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Vertex VRX-7000 transmit issue


chasedog1

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5 hours ago, chasedog1 said:

A Vertex tech sold me the repeater after he serviced and did an alignment. everything seems to be back correctly. The HT only receives on the frequency the repeater is on, I go a few mhz up or down and its gone. it does stop when I remove the HT's antenna

I don’t think anything is wrong. You shouldn’t expect a handheld radio not to have its receiver circuitry overwhelmed by a high power transmitter nearby. 

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The repeater is constantly generating low power RF with PL by design.  The final PA is turned on and off to facilitate actual transmit. 

You are picking up that RF signal and it's opening up your radio.  This is completely NORMAL and is not a concern.

MTR and Quantar repeaters do the same thing. 

 

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2 hours ago, tweiss3 said:

This may be the case, I have no personal experience with this specific repeater, but when my Kenwood was on the bench, the second it flipped into service mode, and the oscillator was turned on, all radios on that frequency in the room picked up the carrier, even without the PA being on.

Yeah, I have had several of these that I have worked on.  Kenwood turns off the oscillator when they are not keyed.  Motorola, Vertex and some others just turn the PA on and off.  It allows for a quicker keyup time if the oscillator is already running on frequency.  Now that delay isn't typically very long, but with trunking radio systems it can have an effect.  The other thing is if it is still locking on frequency when the PA turns on there can be an audible tone heard on the air as the frequency stabilizes which can effect the signaling the transmitter puts out to the subscriber radio letting it know it's on the channel and transmitting.  That stuff happens pretty quick but any delay is still a delay that the user can see and complain about.  ANd if it effects the outbound signaling word on the trunking system, the call can be lost by the subscriber.

 

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4 hours ago, chasedog1 said:

Yes the tones are used on Rx and Tx. When i have the HT I can go to the other end of the house and it stops receiving the signal but another HT in the same room still receives it...

Same make, or different? Same antenna?

If different, you may just have run into a difference in receive sensitivity. (A Retevis cheapy [2 free with RT97 package] is 0.25uV, BTech unit shows 0.2uV -- for comparison, a Kenwood D74 in the Amateur bands is 0.18uV).

 

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15 hours ago, chasedog1 said:

I have the repeater setup and when I turn on a HT the repeater seems to be dead keying or transmitting but I am not doing anything. It does it on all channels all the time. I can key the HT and hear myself then key the mic on the repeater and hear my self with the HT.. any ideas ?

Help me understand the proximities involved and the exact nature of your concern.  When you’re in the same room as the repeater with one of your handhelds, no matter what channel you tune the handheld to you hear whatever the repeater transmits.

Also, using an identical handheld, when you go farther away from the repeater the handheld only hears the repeater on the correct channel.

Is that a correct description?

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I go farther away from the repeater and the signal drops off to nothing unless I ask someone to key it. This happens on all channels no matter what. It happens in repeat or base mode as if there is a leak powering the xmitter with very low power. I am going to try to obtain a signal field strength meter and take more readings.

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6 minutes ago, chasedog1 said:

I go farther away from the repeater and the signal drops off to nothing unless I ask someone to key it. This happens on all channels no matter what. It happens in repeat or base mode as if there is a leak powering the xmitter with very low power. I am going to try to obtain a signal field strength meter and take more readings.

Is there a transmit LED or display on the repeater (or even a wattmeter on the output) that indicates when the transmitter is transmitting?

Does it stop if you power down the repeater?  (I know that probably sounds like a dumb question and maybe it is. )

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There is no meter on it  or indicator led. If I turn the repeater off the phantom signal will stop. I am not keying the repeater up with anything and it still has a tiny signal output but nothing can be heard  audio wise on the HT's. I am going to and try to make a video clip of the issue by starting in my office and walking to the other side of the house where the signal stops. This a 40+ watt tx normally so if it were even on low I would have a signal at the other side of the house if the key was pressed. I will be back with a clip or a link to view the phantomness happening here...

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Remove the antenna on your handheld. Does it still happen?  

Is the case correctly assembled to the repeater? What about the duplexer?  Cables?

I suspect your handheld is just not very good at rejecting interference from the repeater. Typically you’d never use a handheld in the same room as a repeater. 

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23 hours ago, WRKC935 said:

The repeater is constantly generating low power RF with PL by design.  The final PA is turned on and off to facilitate actual transmit. 

You are picking up that RF signal and it's opening up your radio.  This is completely NORMAL and is not a concern.

MTR and Quantar repeaters do the same thing. 

 

Obviously you missed this since we are still discussing it. 

