Hi Vic, That is not surprising to me for reasons later discussed here... When something is rated at "1500 Watts, CW", that really means, 300 watts to 500 watts DC, or 100% duty cycle... I wish manufactures would rate things at 100% duty cycle. I am pretty sure Elecraft does.
CW is taken to be about a 20% duty cycle, (for the most part), and as such you can hammer something much harder when running CW than say when you are running RTTY at 100% duty cycle... That is how the 300 watt figure came about, r=.20*1500, where r is the rating for power. I tend to de-rate everything 60% to 85% when I run RTTY, PSK, or any mode that is even close to 100% duty cycle, more on the 75% side of things. I would bet that 1000 watts RTTY for 10 minutes would blow another trap... I really dislike trap antennas for this reason, and these reasons-- a bug gets into a trap, and you have a fire, water gets into a trap, and you have a fire, a leaf falls on a trap, and you have a trap fire, etc. You get the picture... Pretty much everything ends in "trap fire". Next time try and get an antenna with no traps if possible. I realize you have the R8 now, and will keep it, but in the future, never forget the lesson the MFJ antenna just taught you! I learned my de-rating lesson in a similar way several decades ago, running RTTY, I have NEVER forgotten it. If you have an antenna in a hard to get to location, overbuild everything. I had been considering an R8 up to now-- but the little experiment you just performed, just convinced me to avoid that antenna. -- Thanks and 73's, For equipment, and software setups and reviews see: www.nk7z.net for MixW support see; http://groups.yahoo.com/neo/groups/mixw/info for Dopplergram information see: http://groups.yahoo.com/neo/groups/dopplergram/info for MM-SSTV see: http://groups.yahoo.com/neo/groups/MM-SSTV/info On Mon, 2014-12-15 at 19:28 +0200, Vic Rosenthal 4X6GP/K2VCO wrote: > The good news is that I called MFJ, got a technician immediately, he > agreed that the 30M trap is the problem, and said he would send me a new > one under warranty. Elecraft-style service (so far). > > The bad news is that despite the statement in the manual that it is > rated at "1500W CW," he told me not to exceed 800-1000 watts. Not > Elecraft-style design/documentation! > > So if you have an R8 or similar antenna, be warned. I wasn't tuning up > or running RTTY -- I was calling CQ on 40M running about 1200W. > > Other bands are unchanged but 30 and 40M are gone. > > Thanks to everyone that responded. > > On 15 Dec 2014 15:07, David Cole wrote: > > Hi, > > > > No matter what happens, you will probably end up taking the antenna > > down... If nothing else to check to be sure it is fine... > > > > Grab an analyzer and connect it as close to the antenna base as > > possible, and see if it is resonant on all bands... Probably won't > > anymore. If you are lucky, it is some strange feedline thing, or a > > connector issue, but having the antenna work on some bands, while not on > > others reeks of blown trap. I fear your diagnosis is in fact > > correct... > > > > If you are going to "fix" it, and if it were me, I would get a trapless > > antenna of some sort... No traps blow. I currently use a GAP > > Challenger DX, (trapless), and have a band by band review of it at: > > http://nk7z.net/review-of-the-challenger-dx-antenna-by-gap-antenna/ > > > > The antenna takes power, and does not break, I have run 1000 Watts into > > it on RTTY for 15 minutes with no issues. I have had it up for at least > > 7 years, and I think 10 or more years. Never a problem beyond the three > > radials coming off once... It is a pretty good performer on 40, and 20. > > I finally got one of the mono gaps, and it does a good job. I do take > > it down every few years and check things, and change out anything that > > looks like it is going bad. > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
