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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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7th Jan 2013, 8:25 am | #1 |
Retired Dormant Member
Join Date: Jan 2013
Location: Bologna, Italy.
Posts: 2
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DORAM Distortion Meter circa 1975
Hi everybody,
A fellow of mine has found this instrumen. Used to work, it was used to test distortion while designing audio power amp, manufactured circa 1975. No other info. Looking for information about it, how to use it, possibly a manual. Thanks a lot. Alessandro |
7th Jan 2013, 11:01 am | #2 |
Pentode
Join Date: Oct 2011
Location: Oldham, Greater Manchester, UK.
Posts: 167
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Re: DORAM Distortion Meter circa 1975
A quick google found
http://www.epemag.wimborne.co.uk/history2.htm It appears DORAM was part of RS "DORAM Ltd. (the Doorway to Amateur Electronics) traded as the amateur's offshoot of RS Components Ltd, but was later closed down. RS later launched Electromail instead, based on the RS catalogue." Perhaps RS may have some record of your distortion meter? Frank C. |
7th Jan 2013, 11:01 am | #3 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,803
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Re: DORAM Distortion Meter circa 1975
Doram was a company in Leeds selling electronic components to the public, and also selling a number of kits. I remember them seeming to have high prices.
They were owned by RS Components Ltd (previously called Radiospares Ltd) At that time RS were the most comprehensive catalogue firm for components. Their stuff was expensive (and still is) but they are notorious for only dealing with trade account holders. By the time their components were marked-up for retail sale, they were definitely overpriced. Doram didn't seem to last for long. Leeds was and is also the home base for RS's greatest rival, Farnell. Farnell were usually a bit cheaper and they were/are happy to sell to anyone. I'm surprised Doram lasted at all. Your photo is the first bit of Doram equipment I've seen in 30+ years. Good luck on the manual hunt! The people on this group have surprised me many times. David
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3rd Mar 2014, 11:35 am | #4 | |
Retired Dormant Member
Join Date: Mar 2014
Location: Brisbane Queensland Australia
Posts: 2
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Re: DORAM Distortion Meter circa 1975
Quote:
It runs sine and square wave outputs from around 9Hz through to 100 Khz up to 3 volts p-pk on sine and 10 v p-pk on squarewave. Upon opening the rear panel, I could tell is was a very nice early/mid 70's build with Radio-Spares quality 240 volt / 115 volt power transformer ( 3 VA in size ) and a thermistor stabilized Audio Oscillator; with a Power Supply and metering PCB. 3 boards in all. All parts were neatly laid out and well marked. The only thing missing on my unit was two of the small stick-on rubber feet - easy fix. I would appreciate anyone who might be able to assist with tech data, a schematic diagram, or service manual for the unit. My application is for testing Vacuum Tube audio gear. If anyone has the matching Audio Distortion Meter they want to part with, for me to match up, I would be most interested. Kimbal. Last edited by Station X; 3rd Mar 2014 at 12:41 pm. Reason: Email address removed. |
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4th Mar 2014, 2:31 am | #5 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,803
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Re: DORAM Distortion Meter circa 1975
They were badly overpriced and were selling into a market where people compared specs and prices quite carefully.
Your oscillator will work with any other make of distortion meter. You'll find them by Heathkit, Levell, Lyons, Ferrograph, Radford, Tektronix and HP. The Radford ones are rather sought after (and their low distortion oscillator) HP did several models including ones which would automatically follow your tone around with their notch. (HP 8903) David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |