Go Back  PPRuNe Forums > Ground & Other Ops Forums > Engineers & Technicians
Reload this Page >

IFR NAV-750 and 401L To/From

Engineers & Technicians In this day and age of increased CRM and safety awareness, a forum for the guys and girls who keep our a/c serviceable.

IFR NAV-750 and 401L To/From

Old 5th Jun 2021, 20:45
  #1 (permalink)  
Thread Starter
 
Join Date: Apr 2009
Location: Phoenix, AZ
Posts: 90
IFR NAV-750 and 401L To/From

I recently used my NAV 401L and NAV 750 test sets to diagnose and repair a couple of KX-170B and a couple of KI 201C Nav Indicators. I had previously only used these test sets for on aircraft equipment testing.

On aircraft both test sets give correct To/From flag sense. However, when the Nav indicator is driven directly by the composite modulation output (rather than using the modulated RF output and an intermediate receiver) the To/From flag sense is reversed. I didn't realize this when I worked on the first KI 201C and spent a lot of time looking for a non existent fault.

This sense reversal is not mentioned in the manuals for the IFR 750 or the NAV 401L. Does anyone familiar with these test sets know where this To/From flag reversal is documented?
EXDAC is offline  
Old 26th Jun 2021, 09:37
  #2 (permalink)  
 
Join Date: May 2021
Location: berlin
Posts: 3
I can see taking care of flight and enroute on a sear nav radio/VOR pointer on the off chance that you plan effectively. That leaves the methodology as the most hard to sort out with just a solitary VOR. Are there any? At long last, when documenting IFR, you don't record a particular methodology, so is it legitimate to anticipate a visual if the climate is conjecture to be sufficient for it? This way I figure I could design a basic course requiring just a single VOR.
Reloald is offline  
Old 27th Jun 2021, 06:00
  #3 (permalink)  
Moderator
 
Join Date: Apr 2001
Location: various places .....
Posts: 6,716
Probably get more results here than in Tech Log ?
john_tullamarine is offline  
Old 8th Jul 2021, 22:57
  #4 (permalink)  
Thread Starter
 
Join Date: Apr 2009
Location: Phoenix, AZ
Posts: 90
Originally Posted by john_tullamarine View Post
Probably get more results here than in Tech Log ?
No reply or unrelated gibberish, not sure which is less helpful. The IFR NAV 750 was a standard test set on many avionics test benches so it's hard to believe that no one except me noticed this flag sense reversal.
EXDAC is offline  
Old 10th Jul 2021, 12:20
  #5 (permalink)  
QA1
 
Join Date: Apr 2008
Location: UK
Age: 66
Posts: 78
This info may be relevant or not.

https://upperlimitaviation.edu/vors-...-to-from-flag/
QA1 is offline  
Old 11th Jul 2021, 02:15
  #6 (permalink)  
Thread Starter
 
Join Date: Apr 2009
Location: Phoenix, AZ
Posts: 90
Originally Posted by QA1 View Post

Not, but thanks for the reply.

Both test sets allow generation of a To flag, or a FROM flag on any test bearing. When received as modulated RF the flag sense on the instrument is as sent by the test set. When received as the raw modulation signal the sense is reversed. This has nothing to do with student pilot inability to understand the meaning of TO/FROM flags. It appears to be an undocumented phase reversal in both test sets.
EXDAC is offline  
Old 22nd Jul 2021, 02:36
  #7 (permalink)  
 
Join Date: Sep 2013
Location: Canada
Posts: 45
Don't know about your KI-201C but some VOR converters require reverse phasing.
E.g. the KX72 described here has 3 composite inputs, one that wants standard phasing and two reversed.
m39462 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.