MTR2000 VSWR limit

WKRP · Post by **WKRP** » Thu Sep 08, 2005 9:59 am

The MTR2000 has a VSWR limit (I believe as low as 1.3:1 for some models). If the station is keyed and the limit is reached the station will stop transmitting. You must unkey the station then rekey to transmit again. I realize that ultimately correcting the high VSWR would solve this problem but, does anyone know of a method to change (increase) the VRSW limit, or have the station ignore it so as not to shutdown.

Thank you.

Will · Post by **Will** » Thu Sep 08, 2005 2:19 pm

NO, you will need to correct the bad antenna and/or feadline that is causing the high standing wave ratio, SWR, first.

The MTR is just trying to protect it's RF power amplifier from serious dammage due to the mismatch.

What kind of antenna, feedline, ect; do you have?

WKRP · Post by **WKRP** » Fri Sep 09, 2005 7:41 am

Thanks for the reply.

Not what I was hoping for but at least you answered my question.

We've employed this radio in several different sites with different antenna systems, so I really don't have any specific info in front of me.

Post by **HumHead** » Fri Sep 09, 2005 9:43 am

You could also install an isolator (and accompanying harmonic filter) on the output of the transmitter. Reflected power from the antenna would be sent to the isolator's dummy load instead of being reflected back to the MTR2000.

WKRP · Post by **WKRP** » Fri Sep 09, 2005 11:52 am

Yes, this is probably the approach we'll take.

Thanks.

n1pfc · Post by **n1pfc** » Sat Sep 10, 2005 9:27 am

HumHead wrote:You could also install an isolator (and accompanying harmonic filter) on the output of the transmitter. Reflected power from the antenna would be sent to the isolator's dummy load instead of being reflected back to the MTR2000.

The MTR2k already has as an isolator in it... depending on what PA you have you could even have more than one. The 100W versions have a single stage and the 30-40W ones have a dual stage one at least in UHF which are the ones I usually deal with.

The real solution is to fix the antenna / duplexer problems.

Kurt

Nand · Post by **Nand** » Sat Sep 10, 2005 4:35 pm

Adding another one hides the fact from the MTR that there is a problem. It better has a large dummy load on the circulator. The internal circulator load is likely where they measure the reflected power that triggers a shutdown.

Nand.

n1pfc · Post by **n1pfc** » Sat Sep 10, 2005 5:56 pm

Nand wrote:Adding another one hides the fact from the MTR that there is a problem. It better has a large dummy load on the circulator. The internal circulator load is likely where they measure the reflected power that triggers a shutdown.

Nand.

I'm sure that's how they do it. It's that way on the MSF5000's and on a couple of GE amplifiers that I have. But again, it doesn't solve the real problem, only hides it from the MTR.

Kurt