The only grid protection that seems to protect a 3-500Z reliably is a
fusable element --such as a 0.5A, 3AG fuse or a 20 - 39 ohm 1/4 or 1/2
watt carbon-film R. While transistor-type protection circuits look
good on paper, they tend to fail C-E shorted when presented with the 10
or so ampere spike in grid current during a parasitic event at 95 -
120MHz. . . Sometimes mo' simple is mo' betta.
On Jan 17, 2005, at 4:48 PM, Charlie wrote:
The AL-80B manual and web site discuss an "optional' grid protection
board I believe they call it. I am the new owner of a used AL-80B and
would like to know how I can check if this "optional ' grid protection
is in place or not. As best I can tell this amp was new in 1997.
I have several photos of the inside on my site listed below. If anyone
can spot it or tell me what to look for I would be very appreciative.
I got on this matter after the amp kicked off a couple times on 40M
phone. After several moments it was OK again. I am guessing it was
this optional circuit. TY 73
Charlie
Ham Radio - AD5TH
www.ad5th.com
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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