The QST article achieves the X2/X5 scales by putting resistance ACROSS the 30uA meter. This is fine if your meter is reading too high, but it won't help if the meter is reading too low. And, of course, the calibration would only be good for the particular element you're running at the time. When you put in a different element, the calibration could change. Best thing to do if you really need accuracy is to remove the nameplate from the element and tweak the pot inside, using another known accurate power indicator and source.
Bob M. ====== --- Ron Wright <[EMAIL PROTECTED]> wrote: > At 5% accuracy the Bird 43 aint all that accurate, > but has been the industry standard. But for 2-way > work which is long way from high tech it is good > enough. > > The QST mod article is good and does allow for some > calibration since adjustable. They simple put pots > in line and adjust for whatever power level one > wants. Bird does same with fixed resistors, but > wants you to buy slugs. > > 73, ron, n9ee/r > > >From: Doug Bade <[EMAIL PROTECTED]> > >Date: 2007/08/13 Mon PM 12:49:00 CDT > >To: [email protected] > >Subject: Re: [Repeater-Builder] Bird Wattmeter > X2/X5 Range Switch > > > > >I have a Bird 4410A which has a range selector > switch ( rotary) but > >have never seen a modified 43... maybe an amateur > mod??? Calibration > >certification would seem to go out the window... > > > >Doug > >KD8B > > > >At 01:17 PM 8/13/2007, you wrote: > > > >>There's a modification to the good old Bird 43 > >>wattmeter that adds an X2/X5 switch. I suspect > this > >>just shunts the meter movement with pots. One > person > >>was selling such a meter on eBay and claims the > mod > >>was seen in a magazine. > >> > >>Anyone seen this mod, or know where it was > printed? > >> > >>Thanks. > >> > >>Bob M. ____________________________________________________________________________________ Looking for a deal? Find great prices on flights and hotels with Yahoo! FareChase. http://farechase.yahoo.com/
