Message-ID: <3CB02BD3.20100@nidlink.com>
Date: Sun, 07 Apr 2002 04:21:55 -0700
From: Hamid Wasti <hwasti@nidlink.com>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:0.9.4) Gecko/20011019 Netscape6/6.2
MIME-Version: 1.0
To: lancair.list@olsusa.com
Subject: Re: Ritchie Electronic Compass
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
Reply-To: lancair.list@olsusa.com

          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> 
>>
Jim Cameron Wrote:
 >The Ritchie compass looked very attractive when I was designing
 >my panel -- new technology, no precession, light weight, and quite
 >inexpensive (about $260, as I recall).

Sound familiar?  We have talked about lots of quite inexpensive and high 
performance avionics.....

 >After some flight hours with it, however, I elected to replace it
 >with the old-tech RC Allen model.

You can learn from Jim's experience, or you can try it for yourself. 
 The choice is yours.  Maybe you have the power to claim an exception to 
the laws of physics & economics.  You will never know till you try.

 >when you key the mic to transmit on your COM, the Ritchie compass
 >goes nuts (along with the E.I. fuel gauge). Seems that neither of these
 >instruments like stray RF.

Before I continue, let me do the usual disclaimers regarding my 
affiliation with Sierra Flight Systems.  Brent Regan and I have designed 
the hardware for the Sierra Flight Systems' EFIS products and are 
working on the certification program for the EFIS.  Just a few days ago 
I was reviewing the costed bill of materials for the custom designed 
EFIS board and was surprised at the significant cost of components whose 
sole purpose in life is to deal with stray RF, both the kind that you 
get when you key the mike and the kind you get from a bolt of 
lightening.  Obviously I can not talk about specific numbers, but 
suffice to say that SFS is spending more on components to handle RF than 
some competitors may be spending on their entire hardware.  That is the 
difference between hardware that is designed specifically for the 
aviation environment versus slapping together hobbyist components into a 
"new technology, light weight, state of the art, quite inexpensive" system.

You can have low cost hardware or you can have reliable hardware.  You 
can have either, but not both.  As I said earlier, the choice is yours.

Hamid


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
LML website:   http://members.olsusa.com/mkaye/maillist.html
LML Builders' Bookstore:   http://www.buildersbooks.com/lancair
Please remember that purchases from the Builders' Bookstore
assist with the management of the LML.

Please send your photos and drawings to marvkaye@olsusa.com.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>