N5MBM Chappell Hill 220 MHz Repeater - Operational

  1.25 meters - 224.900 tx 223.300 rx with a tone of 103.5 -AllStar Node 42471 - Operational as of 07/04/2015

Currently acting as a "stand alone" repeater to facilitate local communications.

TYT TH9000D 220 MHz

05/15/2015 - I found some interesting documents talking about modifying TYT TH9000 radios for a repeater - Build a repeater from TYT- TH9000 Mobile Transceivers http://crompton.com/hamradio/BeagleBoneBlackAllstar/TYT_mod.pdf  I was intrigued, I had a couple of these Chinese radios.  I ordered the parts from Digi-Key and sat on my hands for a few days waiting for the USPS lady to arrive with my goodies.  The "modification" consisted of soldering up a little jumper cable for a 6 pin plastic plug to connect to the printed circuit board, wired to a little 9 pin serial connector you screw into the back of the radio under the heat sink (There's a hole there already!) attached to the radio with a couple of screws stolen from the outside bottom case cover.  It was a VERY simple mod!  It brings everything you need to interface with a repeater controller/IRLP node/other radio out of that little 9 pin connector.

6/25/2015 - We recently acquired several sets of "used and stored away for years" Remec-Wacom WP-747L3/447L1 duplexer cavities from Clay W8JVV after a rather interesting trip to Arkansas to retrieve them.  I did some research on these and the web holds very little information but I found KA1RCI had worked with these before!  Luckily he posted lots of info on his web site.  Here is what they looked like in their original configuration.

Remec-Wacom WP-747L3/447L1 Photo courtesy of KA1RCI

6/27/2015 - I changed it up from the factory configuration and arranged them like this photo below, after cleaning them up.  Sort of like the original configuration but I changed it up a little to make everything flow right and all the cables actually reach!  This is a 3x3 BpBr set, topped with a Bp cavity on the transmit and receive side to nullify noise.  8 cans in all.  This should allow me to run 100 watts with little to no worry of desense or spurious emissions coming in OR out. (I am hoping!)

Cavities mocked up and ready for tuning.    Cavities mocked up and being tuned with what I had on hand.


Remec-Wacom WP-747L3/447L1 220 MHz repeater duplexers - Cable lengths and tuning notes


Now I am trying to be patient until I get someone to tune them for me with the proper test equipment.  I tried tuning them myself using some test equipment I had on hand - just to get them close and see if they would work at all.  I found these instructions and ran with them.  I got them VERY close!  They work!  I got them so close I could probably put them on the air - but I am going to wait until they have been tuned properly and I KNOW they are "right"!

 06/30/2015 - After modifying a pair of my TYT TH9000 220 MHz radios, I hooked them up for testing and VOILA! They work!  Now I am using the 220 receiver as a remote base and listening to the IRLP nodes in Houston, listening to people from all over the country chatting - over my repeater now!  I tested the transmitter and I tested the receiver, and they both work GREAT! 

It's NOW fully functional!

N5MBM 220 MHz repeater    N5MBM 220 MHz repeater

07/04/2015 - I got brave and bold, I hooked everything up except the transmitter today.  Instead, I tried it with an HT in the transmitter port on 1 watt, then 5 watts - I saw nothing on the receiver.  Next I plugged in the transmitter on low power (10 watts), STILL nothing in the receiver when I keyed up the transmitter.  I bumped up the power to max (55 watts) - STILL nothing in the receiver.  Now, reality check, I don't know about desense, but it didn't pound itself with RF to the point that I didn't hear the hiss change on the open squelch!  So the cavities are awfully close if not dead on!  YAY!!!  (I still have some tuning to do, I am sure, if for anything it would be for less loss!)  Next I hooked up the controller...  I keyed the 220 side, the transmitter came up and I heard my 220 repeater, fully functional with TYT Chinese radios at approximately 5pm on 7/4/2015.  I was ecstatic!  I keyed up the 2m side and the I could hear it on the 220 side.  I keyed up the 440 side, and heard it on the 220 side.  The home-brew 220 repeater works like a charm!  AND now, all three repeaters work in concert now!  I am one happy camper right now...

Everything on this repeater is courtesy of ePray!  And I do mean everything!  From the antenna to the controller cable, everything attached to this came from sources on eBay.com

My paperwork is in!  I now have an official coordinated repeater frequency on 220 MHz!

The power got bumped up to 25 watts and we now have 15-30 mile coverage!

11/19/2015 - Now using a Comet CX-333 Triband VHF/UHF antenna with 7.8 db on 1.25m. at 35ft. AGL.


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