Batboard

Recently the UN has been told that we have to move our operating fcys out of the 150-160 band and go down to 138-150. I know that we have to change duplexer, antennas etc. even the power amp is out of band, what about the Rx. Now as far as the HTs and the mobiles go, will there be some degradation in the Rx Tx. Your input is appreciated please. This will be a big project, sinc I have 18 repeaters and over 1000 mobiles and HTs.
132-174mhz radios

MITYTONE wrote:Recently the UN has been told that we have to move our operating fcys out of the 150-160 band and go down to 138-150. I know that we have to change duplexer, antennas etc. even the power amp is out of band, what about the Rx. Now as far as the HTs and the mobiles go, will there be some degradation in the Rx Tx. Your input is appreciated please. This will be a big project, sinc I have 18 repeaters and over 1000 mobiles and HTs.
132-174mhz radios

You don't mention make or model of the field radios, but any Motorola radio spec'd to work the full 132-174MHz band performs to spec across the entire band. I can't really speak for other manufacturers. The receiver in the MTR2000 covers the full band, so no worries there.

Todd

I would agree - if the mobiles and portables you have cover the necessary frequency range - the performance should not suffer. You may need to replace antennas for optimum performance.

As far as your duplexers, what is necessary will depend on what units you have. I would contact the duplexer manufacturer and give them the model number of the units you now have, your current operating frequencies, and your new frequencies. They can advise if the units will tune down or can be modified with new cables and possibly coupling loops.

Hams face the same issue moving commercial range duplexers to 2 meters so there is much information on the subject on the repeaterbuilder web site.

Thanks guys. The duplexer and antennas will have to be replaced also the power amplifier.
Duplexer info: Model TYD4031 (130-146mhz )
Model TYD4032 (144-160mhz )
Model TYD4033 (158-174Mhz)
The PA Model : CLN1224 (132-154Mhz )
Model : CLN1225 (150-174Mhz)
Thanks once again.

Duplexer info: Model TYD4031 (130-146mhz )
Model TYD4032 (144-160mhz )
Model TYD4033 (158-174Mhz)
The PA Model : CLN1224 (132-154Mhz )
Model : CLN1225 (150-174Mhz)

From what I see here, you will have to refit your cans for operation in the lower band, and at the very least, invest in new 1/4 wave cables, coupling loops and a complete retune.

The high band cans(158-174 will definitely need to be replaced if retuning with cables and loops will not get you the necessary isolation.

The amps will need to be replaced as a retune would be more than the cost of a new in-band assy.

Of course, the antennas will probably no longer work correctly down that far either, but if your 144-160 antennas are in good shape(taken apart and joints inspected), then you could probably get away with the tin foil tuning method to bring the antennas down in frequency.
This is a bare bones method of applying several strips of aluminum foil along the length of the radome, and checking reflected power as you 'tune'.
(It's really not for long term use, but will work in a pinch while the proper antennas are on order and awaiting delivery).
The above is for use only on fiberglas radome collinears...
If you try the tin foil tuning method, you should elevate the antenna at a minimum of 6 feet above ground, to minimize ground reflections so your tuning will be more accurate, but regardless, you should still be well within a usable range if not.

Sell the now out of band amps, and purchase new so you get a good Mfr's warranty and use the proceeds from the sale of the amps to down grade your overall costs on infrastructure.

BTW, what power output are these amps, and what imput power is specified and at what supply voltage?
I am notably curious here...*thanks*

Duty cycle?
Cooling provided by..?

Replacement coupling loops run the range from $40.00/Pr. to a few hundred....BpBr type, Notch(with cap)....YMMV of course.
TX-RX makes fine coupling loops for their cans.

You'll be replacing the PA's in the MTR stations if you have to go below 150.0. They wont tune down there. You'll need the 132-154 FRU.