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Author Topic: Parasitic Suppressor  (Read 2139 times)
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K9DXL
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« on: June 13, 2015, 01:49:49 PM »

I managed to toast the parasitic suppressor on my Hammarlund HX-50.  It's a 47 ohm, 1 W carbon comp resistor with 5 turns of wire around it.  My questions:  Searching on Digi-Key, I can find 1/2 W carbon comps, but not 1 W.
How critical is the resistance value?  Can I parallel two 100 ohm resistors and use the same number of turns?  Also, are the newer type carbon film resistors at all usable for this application?  Thanks in advance for your help!
73,
Jim
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Breathing solder fumes since 1959.  That explains a lot.
w4bfs
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« Reply #1 on: June 13, 2015, 02:10:32 PM »

the resistance value is not critical but if too high may tend to over dissipate ... if I had to use a multiple of smaller resistors I would use 3 150 ohm 1/2 w carbon comps .... be sure to check the actual value of the resistors .... carbon comps tend to go up in value due to corrosion of the tinned wire leads to carbon plug connection .... spme of the mfgrs were better at this than others .... you can re-use the wire wrapper from before even tho there less turns

when you finish be sure to check the stage with a neon bulb held near the plate circuit (careful - shock hazard )
if it glows purple, you have more parasites to get rid of 
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KD6VXI
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« Reply #2 on: June 13, 2015, 06:56:00 PM »

MOF (metal oxide film)  are fairly non inductive,  at least the 2 Watt and down.   Never had a problem using a 2 Watt MOF R at ten meters,  until I went overboard and used 5 watt units.  Those,  quite inductive.

MOF are fairly readily available,  as well.

--Shane
KD6VXI
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