Friday, June 14, 2013

BYRG Technical Meeting 13 June 2013

Well another BYRG Technical meeting came and went, but this one had some actual work take place.

Work you say! Yes, work. Some pictures to follow later in this installment.

Phillip - KDØIXY, Making some "adjustments", ....  NOT!
Jeremy- KDØEAV could not make this one due to some family medical issues, we 
had Chuck- KØXM, & Phillip - KDØIXY and of course DrSmØke - WØNQX. 

The Meeting was held at "The Facility" on Troost Ave Thursday Evening. These meetings are held periodically so we can get technical stuff done for the BYRG repeater group. Held mostly on Thursday nights, since that seems to be the only day we can get all of us together at one place and at one time.  

We used to hold Tuesday noon lunch meetings in NKC, as the tacos were great and cheap! We have not had one of those in some time, we may be overdue on that one. :)

Well back to the work at hand. about 2 years ago one of our group members bought a large, very heavy Motorola surplus MSR2000 UHF station from the local "batwing" shops' mini-ham-fest held in conjunction with the annual Metro Shriner-fest, since they are right next door the the ham-fest location it is only natural they hold a mini sub-fest at their place. 

Well anyhow this big upright got pawned off on us as a good candidate to replace the aging 442.5500 BYRG Flagship repeater down on the Commerce bank tower, downtown KCMO. 

Chuck- KØXM sent the rocks off in March to ICM in Ok-City for a slow re-rock of the ICMs, yes I said slow, with rock bound repeaters you don't want overnight crystals made, you want them done sloooow, that way they are most stable when you install them in your repeater.  ICMs are Integrated Crystal Oscillators.
Here is a plug for International Crystal

The ICMs are installed and are on frequency! YAY! :)
We got the excess parts removed, Chuck- KØXM had the MSF documents from 
the Repeater-Builder site printed on "Old-Man" sized paper for us old guys to see the jumper tables. 
I am just glad he did not print in size A! :)

Now on the the set up part... one thing we did not have was a TRN5080 test box for proper tune up of the receiver and exciter basic stages.  So we did it old school way with a spectrum analyzer and very careful tuning. We started with the transmitter exciter, first we checked for ICM crystal activity. We found we had a 
to install a couple of jumpers to make the unit active. After adding the correct jumpers we had a nice strong
ICM oscillator signal 12.293 Mhz it was about -60 dbm. 

Then we added a gator clip for the PTT line and went thru the stages and tuned for peak. We ended up with a -45 dbm on frequency 442.5500 Mhz signal. We stopped at this point on the transmit side since we did not have the PA and the time for final pre-selector stage setting for the transmitter. 

We moved over to the receiver side installed the ICM and the appropriate jumper to make the receiver active. We got kind of worried when I could not see a 48.538 Mhz signal from the ICM can. 

But after a quick math class 447.5500 - 10.7/3 =  145.6166 , we looked at that frequency and we had a nice -55 dbm signal there. We proceeded on to tune the front end and IF sections and at the end we got a 0.2uV over all receiver sensitivity for about 12db sinad. 

Now our young protégé, Phillip - KDØIXY was taking all this in and wondering what these 2 old guys were getting all excited about, of course he had read the instructions from Repeater-Builder site and wondered how we did all this without the TRN5080 test box. Very carefully we said. 
We should try and get one of these units.
The important thing is that we had a spectrum analyzer to go through the stages with, ultimately we will go back through the sections with the proper test box before final deployment to make sure we are on the correct peaks and valleys, as we want to get all we can out of our replacement repeater. We have it now to the point were we can add the controller and start the point to point wiring for that part of the upgrade.
And it will let us do some testing as we add the Asterisk based VoIP repeater controller to the mix.
UHF MSR2000  The new 442.5500 Repeater

Psssst! Anyone want to buy some used radio parts?

Chuck- KØXM

Phillip - KDØIXY

All For Now
Comments Invited


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