VISAR- re-alignment needed after changing TX PWR level?

[borisf]

Hi!

When I change the TX power level of a Visar to the maximum value of 127, will I have to re-tune it afterwards or can I just change the value and everything is fine?


Thanks!

[nmfire10]

You can't just push the slider up to 127 and say "now i have maximum power". Put the slider back where it was before the radio goes up in smoke. Then try again when you actually have a wattmeter or service monitor attached to do it properly. Chances are it could use a complete alignment regardless for what its worth.

[borisf]

Sadly I can't put the slider back where it was. (because I didn't touch it yet.)

[Wowbagger]

This is somewhat tangential to the discussion, but...

These "I has tooner softs, n I wanna turn da dial to 11zezes 2 mak MORE POWER <grunt grunt grunt>" types remind me of my previous job. We were designing a very complicated mechanical monstrosity to handle surface mounted components for testing. The equipment had a calibration table to set various calibration parameters of the machine: the number of motor steps from home sensor to "in position to drop", motor acceleration parameters, time delays for vacuum systems - all of which varied from machine to machine (if they DIDN'T vary we wouldn't have needed to make them VARIABLE, now would we?)

We had this one customer, who had this one "engineer". He was pissed that he didn't get to design and build this project, and IMHO was always trying to sabotage the project. The equipment would be delivered to the company, uncrated, and set up by our technician, whereupon it would run as designed. This "engineer" would then immediately go to the calibration screen (which he INSISTED upon having access to) and would enter what he felt were the "correct" values.

It should be needless to say the equipment ran like 5h!7 after that - if it ran at all.

This "engineer" would then depart, saying "See! it's crap! I should have been the one to design this!".

Then the operators would hit the "Restore factory settings" button we added, recalling the backup values (gosh, why do you think we had to add that little feature?) and the equipment would once again operate correctly.

This "engineer" was also in the habit of opening the equipment and rewiring it to his satisfaction - replacing much of our control circuitry with his own crap which watched what our stuff did, then did what HE felt it should do. As a result, when we would release new firmware which did things differently (in order to speed things up), his stuff would break - and he would :o to his bosses that *WE* broke his stuff.

Due to his hamfisted work, one time the machine broke itself - doing over 30 thousand dollars of damage to itself. He raised holy hell that the machine was able to do this. I did the analysis and said "There's no way this could have happened - this sensor would have detected that condition and prevented the machine from doing that." "That sensor? Oh, I disconnected it - it didn't seem to do anything, and the machine worked without it."

(these stories are part of why I left that company - the management wouldn't stand up to this customer and tell them to get this pinhead off the project).

The point of my telling this story in this context is to try to help all you "tweakers" who think that they can just shove all the knobs to 11 to understand why this is a bad idea.

[tvsjr]

Go ahead and crank it up to 11... er, 127. Use it frequently. You'll cease being an issue when you let the magic smoke out of the PA.

[borisf]

Thanks for your advice!

[nmfire10]

I'll give a more complete answer now.

Yes you can adjust the power without requiring a complete re-tuning of the radio. All other settings will remain un-effected. However, you can not just arbitrarily crank the power slider up blindly. There are different sliders for different frequency ranges. You need to have a watt meter or a service monitor to do it. You adjust each one until the power is at the specified value. (Usually something like 4 watts for UHF and 5 watts for VHF). There is also an identical procedure for the specified low power setting which is probably something like 1 watt.

You can NOT just pick a frequency range and blindly move the slider and you also can NOT just crank it up above the specified value to have MORE POWER.