• To anyone looking to acquire commercial radio programming software:

    Please do not make requests for copies of radio programming software which is sold (or was sold) by the manufacturer for any monetary value. All requests will be deleted and a forum infraction issued. Making a request such as this is attempting to engage in software piracy and this forum cannot be involved or associated with this activity. The same goes for any private transaction via Private Message. Even if you attempt to engage in this activity in PM's we will still enforce the forum rules. Your PM's are not private and the administration has the right to read them if there's a hint to criminal activity.

    If you are having trouble legally obtaining software please state so. We do not want any hurt feelings when your vague post is mistaken for a free request. It is YOUR responsibility to properly word your request.

    To obtain Motorola software see the Sticky in the Motorola forum.

    The various other vendors often permit their dealers to sell the software online (i.e., Kenwood). Please use Google or some other search engine to find a dealer that sells the software. Typically each series or individual radio requires its own software package. Often the Kenwood software is less than $100 so don't be a cheapskate; just purchase it.

    For M/A Com/Harris/GE, etc: there are two software packages that program all current and past radios. One package is for conventional programming and the other for trunked programming. The trunked package is in upwards of $2,500. The conventional package is more reasonable though is still several hundred dollars. The benefit is you do not need multiple versions for each radio (unlike Motorola).

    This is a large and very visible forum. We cannot jeopardize the ability to provide the RadioReference services by allowing this activity to occur. Please respect this.

UHF Maxtrac repeater W/ TP-154 emits squelch burst at mobiles unkey

Status
Not open for further replies.

eportel6607

Member
Joined
Jan 1, 2012
Messages
112
Location
South County, Rhode Island
Guys I have four low power (under 20 watts) GMRS repeaters. They are all made up of Maxtrac 25 watt two channel models. The controller is a CSI TP-154 with two tones/users enabled.

Prior to using the tone panels I was using a simple repeater controller that worked well. In this configuration the PL encoding and decoding was simply programmed into the radios themselves. Since the two channel Maxtrac don't have the 16 pin logic board with all the necessary signals available I need to modify the radios to have the necessary signals at the mic jack. I've done this many times before but this is a bit different. In the passed I've really only need to get the COR signal to the mic jack. No big deal. I usually use the unused mic pin2 for this and grabbed the signal from the "RX Mute" circuit. The RX audio was taken from mic pin 8 which is "handset audio".

I can't use this method when using the tone panels for a few reasons. One, the handset audio is filtered...so the PL tone won't get passed to the tone panel and Two, the tone panel needs to be able to inject a PL tone into the transmitter...so the Maxtrac had to be modified.

Since there are only two pins in the Maxtrac's mic jack that aren't used (pin 1 and 2) I had to re-purpose a pin. I modified pin 8. As I said, this pin is normally filtered "handset" audio but I needed this pin to be used as an input for tone injection to for the transmitter radio. I severed the header pin from the front panel headers (J8) and made the necessary connections to make pin 8 function as needed. This part seems to work perfectly.

The issue is when a mobile/portable uses the repeater and unkeys it's transmitter the repeater has a long (about a 3/4 of a second) squelch tail. This happens every time a mobile/portable unkeys. This issue didn't exists prior to the radio mods. The RX audio source seems to be the issue. The connection for this audio were taken from the pins array known as "J6" which is the pins that connect the logic board to the RF board. Pin 3 on J6 is the discriminator....from what I understand. The audio is great sounding and is passing the tone to the control tone panel but for some reason I'm getting this squelch tail each time the repeater is used.

I've check the squelch settings in the radio and confirmed the setting on the TP-154 tone panel.

Anybody have any idea why this squelch burst happens each time a carrier drops?

Thanks guys,
C
 

ramal121

Lots and lots of watts
Joined
Dec 5, 2008
Messages
1,742
Location
Sonoma, CA
In your previous repeater set-up you used handset audio which is filtered and mute gated. The maxtrac responds to reverse burst for tone PL or a turn off code for DPL. These are sent by the transmitting radio just prior to transmitter shutting down. When the receiving radio sees this, it will clamp the audio off before the transmitter quits and eliminate any objectionable noise burst. This is why using handset audio sounded clean.

Now that you are using discriminator audio there is no muting that is applied to it inside the Maxtrac. You are relying on the controller to take care of this and the way it is set up it's not so quick on the draw.

Since the Maxtrac will now not be responding to PL/DPL (the controller will) there will be no reverse burst advantage of an early drop on the audio mute line. This will allow at least a little blip of noise through.

What bugs me is the stated 3/4 second of noise on unkey. This sounds like "or" squelch to me. If a PL (or DPL) decoder looses its signal without benefit of a reverse burst or turnoff code, it will skate for some time before it decides the transmission just went away. This is for marginal signals and fade to keep the repeater from chopping.

I really doubt the CSI controller detects a reverse burst or turnoff code. You are then relying on the COR to signal the controller to mute as soon as it can. Make sure your COR adjustment is correct in the controller. You could try this real quick, remove the COR line from the controller and see if it still repeats. If it does you need to find out why the controller is not responding to it.

