I have burn up two output band switches on my Ameritron AL1200 while on 160m. The amp uses a single 3CX1200A7 tube. My swr may have been high, but less that 3:1.
Could the discussion above be the same for the AL1200 amp? I'm tired of replacing the band switch. I looked at replacing it with a larger switch, but there is not enough room. I am not an electronic tech, but I can understand most of the discussion/theory. Tnx, Ray, N6VR On Wed, Mar 19, 2014 at 9:12 AM, Tom W8JI <w...@w8ji.com> wrote: > Wrong reflector, but I disagree completely with this: > > > The HV build up was mitigated by the 10pf cap between the 40-20M >> positions which also reduces arcing on the SB-220 which is a shorting >> switch and a cap can be adapted to some 160-10M amps. The right hand one >> in that photo had the 80-40M contacts replaced and Id bet there was still a >> carbon track that wasnt removed, you can easily see the deposits all around >> that wafer; a good sign of a poor repair tech. Originally a sure sign of >> high VSWR or open relay. >> >> Same style wafers as in the SB-220, Clipperton L , AL-80 family and >> others that lived on the edge that still arc today. The arcing is usually a >> high VSWR, open circuit due to relay, way out of tolerance carbon parasitic >> suppressor resistors, mistuning as was likely the cause on the left wafer >> on 10M, and CB use since the NCL-2000 was one of their favorites in the >> 70-80's. Another cause is not knowing how to read the manual tuning >> instructions and tuning full bore key down in the SSB position. As built it >> was a 1000W INPUT CW amp and 2000W INPUT PEP on SSB. That is about >> 600/1200W output respectively as was common on many amps of the pre 1500W >> output era. Funny how they all seemed to be OK before the rules changed and >> switch configurations werent an easy way out to cast blame..... >> >> > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > _________________ Topband Reflector Archives - http://www.contesting.com/_topband