Clear Across Kansas

Minneapolis 444.850 repeater now with System Fusion Digital!

UPDATE June 29, 2016: Text updated below.

  • RLC-MOT and TS-64 boards have been removed and replaced with the Repeater Builder SC-50 board.

The SC-50 board has a Motorola Micor squelch and an FX465 CTCSS decoder/high pass filter built-in. This simplifies the interface between the DR-1X and the S-Com 7330 and provides better CTCSS attenuation in the audio path.


For my second DR-1X modification, I removed the internal power supply and mounted the SC-50 board so that the DB-25 connector is accessible from the rear, as seen below:

sc-50 top

sc-50 rear

The following notes still apply:

April 11, 2015 (Original post)

Justin NV8Q and Chuck N0MXI installed the new Yaesu DR-1X Digital Repeater to replace the GE Mastr II repeater at the Minneapolis site.  This repeater is setup in mixed-mode (Yaesu calls it Auto Mode Select). Digital transmissions will only be repeated locally on the 444.850 repeater, and will not propagate to the rest of K-Link.  Analog transmissions using PL 162.2 will be repeated locally and to K-Link just like normal. The repeater is running 90 watts (the old one was 55 watts).  The DR-1X is running in ‘Open’ DSC mode so any digital DSC code will pass through.


If you don’t have a Yaesu digital radio (you are missing out!), you will want to use Tone Squelch (CTCSS decode) on your radios so that you can eliminate the digital noise you would otherwise hear if somebody is using digital. Tone squelch eliminates all this noise without missing analog calls.  If you need help setting up your radio please ask us to help!

Our particular DR-1X repeater has had some really nice modifications to it:

  • Masters Communications SC-50 Squelch/CTCSS board. This provides superior squelching action with reliable CTCSS decoding and filtering.
  • 200 watt Henry amplifier, de-rated to 90 watts. This requires about 11 watts of drive.
  • Custom S-Com 7330 wiring interface and programming script to make the DR-1X available to analog and digital calls with minimal interruption.

This repeater will process analog or digital calls while it is idle.  During a call, it will be expecting (and will only process) whichever mode is currently being used.  During a digital call, if a user un-keys and the repeater becomes idle for two seconds, it returns to idle mode and is available to digital or analog calls. During an analog call, the repeater holds analog mode active for six seconds.  This hold makes the repeater more available for conversations across the linked system.  During an analog call, if one user un-keys and the other user doesn’t reply within 6 seconds, the repeater enters idle mode and is available to digital or analog once again.

It should also be noted that if the repeater is idle, it takes about 1/4 second to key up at the beginning of an analog call.  You can bring the repeater up in analog mode by keying your mic for one second before talking.

During Skywarn Net operations, digital mode will be disabled.

Instructions on how to interface the S-Com 7330 to the Yaesu DR-1X (without using the Arcom ADR) can be found here.



Have a Question or Comment?

21 comments on “Minneapolis 444.850 repeater now with System Fusion Digital!

Very nice. Nice work on the repeater. Nice website. FYI, we have a Fusion net on 444.525 (W0MDT) Monday nights at 7:30. Would be cool if we could figure out how to link. I’m currently working on a project that will allow simulcasting FM/Digital on the 444.075 – which uses an Scom 7330 and physically sits right on top of the DR-1.

Chris, K9EQ

Justin Reed - NV8Q

Chris, when Yaesu releases the firmware update that allows Wires-X to be connected to the DR-1X in digital mode, I plan on integrating that to this repeater as well. Or I might re-work that idea, and do an analog Wires-X link directly to the 7330 controller so that our entire link system has access to Wires-X. I’m a little ways off from that, though.

Billy KA2BYU

I read the comment on Yaesu System Fusion Group regarding the DR-1X connected to an S-Com 7330 controller. I look forward to any info you post.

My immediate questions are:
1. how do you reduce the power output of the repeater down to 2.4 watts?
2. Does this violate the warranty?
3. Is 2.4 watts the max to drive the MSF5000 amp, I was planning on using 1.25 watts (6 dB attenuator). Is this to little?




Search the web for “DR-1X Technical Supplement”. That document has the alignment instructions. You’ll need the FTM-400 control head and mic plugged in to the DR-1X’s transmit radio to complete this. It probably does not violate your warranty unless you screw up the alignment, then they will charge you to fix it.

Every MSF5000 amp will be a little different, and the power output you get will depend on the input DC voltage. But 2.4 watts is an approximate figure in any case. And you need a 3db attenuator to drop form 2.4 to 1.25 watts, although the MSF5000 amp will not make power at anything less than 2 watts.


Alan Pearson, KB6DMZ

We have just recently received our DR 1x repeater. Can recommend a low cost duplexer?


Don’t skimp out on duplexer, antenna, or feedline. The repeater is going to be the cheapest part of the system. Go with a band pass/band reject duplexer. An example on eBay currently is found here:

The cheapie band-reject duplexers that the Chinese are selling for $75 do not provide any bandpass filtering which is going to cause problems with the extremely sensitive receiver of the DR-1X.

Good luck!

