[GreenKeys] Fredericks LEM-1

[Duncan Brown]

And now back to the LEM-1

Thanks, Jack - you seem to be the only one who has seen a LEM-1. 
Probably the Fredericks 1280 M&S outputs that would drive the external 
scope drove the LEM-1?  Any idea what the "DIV" button in the front 
panel is for?  My first thought was "diversity" but that wouldn't make 
much sense in a BER tester unless it could show you the improvement to 
the BER in diversity mode.  But don't see any diversity output.

I stated previously that  there was   "No controls for data rate or 
number of bits. "
I opened the unit and there are dip switches (accessible by removing the 
front panel) and lots of jumpers for selecting input impeadance and 
output data format (232 & 188), plus many more unlabeled. The MIL-188 
data interface implies they were looking at the government market with this.

There are 16 dip switches for each link.  4 are for "MODE"  and 12 for 
"BAUD RATE".  The Baud Rate switches are divided 4 each for "H", "T", 
&"U" (Tens, Hundreds, Units), so LEM-1 could apparently do any baud rate 
up to 1599.  This unit was set for "600".  We got it with a Dovetron 
MPC1000 (with real CRT) in a small rack with home-brew loop & audio 
source selection switch panel, so I had assumed the LEM-1 was used with 
Ham RTTY.  But since it was set for 600 baud, I guess the former owner 
was still trying to figure out what to do with it and/or just thought it 
looked cool in the rack.

Duncan
K2OEQ

On 01-Dec-13 19:50, Jack Hart wrote:
> I had one of those...it's a bit error rate counter for two channels.
> I believe it was used with two Frederick Plantronics 1280 modems.
>
> Jack K0TTY
>
>
>
>
> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net
> [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Duncan Brown
> Sent: Sunday, December 1, 2013 6:47 PM
> To: Green Keys
> Subject: [GreenKeys] Fredericks LEM-1
>
> Anyone know anything about the Plantronics/Fredericks Electronics LEM-1 Link
> Enhancement Module??
>
> Looks to be a 2-channel BER tester, maybe with diversity?
>
> It has "Mark & Space" Analog Inputs and "Data, MBC, Q, & GND" for Data
> Outputs.  No controls for data rate or number of bits.
>
> Photos enclosed.
>
> Only thing I could find on the Internet was someone selling a manual & data
> sheet, but listing was 11 years old & his email address doesn't work
> anymore!
>
> Thanks,
>
> Duncan
> K2OEQ
>
>
>
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