[Amps] Glitch resistors

[Ian White, G3SEK]

Peter Chadwick wrote:
>So out of the following, which would you recommend?
>
>1. 80 ohm, 100 watt carbon rod. About 1 inch diameter 12 inches long. 
>Originally
>meant as low inductance RF load resistors.
>
>2. 50 ohm, 100 watt wirewound. 1.25 inches diameter, 10 inches long, vitreous
>enamelled
>
>3. 50 ohm, 50 watt glass tin oxide, 1 inch diameter 6 inches long. ( 
>designed as
>low inductance RF load resistor)
>
>4. 75 ohm, otherwise as 3 above.
>
>Size/space is NOT a problem. My feeling is that any of them should do, but I'd
>be interested in comments. As these are all in the junk box, any alternative
>requiring expenditure needs well justifying!

Any will do from the glitch point of view, but the 50R ones will drop 
less voltage and generate less heat than the 75/80R ones.

50R is probably on the high side of the normal range of values, unless 
you happen to have a lot stored energy in the reservoir cap (very high 
voltage and/or very high capacitance).

The carbon or tin oxide ones are supposed to be the best because they 
have a continuous voltage gradient instead of going down in steps 
between turns, but when you're talking about 6-10-12in total length, who 
cares?


-- 
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
                            Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek