[AMPS] The Emtron DX2 amp: A 50ohm 50 Watt resistor in B+?

[Phil Clements]

At 09:31 PM 10/17/97 -0700, you wrote:
>Thanks Phil for the comments.
>
>BTW, you mention that some 'flash overs were so intense as to cause
>shrapnel into the rotary blower..." Is that really true???

Not shrapnel, Chris. The tremendous amonnt of power available in such a small
space can actualy vaporize internal windings and ruin bearings in the blower.
Putting a copper screen over the blower outlet would help prevent this, but
would restrict air. A trade-off between the coarsness of the copper screen
and RF attenuation would have to be made. If the current in the B+ line is
limited to >100 amps, the probability of major damage in the RF compartment
is greatly reduced, and shouls be all that is necessary.
>
>Pete Gerba told me that this blower is now over $2000 to replace!!! Is
>that true???

It very well could be. 90% of the parts in the 77 series are standard "off
the shelf" components. The blower, filter cap. and relays are not. Alpha
gets $898 for a replacement filter cap. Peter Dahl's unit is better, and is 
"only" $398!!

>
>I think I'll do the same w/my 77sx and go get that 20ohm 25 watt glass
>wound resistor down at our surplus stores here in Silicon Valley and put
>that near the filter cap (stock value cap).

If you have a space problem, 2- 10 ohm 12 watt units will work fine.

(((73)))
Phil, K5PC


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