EEVblog Electronics Community Forum

Products => Test Equipment => Topic started by: AwArD_RzD on July 28, 2014, 01:31:18 am

Title: Used signal generator parts life span
Post by: AwArD_RzD on July 28, 2014, 01:31:18 am

In the next few month i will need a good signal generator, i saw many post in different forum where ppl was buying old discontinued Agilent ESG serie and they all had good review of this series, i started to check for the E4421B model and many seller posted the diagnostic menu where you can see the power cycle, power on and the attenuator cycle.

I saw many unit with over 40k hour power on with very low attenuator cycle (in the range of 1000 to 3000) and many other unit with 15k-25k hour power on but with some 2 000 000 - 3 000 000 attenuator cycle, all around the same price. I understand the million cycle indicate these unit was on a test bench and can switch off an on the attenuator 2-3 time per minute (124 time/hour for one unit in example), but do i need to worry about this electronic part and the high cycle count ?? (the attenuator is not mechanical in these unit) 

Title: Re: Used signal generator parts life span
Post by: KJDS on July 28, 2014, 06:53:48 am

I've not looked inside one in over a year, but I thought it was a mechanical attenuatorB.

If it isn't then it isn't important. If it is then I'd be concerned about several million switching operations.

Title: Re: Used signal generator parts life span
Post by: nctnico on July 28, 2014, 07:13:25 am

My E4421B (still in restauration) has an electronic attenuator which doesn't wear out. The service manual could shine a light on which serial numbers have an electronic attenuator.
If you get one of these generators be sure to put thermal paste under the end amplifier otherwise it may overheat.

Title: Re: Used signal generator parts life span
Post by: cyr on July 28, 2014, 09:20:19 am

My E4421B has 58k hours and 12.6M attenuator cycles on it, works perfectly.
Only option UNB (higher output power) uses a mechanical attenuator.

Title: Re: Used signal generator parts life span
Post by: AwArD_RzD on July 28, 2014, 01:06:32 pm

Thanks for the reply,

@nctnico
Where is this end amplifier located ?

I tried to find the Service documentation, assembly and component manual but it's only available at purchase and it's 370$ CAN, anyone have it in PDF format ??

Title: Re: Used signal generator parts life span
Post by: nctnico on July 28, 2014, 11:52:10 pm

The service manual can be downloaded from HP. Don't expect schematics but the end amplifier can't be missed on the output board.

Title: Re: Used signal generator parts life span
Post by: AwArD_RzD on July 29, 2014, 01:21:33 am

Quote from: nctnico on July 28, 2014, 11:52:10 pm

The service manual can be downloaded from HP. Don't expect schematics but the end amplifier can't be missed on the output board.

don't know why i missed it, it's the third link on google d'oh!! Thanks !