[mdmars_members] Cascade Repeater

  • From: J Sears <aat3ok@xxxxxxxxx>
  • To: AIG-2 <mdmars_members@xxxxxxxxxxxxx>
  • Date: Fri, 2 Oct 2009 12:11:44 -0700 (PDT)

Good Afternoon All
As many of you already know the Cascade repeater is again on the air. We are 
however experiencing some problems.. some of which we knew about before hand 
and some we did not know about.  During the repair efforts you can still use 
the repeater IF you can get into it.
First, we have a carrier that a appears for a short (less than a second) period 
of time and then dissappears only to reappear 10-11 seconds later.  We have 
lengthened the key up delay on the controller and that helps to mitigate that 
for now. 
The source of interference is yet to be discovered but Gary has zero'ed in on 
it and from his place it is on a heading that is in direct line with Andrews 
I have asked Virginia Army MARS and AF MARS to see if they can use their beams 
to help us zero in on this signal.   Maryland members can likewise DF it and 
provide us with a bearing (and their location when taking the bearing) and we 
will plot these on a map. 
This will help us narrow down the area we must look in.  
Second, we have some kind dispatch operation going on the input freq. This 
interference source is in the clear and easily understandable so anyone copying 
this should either record it and send it to us or listen carefully for 
locations... names of places, companies etc. This is only part time which makes 
the effort to locate it very difficult.  We need each of you to note times and 
any other info you can about this interference. 
Third, we have some type of speach inversion transmissions appearing directly 
on our frequency.  You can identify this because it sounds a little like SSB 
signal that is way off tune or on the wrong sideband.  Litterally the speach is 
inverted. This appears to be something that is in close proximity to Site C and 
I do not believe it to be governent or military in nature because it is too 
crude for them to be using and provides little security. Just the same listen 
up on the repeater output to see if they ever change over to clear voice or any 
other distinguishing chararteristics you might be able to ascertain.
Of immediate concern to Gary and I is the fact that when we transported the 
repeater to the site, we did so in the back of AAT3GI's truck.  Unfortunately 
this (we think) jostled the duplexer sufficiently that it knocked it out of 
allignment and there is now a significant amount of receiver desence occuring 
in the repeater.  This prevents us from performing our normal control 
operations and necessitates someone going up close to the site to control the 
repeater.  Meaning we can turn the PL on and off without being close to the 
repeater and we cant just turn the PL on and leave it becasue we need to know 
when the signal is there to DF.  Ya just cant win can YA??
This is important becasue the DC repeater (which is on the same output 
frequency) has a net on there each evening during the week between 7pm and 10pm 
local time.  
Therefore DO NOT USE THE REPEATER BETWEEN 7 AND 10 PM during the week. 
In the next week or two we will be trying to track down the source of 
interference and also replacing the duplexer with one that is correctly tuned. 
Please be patient.
Anyone that would like to assist in DFing these signals please contact me by 
phone.. and lets talk.  I will provide you with the design for a portable 
antenna that will be great for the task and it is very easy to make. 
I would also like to thank Virgina Army MARS and our brothers in Virginia AF 
MARS for their assistance and especially AF MARS for their patience while we 
work these issues.  
Maryland State MARS Director
U.S. Army MARS


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