Where are you getting COR from now? Same place? I would probe the COR line, preferably with a scope, to see if it indeed drops exactly with carrier and does it fall off instantly or just kinda ramp its voltage gradually.
 

ronenp

Member
Joined
May 8, 2002
Messages
515
I didnt undwesstand exectly how you routr thr audio (if a block diagram of the audio path was added it would help) however if i understand correct and you take the audio from a discriminator then the audio is unmuted when no carrier present so something must mute this audio when no carreier present if it is the PL decoder that mute it then it might be that the time takes to the decoder to mute is that time
Useually a COR susyem is much quicker in muting so in standart repeater the mute system is a combination of the PL and the COR together by that the repeater must have PL and a carrier to keyd up and when the mobike finished the COR closes quicker then the PL and therefore the squelsh tail is much shorter .....

Hope my description was clear and that it is one of the reasons that might be at your site
Ronen - 4Z4ZQ
Ronen Pinchooks (4Z4ZQ) WebSite
 

eportel6607

Member
Joined
Jan 1, 2012
Messages
112
Location
South County, Rhode Island
Thanks guys for the detailed reply.
I'll check the COR line and see if the controller still repeats with it disconnected.
Ok now to answer your question regarding "Where are you getting COR from now?"
The COR signal is coming from the "RX Mute" signal in the radio. This output is normally active high (+5volts) and floats with no RXer activity. HOWEVER I had a link radio connected to these repeaters. I wanted to have the link radio transmit when the repeater detected a carrier...so I THOUGHT that if I inverted the COR signal from active hight to active low I could tie the PTT of the link radio to the repeater's receiver radio's COR line (on the making the connection at the "COR" terminal on the back of the TP-154) but this didn't work because the PTT line on a Maxtrac/Radios needs to be a ground potential not "active low"...so I took a pull down resistor and transistor and made the COR go to ground instead of "active low". The controller appears to have no problem with this and RXer activity will key the link transmitter directly. Prior to this mod I used an active high COR coming directly off the "RX mute" circuit Maxtrac.

The audio line comes off "J6" pin three and is jumped internally to mic pin 1. I made about 15 CAT5 cables with RJ45 plugs on them; all exactly the same wired in the same configuration as a standard Ethernet network cable (encase I need to replace a cable in the field I can use a standard network cable). This CAT 5 cable is then routed to the rear of the TP-154 controller.

I'll check the COR line...and might actually set one of the controller to detect an active high COR and disable the current "active ground" COR line that I'm using now to see what happens. At least I know for sure that this method worked prior to this mod. I was only using this method because I wanted the link radio to mimic and follow the receiver activity. I might need to take a different approach to this.

Thank you both for your time and input. The explanation of what is happening makes total sense to me.
I'll check out and let you know; likely today.
Thanks again,
Chris
 

cmdrwill

Member
Joined
Mar 30, 2005
Messages
3,769
Location
So Cali
All our TP-154's had two inputs, one discr audio for the decode section in the tone panel and muted/filtered audio for the 'repeat audio'. Then you get the muting of the noise when there is no signal in the receiver. And the muted/filtered audio is passed to the transmitter thru the TP-154.

The Maxtrac has a much faster squelch and PL decoder than the TP-154 does.
 

cmdrwill

Member
Joined
Mar 30, 2005
Messages
3,769
Location
So Cali
SQUELCH TAIL LENGTH *000#20#mm# *000#20*
mm 00-99 (0-99 Ms - 1 Ms/step) [mm = 0 = 0 Milliseconds]
Set to 0 for minimum tail. Only used if the receiver has a poor
squelch and can stop word clipping by adding squelch delay. If
there is a tail noise when set to 0, it is caused by slow
squelch response in the receiver. The TP-154 does not add any
more tail than is inherent to the receivers squelch if set to 0.

CARRIER DROP DELAY *000#45#mm# *000#45*
mm = 00-99, (0 - .99 Sec's 10 Ms./step) [mm = 99 = .99 Sec's]
Adjusts how long carrier remains on after CTCSS/DCS drops at end
of hangtime. Keeping the carrier on quiets the mobile while the
mobile CTCSS/DCS decoder is dropping and allows the repeater to
go off without a squelch tail heard. The default value is .99
seconds and probably will not need to be changed.
Note: The carrier drop delay is additive to hangtime and in
effect increases the total beyond the value set for hangtime.

