Batboard

I just picked up this amp via Ebay and have found that Motorola no longer stocks schematics or other doccumentation for it. It is a rack mounted style possibly used at one time with a repeater or base station.

I would like to use it on 2-Meters in the 144 - 147 range. If anyone has any experiance with this amp or documentation for it, I would like to hear from you.

Thanks,

Jack

That's a continuous-duty brick for a Micor base station/repeater. You'll need to find a Micor manual to get the docs.

My list shows that being a 162MHz split deck - you may have to do some work to move it to the ham bands?

tvsjr wrote:That's a continuous-duty brick for a Micor base station/repeater. You'll need to find a Micor manual to get the docs.

My list shows that being a 162MHz split deck - you may have to do some work to move it to the ham bands?

Thanks for your reply. I belive that I will power it up and check it out.
It would be nice if it's broadbanded enough to take care of my needs. But your probably correct about needing to retune it.

Jack

The 2 Range covers 150.8 MHz to 162 MHz and can be RF Driven with .75 ~ 1.0 Watts from a HT. Although it's out of range for the 2 meter amateur band this RF Power Amplifier should put out 75~90 Watts as it stands.

You'll need a +13.8V DC @ 25 ~ 30 Amp Power Supply when testing it out. On the RF Power Amplifier, you'll notice a sticker indicating a terminal indicating Keyed A - so with a Jumper clip wire that point to the Negative terminal of the Large BLACK terminal strip.

I should've mentioned the power supply requirements... lots of good, clean power will be important. And, of course, an adequately sized dummy load. Fortunately, Dan's an expert.

Once you get it running it should run *forever*. Tweaking the transistor biasing, if possible on those bricks, will give you more efficiency and less heat.

Dan562 wrote:The 2 Range covers 150.8 MHz to 162 MHz and can be RF Driven with .75 ~ 1.0 Watts from a HT. Although it's out of range for the 2 meter amateur band this RF Power Amplifier should put out 75~90 Watts as it stands.

You'll need a +13.8V DC @ 25 ~ 30 Amp Power Supply when testing it out. On the RF Power Amplifier, you'll notice a sticker indicating a terminal indicating Keyed A - so with a Jumper clip wire that point to the Negative terminal of the Large BLACK terminal strip.

Thanks for your reply Dan. I was aware of the likely need for 20 amps or more for the P.S. Unfourtunately, I am not finding exactly what you described on this particular amp. It does have a small schematic on the back that points out the five pins on the end of the amp. These are on the same end as the BNC RF input. Four of them are in line with the A+ A- black terminals. There is a fifth one that is I.D. as the "SWA". The cluster of the other four pins are I.D. as "+ - Meter".

I am wondering if the pin that is I.D. as SWA might be what you were thinking of? I can send you a JPG if it would be helpful.


Jack

hello i have one also and i noticed when inline between an ht and antenna the rx signal is reduced ... there is no pre-ampon it .
that amp was for a micor repeater tobe used w/ a seperate reciever.

otto

The SWitched A- or just SWA is the Pin you must connect back to the Negative connection on the large terminal strip. Also there's two Tunable capacitors that I would not touch till you've got some RF Output. These are used as inter-stage coupling between the RF (PNP) transistor stages. If initially you got roughly 40~60 W Output, then take a well insulated Tuning Tool because there's DC voltage on those capacitors and slowly adjusting each variable capacitor for maximum Power Output on a Bird Wattmeter with a 100-250 MHz 250 W Slug. Use a Good known 50 OHM 100 to 250 Watt RF Dummy Load.

The RF Transistors line up in this fashion:

/\/\9622 or 11L31 QTY 1 Control Driver

/\/\9623 or 11L32 QTY 1 Driver

/\/\9624 or 11L33 QTY 2 Pre-Drivers

/\/\9625 or 11L34 QTY 4 Finals

Incidently the Final PNP Transistors are No Longer Available through MOTOROLA! It's a long story of /\/\'s stupidity in their A.A.D. National Parts Department Material Purchasing Group. Another time, another Post.

"IF" you should need to replace the RF Finals or need to keep spares in the Junk Box, then I'd suggest going to the Dayton Hamvention or local Hamfests and looking for the VHF High Band Micor RF Power Amplifier boards with the RF devices still mounted on them.

NOTE: This is very important, “IF” you have a quantity of 4 11L33 mounted as the Final transistors, your amplifier was serviced by the /\/\ Infrastructure Depot and they modified the amplifier for a maximum of 100 Watts because of the RF rating on these transistor devices. Do not attempt to increase the RF Power Output or I’ll guarantee you’ll blow the 4 devices.

On the upper right hand side of this PA there's a Potentiometer for setting the RF Output and inside there's a RF Sensing circuit for High Reflected VSWR, which automatically reduces the Power Output depending on the mismatch.

There’s also a modification that can be made to allow the RF amplifier a High / Low Power Output option for Primary Power 121V AC / Battery Back-Up +13.8V DC to extend the use of the Base Station / Repeater time during a Primary Power Failure. This might be available on the “Repeater-Builders. Com website”.

For the Amateur Radio Operators out in this big wide world, these /\/\ RF Commercial Duty MICOR Base Station Amplifiers have never included Coaxial T/R Relays or Receiver Pre-Amplifiers in the Design or Development of the units. These were Developed for the VHF Commercial Business Band users.

Dan