On Sun, 20 Sep 1998 14:35:50 -0400 km1h writes:
>
>On Sat, 19 Sep 98 18:40:59 -0800 Rich Measures <measures@vc.net>
>writes:
>
>>>Are you still harping on this subject Rich? I havent noticed any
>>>naysayers on the AMPs reflector since I reattached 5 weeks ago.
>>>
>>The article was not directed at any particular tribe. The IRE
>article
>>
>>was recently received by yours truly and I thought some folks might
>be
>>
>>interested. It would have been nice to have had the article during
>>the
>>grate parasite debate.
>>
>>>Reminds me of the horsecrap I got from a few "experts" about the use
>
>>of
>>>very slightly inductive 5W MOX resistors
>>
>>It wasn't equine feculence. I bought a few of those resistors and
>>they
>>were pretty inductive.
>So what? Where is it cast in stone that a small inductance as part of
>a 50-100 Ohm resistor is not going to work at HF or 6M? With a self
>resonance around 380MHz and no series resonances indicated explain why
>it would not work....which it does of course as proven by well over
>100 amplifiers using them.
>Take a look at the self resonance of typical Centralab, Sprague ( as
>used by Heathkit) and other 1000pf/5KV doorknob capacitors...they are
>all in the 220-240MHz range.
>>> as I use in parasitic suppresor
>>>circuits on 6M along with MuMetal as the inductor.
>>
>>Mu metal is more resistive than copper, however, there are much more
>
>>resistive alloys.
>More is not always better. At 330 Ohms/circular mil-foot, a Thermal
>Conductivity of only .14, and a 2650 degree F melting point it does
>the job and doesnt even get warm.
>>>BTW, I work on Millimeter Wave stuff daily in my real job and you
>>better
>>>believe we even have parasitics at 40 GHz ! The cure is often a
>very
>>>small application of solder on a gold plated trace at the input or
>>output
>>>of one of the TX stage amplifiers. It has almost no effect ( about
>
>>.2dB)
>>>at the desired TX frequencies but certainly shuts down all those
>>little
>>>spikes on the HP-8565E Spectrum Analyzer.
>>>
>>Interesting, Carl. Tin/lead certainly has more R than gold.
>Yep, a little disruption goes a long way....solder is simple and cheap
>in the above application. Once I tame the beast then I go in with tiny
>little pieces of gold to tune for gain specs, return loss, etc.
>Working under a microscope can be fun. Working with ones head where the
sun dont shine is not.
>73 Carl KM1H>
>>Rich...
>>
>>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>>
>>
>>--
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>>Problems: owner-amps@contesting.com
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>>
>>
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