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Article #21179Re: Who has dummy speaker loads?
From: Robert Wier
Date: Tue, 18 Apr 1989 22:25
Date: Tue, 18 Apr 1989 22:25
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1736 bytes
Regarding audio dummy loads... I once used (many years ago) a light bulb to tune up my amateur radio transmitter. Kind of neat to see the light flash in synch with your voice on SSB. However, it's not recommended because 1) the load is complex (lots of inductance), 2) the resistance of the filament changes as it heats up and cools down and 3) it radiates (leaks) rf. I once made a 500+ mile contact on a 50 watt light bulb (ahem...) Heathkit sells a "Cantenna" which is basically a one gallon paint can with a 50ohm resistor suspended inside. The idea is that you fill it with mineral or transformer oil which will circulate and dissapate any heat. Its rated up to 1,000 watts up to a frequency of 450 Mhz. I would suppose you'd want something in the range of 4-12 ohms for audio work. I note that in the Newark catalog they have Dale high wattage resistors. You could parallel, say, 5 20W 100 ohm values and come out with something usable. If you stick 'em into a cantenna, the rating would be considerable higher... - Bob Wier College of Engineering Flagstaff, Arizona Northern Arizona University ...arizona!naucse!rrw | BITNET: WIER@NAUVAX | *usual disclaimers*
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Path: arc1-ca.pugleaf.net!utzoo!dptcdc!jarvis.csri.toronto.edu!mailrus!ames!ncar!noao!arizona!naucse!rrw From: rrw@naucse.UUCP (Robert Wier) Newsgroups: sci.electronics,rec.audio Subject: Re: Who has dummy speaker loads? Keywords: dummy, speaker, load, watt Message-ID: <1352@naucse.UUCP> Date: 18 Apr 89 22:25:45 GMT References: <3474@nunki.usc.edu> <382@sagpd1.UUCP> Distribution: na Organization: Northern Arizona University, Flagstaff, AZ Lines: 27