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Products => Test Equipment => Topic started by: valvedoctor on August 28, 2013, 03:53:39 pm

Title: HP 5245L Counter: Reading 20% too high
Post by: valvedoctor on August 28, 2013, 03:53:39 pm

Hi everyone,

I recently got this counter on eBay for little over 100 bucks CND with shipping. Since I'm a tube nerd, I just couldn't pass on the nixie tube display. Everything seems to work correctly, but the reading are about 20% too high.  :palm:

Note, that I'm a tube guy and strictly analog in all my work, so I may need some assistance from fellow members on calibrating this unit.

Any suggestions?

Title: Re: HP 5245L Counter: Reading 20% too high
Post by: alm on August 28, 2013, 04:23:09 pm

20% high doesn't sound like a calibration issue to me. I'm not familiar with this instrument, but I would start by checking the voltage rails for both level and ripple. You will probably be able to find a scan of the service manual if it didn't come with one on either the Agilent website (http://www.agilent.com), the BAMA (http://bama.edebris.com/manuals/) and KO4BB (http://www.ko4bb.com/manuals/) manual sites or from commercial sellers Artek Manuals (http://www.artekmanuals.com) and Qservice (http://www.qservice.tv).

Title: Re: HP 5245L Counter: Reading 20% too high
Post by: Rufus on August 28, 2013, 05:31:08 pm

Quote from: valvedoctor on August 28, 2013, 03:53:39 pm

I recently got this counter on eBay for little over 100 bucks CND with shipping. Since I'm a tube nerd, I just couldn't pass on the nixie tube display. Everything seems to work correctly, but the reading are about 20% too high.

KO4BB has a service manual.

A stable signal generator would be helpful to diagnose. If it is 25% high one of the decade counters might be dividing by 8 instead of 10. In that case one of the digits won't go above 7.

Title: Re: HP 5245L Counter: Reading 20% too high
Post by: Clint on August 28, 2013, 05:41:20 pm

What a lovely piece of kit !!!!  :clap:

Title: Re: HP 5245L Counter: Reading 20% too high
Post by: valvedoctor on August 28, 2013, 06:47:41 pm

Thanks for replies. I do have the pdf manual from the site you provided.

As for a stable signal generator, I have an HP 456A sine generator up to 50mHz which is bang on. I also have a HP 5315A frequency counter, also bang on. As you can tell, I like my HP gear! :P

I haven't bothered to check the rear signal port on the back, directly from the crystal oscillator, but will do so and let you know.

I will check it out, and also I will sweep some frequencies to make sure all numbers are appearing on the decades.

Thanks again.