[FS] HP331A, HP334A, HP654A Signal Gen & Distortion Meters - Page 1
Forum section: electronics / general

author: TPI
author_rank: Contributor
timestamp: July 11, 2013, 06:30:53 am
content: I have three separate items I'd like to sell.They are:HP331A - RMS Voltmeter and Distortion AnalyserHP334A - RMS Voltmeter and Distortion AnalyserHP654A - 10Hz - 10Mhz Sine wave Signal GeneratorHP331AThis one is a little worse for wear, the banana plugs for the inputs and outputs have cracked. And a previous owner I believe has modified this unit to be able to accept a balanced audio input. Seen by the little extra switch under the power switch. The voltmeter on this over reads. It does come with a original service manual. The distortion meter function works fine as far as I can tell.HP334AThis unit is an improved version of the 331A, it has an automatic cancellation feature to aid in distortion measurement. The overall condition is much much better than the 331A. The voltmeter is close but still over reads just a little. And also the distortion meter functions correctly.HP654AThis is a 10Hz - 10Mhz Sine wave oscillator. It has selectable output impedances. The attenuation switch contacts are a little dirty and could do with a clean. The main frequency dial is a little scratched up. I found it to be very stable in both amplitude and frequency for its age. No manualPlease make me an offer on any of the three.They are located in South Melbourne for anybody in Victoria whom may want to try before they buy...They weigh about 7kg each - in case anybody was wondering about postage.

author: TerraHertz
author_rank: Super Contributor
timestamp: July 12, 2013, 01:57:01 am
content: Can you tell me - the two that have surface corrosion on the aluminium main control dials, are the gradations and numbers engraved in the dial and then paint filled, or just screened onto the surface of the dial?I'm asking because what you are selling is really a restoration project. I'm slightly interested (I like HP gear, though prefer units of a later generation), but those dials need resurfacing. And if the markings are not engraved, it wouldn't work. Sometimes HP dials like that are engraved, sometimes not.The case sides/handles also need to be taken off and resurfaced.Whoever ends up with them, I hope the three stay together.An example repair project:http://everist.org/tales/20130215_The_Q_meter.htm

author: TPI
author_rank: Contributor
timestamp: July 12, 2013, 04:14:18 am
content: The 331A has engravings and the 654A is printed on. The 334A is in perfect condition.Metal on the side handles also shows some signs of wear.

author: bboy_h
author_rank: Newbie
timestamp: July 12, 2013, 04:27:05 am
content: I would love the HP654A but have no idea what you would be expecting for it (or what I could afford as it would be for home/hobby use). Can you give me any more of an idea what your expecting?Feel free to PM me if desired.Thanks

author: vk6zgo
author_rank: Super Contributor
timestamp: July 12, 2013, 06:15:36 am
content: Both of the N&D sets accept balanced inputs ex-factory.The chromed link is used to unbalance the input.The switch on the HP331A seems to be to open circuit the input-------- seems like a strange mod!The auto-nulling on the HP334A is very Slo-o-w-w in operation,& my old employer took them out of service in areas where a lot of readings had to be taken in a hurry,& replaced by the AWA unit,which nulls very quickly.In a Lab environment,the slow nulling wouldn't matter,or you could just use manual nulling!