[digitalradio] Re: Old MFJ 1272B TNC/Mic switch circuit or manual?

[Al Woodhull]

Dave's help was just what I needed, my thanks to others who
responded. As it happened I had disassembled the unit to take
pictures of both the bottom and top of the circuit board to help
me try to regenerate a schematic, so I was ready to send a picture
immediately upon reading Dave's reply.

73, Al N1AW
Amherst, MA

--- In digitalradio@yahoogroups.com, Dave wej ve3...@... wrote:

 I have several types here, can you email a picture of the inside for me
 
 Dave Garber
 VE3WEJ/VE3IE ve3...@... 
 
 
   - Original Message - 
   From: Al Woodhull 
   To: digitalradio@yahoogroups.com 
   Sent: Tuesday, April 21, 2009 11:30 PM
   Subject: [digitalradio] Old MFJ 1272B TNC/Mic switch circuit or manual?

   I have an old MFJ 1272B that I bought at a flea market. There have
   evidently been major changes in the design of units sold under this
   model number over the years. The manual that is currently available
   on the MFJ website is not useful for my older one. 
...

[digitalradio] Old MFJ 1272B TNC/Mic switch circuit or manual?

[Al Woodhull]

I have an old MFJ 1272B that I bought at a flea market. There have
evidently been major changes in the design of units sold under this
model number over the years. The manual that is currently available
on the MFJ website is not useful for my older one. 

These devices are configured for different radios and TNCs by putting
jumpers on header pins. The manual I found on line is for a rev. 8 or
9 unit that has 2 sets of headers with a total of 96 pins, but the old
unit I have has one header with 30 pins -- a totally different circuit. 

Can anyone point me to a schematic or manual for the older one? I
suspect mine is a rev. 1 unit, there is no visible rev. number on the
circuit board.

73,
Al Woodhull, N1AW
Amherst, MA