It's NORMAL.  That's the way the Vertex works.  And Vertex isn't the only repeater that does this. 

Some others strip the PL.

MTR's and Quantars have a programmable REST frequency they revert to when they are receiving so this doesn't happen in situations were the repeater is located close to where portable radios are going to be.  But again.  This is normal and expected.

Look in the programming and see if there is a setting for a REST frequency.  If there is it's probably set to the TX frequency of the repeater.  Change it to something else but DO NOT set it for the receive frequency or it will interfere with the receiver of the repeater.  Once the issue goes away, program a radio up for to receive the rest frequency and you will find that it will hear the repeater generating a signal on the rest frequency.  And when you key the repeater, the signal will go away.

Or you can continue to connect and disconnect your antenna's, walk around the house and see where you can hear the signal.  Ask more questions and get told more nonsense about what is NOT causing it and continue to wonder what it is.  Even though I have told you.  And since I believe I am the only one on here that does this shit for a living.  I just might know what the hell I am talking about.  Maybe...  But at this point, it's anybodies guess.

 

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2 hours ago, WRKC935 said:

Obviously you missed this since we are still discussing it. 

It's NORMAL.  That's the way the Vertex works.  And Vertex isn't the only repeater that does this. 

Some others strip the PL.

MTR's and Quantars have a programmable REST frequency they revert to when they are receiving so this doesn't happen in situations were the repeater is located close to where portable radios are going to be.  But again.  This is normal and expected.

Look in the programming and see if there is a setting for a REST frequency.  If there is it's probably set to the TX frequency of the repeater.  Change it to something else but DO NOT set it for the receive frequency or it will interfere with the receiver of the repeater.  Once the issue goes away, program a radio up for to receive the rest frequency and you will find that it will hear the repeater generating a signal on the rest frequency.  And when you key the repeater, the signal will go away.

Or you can continue to connect and disconnect your antenna's, walk around the house and see where you can hear the signal.  Ask more questions and get told more nonsense about what is NOT causing it and continue to wonder what it is.  Even though I have told you.  And since I believe I am the only one on here that does this shit for a living.  I just might know what the hell I am talking about.  Maybe...  But at this point, it's anybodies guess.

 

Actually nobody but you is still discussing it. You’re the only one who has posted since Friday. Maybe you have the responses sorted in order of votes rather than order of date and time. I’ve done that before.

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3 hours ago, WRKC935 said:

Obviously you missed this since we are still discussing it. 

It's NORMAL.  That's the way the Vertex works.  And Vertex isn't the only repeater that does this. 

Some others strip the PL.

MTR's and Quantars have a programmable REST frequency they revert to when they are receiving so this doesn't happen in situations were the repeater is located close to where portable radios are going to be.  But again.  This is normal and expected.

Look in the programming and see if there is a setting for a REST frequency.  If there is it's probably set to the TX frequency of the repeater.  Change it to something else but DO NOT set it for the receive frequency or it will interfere with the receiver of the repeater.  Once the issue goes away, program a radio up for to receive the rest frequency and you will find that it will hear the repeater generating a signal on the rest frequency.  And when you key the repeater, the signal will go away.

Or you can continue to connect and disconnect your antenna's, walk around the house and see where you can hear the signal.  Ask more questions and get told more nonsense about what is NOT causing it and continue to wonder what it is.  Even though I have told you.  And since I believe I am the only one on here that does this shit for a living.  I just might know what the hell I am talking about.  Maybe...  But at this point, it's anybodies guess.

 

This may be the case, I have no personal experience with this specific repeater, but when my Kenwood was on the bench, the second it flipped into service mode, and the oscillator was turned on, all radios on that frequency in the room picked up the carrier, even without the PA being on.

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14 hours ago, WRKC935 said:

Yeah, I have had several of these that I have worked on.  Kenwood turns off the oscillator when they are not keyed.  Motorola, Vertex and some others just turn the PA on and off.  It allows for a quicker keyup time if the oscillator is already running on frequency.  Now that delay isn't typically very long, but with trunking radio systems it can have an effect.  The other thing is if it is still locking on frequency when the PA turns on there can be an audible tone heard on the air as the frequency stabilizes which can effect the signaling the transmitter puts out to the subscriber radio letting it know it's on the channel and transmitting.  That stuff happens pretty quick but any delay is still a delay that the user can see and complain about.  ANd if it effects the outbound signaling word on the trunking system, the call can be lost by the subscriber.

 

Makes sense to me. It appears that the Quantars have more shielding to them though. Probably why they can be stacked 10 high in a big system and not interfere with each other.

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