MaxTrac excessive power out?

[airboss]

DM44MJA7JA5AK. Programmed the 440Mhz ham band just fine (using the "shift method"). Adjusted the RX and TX VCO's per repeater-builder.com/motorola/maxtrac/maxtrac-adjustments.html

It works great - but the power out is a whopping 90 watts. (About double it's advertised power).

Any thoughts?

thanks

Alan, W7EJT

[RFguy]

My first thought is to check your wattmeter. I have lots of these that I've used for paging and have never seen them past 60 watts full out (I set them full out briefly to check transmitter condition).

How much DC current are you drawing? This can be a clue to actual power.

[abbylind]

Ditto on checking your power supply to see current draw. I'd also look at the spectrum analyzer to see if you throwing spurs

[n7maq]

what is the output in it's factory band limits?

[airboss]

what is the output in it's factory band limits?

I have left channels 11 thru 32 as within the "factory band limits" and will check the power out there. Very good suggestion - thanks!

Regarding the other inputs - very good - I will check the current draw from the PS and try to calibrate the watt meter/swr meter.

Will report back tomorrow!

Thanks to all !!!

[Satelite]

Hello:
Think I recall a post way back about the pa doing wild and high wattage output when taken out of band on a maxtrac.
Bear in mind that you changed the rx and tx steering voltages but this doesn't change the pa specs as it was built to perform at 450 to 470 megs and not down into the ham band so it sorta changes the pa drivers circuit.
Thought I also saw that a modification with a trim pot to manually adjust the pa drivers circuit was the cure for this.
Don't recall where but think if you googled it youd find the mod on the internet or someone here might recall where it was.
The 90 watt you claim was on uhf but I read about it on a d43 vhf maxtrac.
Think it might have even been a long time back member now gone from the bd known as eklb that may have had this once and posted on it.
Might try searching wild wattage output here with EKLB as the author.
The posting doesn't mention the maxtrac pa driver mod but I remember it from somehere on this.
Google maxtrac pa mod and id bet youd find it.
Satelite

[Satelite]

Hello:
Just googled maxtrac pa mod and I easily found it on repeater builder with very good pics and info provided on how to do it.
Now I know why it stuck in my mind .
I too back in august 13th 2006 ran into a 80 watt out on a m100 which is similar to your problem and I posted on it.
Search here on batlabs for author satelite with M100 45w amp hates me !
Its got info that may help you .
Satelite

[airboss]

Satelite - great! I have lot's to do!

I'm retired, so plenty of time...

thanks again, to all you fellas...

[eleet]

Please don't hack up your firmware or logic board trying to fix this on a UHF radio.

Many of the 450-470 radios were not aligned for the 440-450 portion of the band. To align this part you must go into service/board replacement/logic board. This is usually all that is required and I can't think of any other legitimate case that would require a different action.

Every Maxtrac firmware I have ever looked at: masked logic board 2.00, limited firmware 4.00, usual expanded firmware 5.34 and 5.36, 99 channel firmware 5.35, radius firmware 20.00 and 21.01 -- should work fine for using 450-470 split radios down to 440. Same with GM300. They figured they would operate down to 440 from the conception. In the factory they save time with alignment by doing 12 tunings instead of 16.

[airboss]

How about a big "DUH"?

I'm using an old SWR/Wattmeter. I got to thinking about frequency. My meter is only good to 30MHz!!!!!!!!

Kinda hard to measure power and swr on a 440MHz machine with that!

That would be one reason it shows 90 watts out - Still, I'm going to do the PA Mod...

Sorry, for my ignorance...

[N4KVE]

Years ago I had several 450-470 Maxtracs that I used at 442 rx, & 447 tx. The tx was fine, & put out normal power, but the rx was a little deaf at 442. Not too bad, but not as good as the ham radios. But not bad enough to have to fiddle with anything. GARY