[Milsurplus] USAFmodified APN 9 Loran A?

[BOEING377 at aol.com]

In a message dated 11/28/2005 1:06:35 AM Pacific Standard Time, 
milsurplus-request at mailman.qth.net writes:

> >I am  looking for information on a modified APN-9 Loran set.
> >This set used decade switches to read out the time difference values 
> instead 
> >of using
> >the internally generated markers.
> 
> Was this indeed a modified /APN-9, or are you talking about something like
> the later /APN-70?
> 
> William Donzelli
> aw288 at osfn.org
> 

The set was definitely an APN 9, called APN 9A (not R 65A APN 9). I actually 
saw the tech manual with real photos and extensive schematics. It looked just 
like an APN 9 but had decade rotary switches in a vertical column to set time 
delays digitally. No veeder root counters. It had tube based decade dividers 
arranged in modules. I saw the manual on a fishing boat that had a regular R 
65A APN 9 set aboard. The captain had a friend in the USAF who gave him a set of 
manuals which included a regular APN 9 manual and the intriguing APN 9A 
manual. I have NEVER run into anyone who knew anything at all about the mysterious 
APN 9A. The R 65A APN 9 was a fine Loran A set, but had a strange built in 
quirk that had a 100 microsecond error in the TD. You had to add 100 microseconds 
to any TD to get an accurate LOP. This procedure was explained in the 
operator manual. Anyone know why this built in error existed? APN 4 and APN 70 did 
not have it to the best of my knowledge.