Is Jumper 1 set correctly? JP-1 De-emphasis strap. If you have connected to the
discriminator output, JP-1 should be installed. If you have
connected to a source of flat (already de-emphasized) audio
such as the high end of the volume control JP-1 must be
removed. If JP-1 is improperly strapped the audio will not
sound proper

Added a separate input for RX Audio. Remove one end of C 12 and add RX AUDIO line from receiver.

http://www.connectsystems.com/products/manuals/TP154MAN.pdf
 

eportel6607

Member
Joined
Jan 1, 2012
Messages
112
Location
South County, Rhode Island
Cmdrwill,
Thanks very much for the information and the link to the manual. I tried to adjust both the squelch tail and carrier drop before I posted here on the forum. I found the issue. I found it because you guy made me very suspicious of the COR signal. If you recall I had inverted the COR signal from Active Hight to Ground....Not "active low"...but to ground potential. This is the most significant change that I made to the radio in regards to the receiver radio.
I took the Maxtrac that is being used for receiving and I removed the inversion transistor and pull up resistor. I then took the signal wire and wired directly to the “rx mute” point in the radio. This wire brings this signal to mic pin 2. Which of course is wired to the controllers “rx cos” terminal. I then swapped the jumper (J10) from – to + (active high) and the problem went away. It turns out that having the COR going to ground formed some sort of capacitance which held the COR open after the carrier dropped.
To test this initially (before I rewire the radio's COS) I put an multimeter on continuity and noticed right away that the cor was in fact lagging being after the carrier dropped.
Thanks guys. I'm not sure I would have went in this direction if it wasn't for you guys.
Thanks again. It looks like I'll be rewiring a bunch of Maxtrac for active high COR.
 

ramal121

Lots and lots of watts
Joined
Dec 5, 2008
Messages
1,742
Location
Sonoma, CA
Kinda thought it was slow response on the COR, glad you found it. That and the slowness of the PL decoder, well it was in no hurry to clamp the audio.

Now about the RX Mute line (or PA mute line). If you want an indication of both COR and PL this is the line to go to on the 5 pin logic board. However you found it floats when inactive, high when active and that makes it a little harder to work with. It controls a transistor in the 5 pin logic board that actually goes to ground active and is pulled to 5v by a 47k when inactive.I think the collector would be a better place to pick off the logic. In the 16 pin board, RX mute runs a pass FET in the audio line and is worthless to pick off logic.

Now since you will not need PL detect with the CSI controller only Carrier detect, there is a real COR line also in the radio. It comes from the RF board on P6 pin 2 labeled "squelch O/P". It is active high but if you follow it out to transistor Q805, it will give you ground active and 5v inactive on the collector. The only thing it does is to signal carrier to the uP. I'm sure adding a couple more things on this line won't upset it too badly. In fact, if memory serves me, there is a feedthrough or land on the PCB labeled "COR" and this is where it originates from.
 
Last edited:

eportel6607

Member
Joined
Jan 1, 2012
Messages
112
Location
South County, Rhode Island
Ramal,
Thanks! Great information. Well I would rather the COR signal be low. I'll look at doing this. I have forteen radios to mod. For repeater use I have a real problem using a full featured 16 pin logic board, 16-32 channel radio just to use as a RXer or TXer for a repeater so I usually stick to the 2 channel radios because they are much cheaper and I don't feel like I'm wasting a multi channel radio w/ signaling for this purpose. Of course it's harder to work with because nearly no signals exit the radio that I need...but I figured it I get enough of these radios and modify all of them at the same time and have all the controlller set up the same I doubt I'll have to do this again. The other thing is that every Maxtrac has been modifed so it could function as either a RXer or TXer. The modes are the same on all of them...just encase I have a bad TX at a site I can swap the radios, the antenna feedlines and the contol cables and I'm back in business.
Thanks for your input. I've documented everything that you mentioned and I'll look into that method in the very near future.

Thanks again.
chris
 

cmdrwill

Member
Joined
Mar 30, 2005
Messages
3,769
Location
So Cali
The COS input on the TP-154 have both Active high and low settings.

RX COS: Connect to a point that has good voltage swing when
the squelch is opened/closed. The best point to
connect is to the collector of the transistor that
controls the busy light (if the receiver has one).
Otherwise, you may connect to the squelch gate
control voltage. Your last choice would be to connect
to output of the noise rectifier.
If the point selected goes more positive (voltage
increases) when a signal is received, strap JP-10
center to the + side. If the point goes to a lower
voltage, strap JP-10 from center to the - side.
When the COS threshold control P4 has been properly
adjusted (see page 5), and JP-10 properly strapped
(see page 6), the front panel RECEIVE LED will
illuminate only when a signal is received. This
condition must be achieved for proper operation of
the interconnect.
NOTE: The squelch control in the receiver must be set
for quiet (squelched) receive. Set the squelch as you
would any squelch, but remember if you set it too
tight receive sensitivity may suffer.
 

eportel6607

Member
Joined
Jan 1, 2012
Messages
112
Location
South County, Rhode Island
cmdrwill,
Thanks for the info. I have since studied the pdf manual of the TP-154. Everthing is working correctly now. These radios are old. I think they all could use a realignment. It seems two have no receive at all. I'm hoping it's a IF RXer crystal issue...but I'm not sure yet.
Thanks again for your insight and help with this problem.
Chris
 
Status
Not open for further replies.
Top