John Probst - KA8RVI

Was reading your Interfacing the Yaesu DR-1X…. version 2 document & under the Optional (but highly recommended) Items: you listed a 12V DC cable of 20+amps with flyback diode across the coil. Could you recommend where to get these items as well as pt#?
73’s & Tnx,


The relay could be this one:

Use a diode across the coil contacts with the cathode on the positive terminal to suppress voltage spikes when the coil is de-energized.

73, Justin NV8Q

Ralph McNall


Does the following imply that you have to use either CTCSS or or DCS to access the analog FM mode?:

The SC‐50 will be used to supply the 7330 with CTCSS decode logic that is independent of valid digital signals.  This is required because Pin 3 on the DR‐1X goes active if there is
valid CTCSS/DCS/Digital activity.   We need a way to distinguish between analog and digital signals, and in FM mode CTCSS is the only thing we care about….

Note: If you want to use DCS, you’ll need to follow the same advice pertaining to the DR‐1X’s DCS setting (use an odd code nobody knows about) and instead of using an SC‐50, obtain and use a DCS‐23 and MS‐25 squelch board and follow the wiring diagram on page 10.


Yes. In theory, the script could be modified for carrier access if you add a COR delay filter, but that is untested and I don’t recommend it.
The reason is if the DR-1X is configured for carrier access in analog mode (even with the 7330 script), you will frequently find situations where a digital user on the fringe of the receiver coverage will drop to where the digital stream cannot be decoded but the signal is still sufficient to trigger the analog squelch, causing the repeater to suddenly go into analog mode and then back to digital when the incoming signal increases to the point that it can be decoded again. This will lock up the PTT logic on the repeater, and can only be remedied by power cycling the repeater.

Using CTCSS or DCS eliminates this artifact.

Justin NV8Q

M. Gasser KA8WPC

Will the Motorola msf5000 take the 5watt output of the Fusion without attenuation to the amp input?


At 5 watts the UHF MSF5000 PA will be driven to full saturation, which is beyond it’s 100 watt rating. You could “dial it down” by reducing the A+ voltage to the PA until you reach the desired output, if you have a variable power supply.

Mike Gasser

won’t a 3db attenuator work in dropping the 5 watt output of the dr1x to about 2 watts to drive the amplifier?


Yes, if you have one rated for 5 watts continuous.


Post updated with new info.


Hello, Our club will replace our old repeater with a new Fusion. On VHF the amplifier Motorola 2601A requires only 400 mw from specs to drive. Any one using the Fusion with a low drive amp, Thanks Mike, KN9T


Mike, I have been able to use the alignment procedure to reduce the DR-1X output down to 1/4 watt for a GE Mastr II PA. Search for the DR-1X Technical Supplement and it will describe the process for changing the power settings for each of the three setpoints for each band.

mike OConnor

thanks Justin. would only want to reduce the low 5 setting to 400mw on one vhf fusion and 2 watts on another UHF. can this be done without touching the med. And high settings. 73 Mike KN9T

K2KGJ, Jules

Hey guys, help me out here. We have two DR1X repeaters, one had version 1.10D the other 1.00F. Tried both on an Arcom RC-210 with ADR. Seemed to work OK except for occasional lockups. One thing was no FM audio on the monitor speaker with external controller; digital audio was heard on monitor. Even though FM audio path was through external controller, would have expected speaker audio.
Most recent problem: the 1.10D machine suddenly dropped FM repeat audio to ~25% of normal dev. Expecting a problem with the DR1X, replace it with the 1.00F unit and audio came back up so not the RC-210 level.
When bench testing the 1.10D removed from service, couldn’t get it to work with remote OFF until I did the factory default reset. In local mode, FM and Digital audio levels fine and all modes heard on monitor speaker. Then upgraded to 1.10Q firmware, Main and DSP, and configured the repeater for remote to put back in service. Back in service on the RC210, the FM repeat audio level on the upgraded machine was still low (huh ???) so trimmed up level with the RC210 pots.
And, when remote was turned OFF, with all controller cables disconnected, same symptoms as with the previous 1.10D firmware … couldn’t get it to work in local until I reset to factory default. Simply turning remote ON and the OFF didn’t cause the anomaly but only one remote Tx cycle was needed to put it in the same state. WIERD ?
Any thoughts … does your machine do this on the 7300? Or maybe you haven’t tried to run local again after setting up the remote.


Jules, let’s tackle these issues one at a time.

First, the local speaker on the DR-1X will not “work” when you’re using an external controller with ADR, because remember you set the DR-1X internal configuration to a CTCSS/DCS tone that is NOT in use so that the internal control remains dormant so the external controller can do it’s thing. The local speaker will only unmute when the internal config criteria are met. For example, during a digital conversation that matches the DSQ setting or an analog conversation matching the internal CTCSS/DCS.

Second, the reason your audio levels changed when using the external controller is likely because you inadvertently set the DR-1X to 9600 bps packet mode, rather than leaving it at 1200 bps. The difference here is that the transmitter applies the 6 dB per octave pre-emphasis curve to the transmit audio path in 1200 bps mode. It leaves the transmit audio path “flat” in 9600 bps mode. Note that this does not affect C4FM operation in any way. See your manual for instructions on how to change the packet mode.

Then your comment about the repeater locking up after using the RC210 and transmitting for one cycle leads me to believe that you forgot the need to set the DR-1X config to a NON-USED DCS code for analog.

Does this address the issues?


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