Duplexer tuning

[WSBZ540]

My question isn't what your thinking...

So I know how to tune one but, for those with repeaters what kind of attenuation are you getting?

I put my repeater on the air, and the next day we had a pretty nasty storm. Repeater seemed to recieve but not transmit. Replaced the tx Saturday and thought all was good, but still no tx. Checked duplexer and I'm barely getting 1 watt out.

 

I have another repeater on standby, so I got it's duplexer out, and retuned it. I got it to -65, but a 5watt signal from around 7 miles away is all I can get without the tx blinding the rx. It's a fumei duplexer, same as the original. I just can't get good attenuation. I think I'm gonna need 80 or more.

 

Anyone have any numbers to work with?

[nokones]

My EMR Corp Duplexer is set at -87dB and works very well.  Most cheap Chinese Duplexers have plastic inserts in the cavity ports that easily burn out from normal RF use.  I would check the plastic inserts more than likely you will need to replace them.

How much RF power are you transmitting into the duplexer from the radio?

[WSBZ540]

1 hour ago, nokones said:

My EMR Corp Duplexer is set at -87dB and works very well.  Most cheap Chinese Duplexers have plastic inserts in the cavity ports that easily burn out from normal RF use.  I would check the plastic inserts more than likely you will need to replace them.

How much RF power are you transmitting into the duplexer from the radio?

50 watts. It's a new duplexer, just having more desensing on the rx than I wanted.. 

 

Retuned and did some really touching adjusting on it and got 80,85 attenuation. It's very slightly desensing the rx but I think it'll be OK. Anything <70 just isn't gonna cut it.

[nokones]

Are you using a specific repeater station or two KG1000G Plus mobiles as a repeater?

[WSBZ540]

Two mobiles, not kg1000s though. I have a controller for up to 8 radios, but Im presently using 3 radios for gmrs. Two makes the repeater pair, and a 3rd as an rf link to another repeater 40 miles away.

[WSBZ540]

I did a final tune on it using a dummy load on the antenna and the vna on the low/high ports. Seems to not have detectable desensing now.