just bought HP 8657A from Ebay, how to test it ? - Page 1
Forum section: electronics / testgear

author: danny_isr
author_rank: Regular Contributor
timestamp: May 15, 2016, 05:22:50 pm
content: The EBay seller gave me 30 days to check itI'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.

author: linux-works
author_rank: Super Contributor
timestamp: May 15, 2016, 05:30:50 pm
content: Quoteis he sending CW or SSB?its not glazed, though, is it?(sorry)

author: danny_isr
author_rank: Regular Contributor
timestamp: May 15, 2016, 05:32:53 pm
content: haha i was asking for itHum not ham

author: AF6LJ
author_rank: Unknown
timestamp: May 15, 2016, 07:12:15 pm
content: Very nice find.

author: veedub565
author_rank: Frequent Contributor
timestamp: May 15, 2016, 07:27:49 pm
content: To check it out you need section 4 "Performance Verification" in the service manualhttp://literature.cdn.keysight.com/litweb/pdf/08657-91039.pdf?id=723528

author: G0HZU
author_rank: Super Contributor
timestamp: May 15, 2016, 08:10:07 pm
content: 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 statesI'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.

author: danny_isr
author_rank: Regular Contributor
timestamp: May 15, 2016, 09:11:31 pm
content: Quote from: G0HZU on May 15, 2016, 08:10:07 pmi have a 30db attenuator on the spectrum input

author: EV
author_rank: Frequent Contributor
timestamp: May 16, 2016, 06:44:45 am
content: Quote from: danny_isr on May 15, 2016, 05:22:50 pmI 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.

author: rf-loop
author_rank: Super Contributor
timestamp: May 16, 2016, 08:29:44 am
content: 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)