Yes, its certainly possible a piston capacitor could be damaged due to lightening, but I'd think this would more apply to a "direct hit" scenario. It'd also be very apparent during tuning and would likely have a profound impact on system performance. There are also many cavites that don't utilize a piston capacitor for reject notch, i.e. many of the popular Wacom BpBr vhf duplexers: WP-641, 642, 643 etc.
Dan K8PLW Livonia, MI --- In [email protected], "Eric Lemmon" <wb6...@...> wrote: > > Since the typical BpBr duplexer uses an adjustable capacitor to tune the > notch, I would think that one or more of those capacitors would be the most > likely component to be damaged by a lightning-induced surge. For example, a > Sinclair Q202G duplexer uses Johanson piston capacitors which have extremely > close tolerances to achieve values of 10-30 pF. A digital capacitance meter > could be used to measure the value of the notch tuning capacitor in each > cavity, to find one that is out of family. > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of dan173mi > Sent: Wednesday, January 20, 2010 8:43 PM > To: [email protected] > Subject: [Repeater-Builder] Re: follow up on lightning strike last spring > response > > > > Most duplexers are passive, mechanical devices. You did say the cavities had > been visually inspected and cleaned so we can assume the "cans" themselves > are fine. In my opinion the single component on a duplexer that's most > likely to fail would be the cable harness and its associated > connectors/adaptors. Is this a vhf repeater? What is the power output? > > Dan K8PLW > Livonia, MI > > --- In [email protected] > <mailto:Repeater-Builder%40yahoogroups.com> , "Richard" <rranta@> wrote: > > > > Sorry if I've been late in posting. First, the antenna and hard line is > ok. We've tested that part out and its working. We think ( I ) that we got > zapped through a unused phone line which is mounted behind the repeater > rack. > > Yes, we have tested the can's using both a IRL (?sp) and a General > Dynamics service monitor. They were taken apart and cleaned and retuned. > Everything indicated they were functioning normally. Till we put them back > in service. I don't know if they were tested with a dummy load. The > technicians made many trips to the site: the technicians worked for the > company that we rent the site from. We replaced all of the connectors and > only found one that had scorched indications on it, but that was all. > > I asked if any of you knew how to find out if a can was operational, > because all the test equipment that was used indicated they were ok. We > finally found a workable solution. We added a fifth can, tuned to the > transmit freq. That stoped the crackling noise. > > Now we're going to replace the can's, and go with a 6 can configuration. > this is what was reconmended by the technician. > > > > Rich K8JX >
