3 on: May 15, 2016, 07:12:15 pm »
Very nice find.
Sue AF6LJ
 

Offline veedub565

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Re: just bought HP 8657A from Ebay, how to test it ?
« Reply #4 on: May 15, 2016, 07:27:49 pm »
To check it out you need section 4 "Performance Verification" in the service manual

http://literature.cdn.keysight.com/litweb/pdf/08657-91039.pdf?id=723528
 

Offline G0HZU

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Re: just bought HP 8657A from Ebay, how to test it ?
« Reply #5 on: May 15, 2016, 08:10:07 pm »
Note that 219mV (pd) is approx 0dBm so if this is 219mV pd (rather than emf) I'd expect to see close to 0dBm on the analyser assuming you are using a decent quality RF cable to connect to the Rigol. But your plot shows a much lower level.

In terms of initial quick and dirty checks I would check the output attenuator to see if it steps correctly right down to tiny signal levels using your Rigol spectrum analyser on a narrow span. . eg check every major step of the attenuator right down to something like -120dBm on the analyser. It should give a click or clonk each time the attenuator makes a major step change. If the attenuator is faulty you will see holes or strange level changes as you wind down the output level from 0dBm to -120dBm using the up/down key buttons in 1dB steps.

Also, make sure it gives the correct output on the two main frequency sub ranges on the block diagram in terms of frequency lock.

This probably means testing it across the range 100kHz through to 130MHz (in 10MHz steps?) and also from 130MHz up to 1000MHz in 10MHz steps to make sure it stays in lock on every step.

Also, check that every front panel button 'works' and isn't intermittent or deaf. Sometimes these can wear out although I don't know if the 8657A is prone to this or not.

Also, it probably self tests all the display segments on bootup. If so, are there any dead segments in the display?

But ideally, you would need to check it as per the manual asveedub565 states :)

I've never used the HP8657A as this is not one of HP's finest sig gens. The A versions have poor close in phase noise and feature quite a few spurious terms. However, as long as you don't expect to use it for semi serious testing of (for example) an HF radio or some other system that demands low spurious and phase noise then it will be fine for general use.



« Last Edit: May 15, 2016, 08:30:18 pm by G0HZU »
 

Offline danny_isrTopic starter

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Re: just bought HP 8657A from Ebay, how to test it ?
« Reply #6 on: May 15, 2016, 09:11:31 pm »
Note that 219mV (pd) is approx 0dBm so if this is 219mV pd (rather than emf) I'd expect to see close to 0dBm on the analyser assuming you are using a decent quality RF cable to connect to the Rigol. But your plot shows a much lower level.


i have a 30db attenuator on the spectrum input
 

Offline EV

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Re: just bought HP 8657A from Ebay, how to test it ?
« Reply #7 on: May 16, 2016, 06:44:45 am »
Another thing i noticed. When it's OFF. I can hear a ham. Probably from the supply. Is that normal ?
it's REALLY low, i had to be in a complete silent room to hear this.

I have HP8642A and there is always power on to keep data in memory. If power cord is taken off the memory will be empty quite soon. The battery is capacitor type if I remember right. Maybe it is same thing with your generator. You can look from manual to be sure.
 

Offline rf-loop

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Re: just bought HP 8657A from Ebay, how to test it ?
« Reply #8 on: May 16, 2016, 08:29:44 am »
These HP generators have also Optional better accuracy freq reference. (if there is optional reference it need connect in back side using short coax.  Front panel power on/off is not total power on/off. These are On/Stby. In Stby state it still keep possible optional (OCXO) reference Owen powered.
If I remember right both, HP8657A and 8657B,  have Li Battery inside for keep last state (if selected to keep) and 100 user settings memory what also can use for running sequences.
(there is not (just in these models) any kind of important cal or other system data in RAM. Just user memory)
EV of course. Cars with smoke exhaust pipes - go to museum. In Finland quite all electric power is made using nuclear, wind, solar and water.

Wises must compel the mad barbarians to stop their crimes against humanity. Where have the (strong)wises gone?
 


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