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 Post subject: Heathkit frequency counters
PostPosted: Jun Mon 23, 2003 12:42 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2846
Location: Warwick,RI
Anybody got any comments to make regarding any of the Heath counters before I look for one to possibly bid on?Anything I need to watch out for?What about replacement crystals;are they readily available and do they commonly go bad?<BR>Thanks,<BR>Malcolm<P>------------------<BR>


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 Post subject: Heathkit frequency counters
PostPosted: Jun Tue 24, 2003 12:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4003
Location: Malone, New York USA
<BR> I have a Heathkit model IM-2410.<BR> Always tandemed to whichever sig. gen in use.<BR> Certainly not lab quality, but it hasn't "lied" to me yet.<BR> Great for my old radio purposes. <P> 10 hz-225 mhz in two ranges<BR> .1 or 1 second sampling rates<BR> <BR> Large LED readout.<BR> <BR> I like it.<P> Den<P>------------------<BR>


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 Post subject: Heathkit frequency counters
PostPosted: Jun Wed 25, 2003 4:06 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3550
Location: Harviell MO USA 63945 (12 miles S of Poplar Bluff)
Malcolm, crystals go bad about as often as Billy Graham, so no worries there. A lot of counters have an external timebase input (or you could wire in a simple switching circuit to add an external input) so that you could bypass the less-accurate internal timebase with a more-accurate oscillator if you ever got your hands on one. Most crystal oscillators used in inexpensive (i.e., non-lab-grade) counters are good to 0.001% and sometimes as good as 0.0001%. Surprisingly, a TCXO (temperature-compensated crystal oscillator) doesn't improve accuracy all that much, usually by a factor of 4 or 5. But overall, this means that the display of a lot of counters will outperform the timebase in that the last few digits of the display aren't really valid for quantative measurements, although they'll be OK for short-term checks on drifting of the input signal. For work on antique radios? The lousiest counter will be more accurate than any of the kit signal generators!<P>Dean<BR><P>------------------<BR>


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 Post subject: Heathkit frequency counters
PostPosted: Jun Wed 25, 2003 8:12 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 974
I have a Heathkit IM-4120 counter and an HP 3325A 20 MHz synthesizer, both of which run on their internal standards. If I set the generator to 20.0000000 MHz, 100 mV or more p-p, the counter will agree within 20 Hz at turn-on, and within 20 Hz in the other direction after an hour. <P>I think the counter is from the late '70s. I bought it used, cheap, and seem to remember resoldering a display connection about 15 years ago, but it has been otherwise trouble free. The HP was free because it was deemed BER where I used to work, due to an intermittent problem that on my watch has been no more visible than Iraqi WMDs have been during the Bush Administration--though I do have more credible evidence of its existence.<P>------------------<P>


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 Post subject: Heathkit frequency counters
PostPosted: Jun Thu 26, 2003 2:04 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2846
Location: Warwick,RI
Thanks to both of you for the info.I had intended to use a counter to check the accuracy(or lack of same) on vintage generators.It appears that even a lower priced counter,that has been kicking around for years is a miracle of accuracy compared to a service grade 60's era tube signal generator,so I guess choice is not critical at all for my needs.<BR>Malcilm<P>------------------<BR>


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