2 pill amplifiers...

[eagleeyes]

And by the way. If anybody thinks im gonna drive the snot out of anything it would be my nose. Not going to do that to any equipment. Its a waste of money to beat the crap out of it.

 

[AudioShockwav]

Do not sweat it eagle, you look to be on the right track.
Many people do NOT like dual final export radios for many reasons, and prefer to run single final, single band radios like the Cobras.
Just like many amps say hi-drive on the front, they are not, even the Texas star amps that are HD or hi drive need to be treated with kid gloves.
I have seen some stupid stuff over the years.
Guys that take a Mod V and put it in front of a 500.
But they will argue, " a 667 is just a 500 with a mod v built in "
A 667 is a 500 with a 2290 ( now fet`s) driving it with a ton of unnecessary padding built into the input of the 4-2879`s, they run hot as hell and eat up unnecessary current for what they deliver.
They were first built long ago for old single final radios that struggled to make 5 or 6 watts even tuned up.
A mod v is not even push/pull because there is only 1 transistor in them, they are dirty by nature.
Then there are the guys that put the mod V in front of a 667........


73
Jeff

 

[Crusher]

Lol, that's as bad as the guy I know that used 8 1446's to drive 8 2879's. LOL. Or the 2 x 2 amps that were around. Meaning 2 1446's driving 2 x 2879's. Someone's always coming up with a gimmick or a new idea to make money.

 

[eagleeyes]

Is it bad to drive a amp like at 10 -25% of its range or is it best to drive it at 25% of its power all the time?

 

[eagleeyes]

Ive got another question. Am I tuning the antenna to the amp or just to the radio then add the amp in?

 

[tba02]

Tune to the radio and then check your numbers with the amped powered up to make sure you are in a safe range.

 

[eagleeyes]

Tune to the radio and then check your numbers with the amped powered up to make sure you are in a safe range.

with it amper up I get 1.5 thats having the meter hooked after the amp. The radio reads that its fine

 

[tba02]

Radio -> Amp -> Meter -> Antenna = 1.5:1 w/ power applied?
If so, you should be fine.

 

[eagleeyes]

Radio -> Amp -> Meter -> Antenna = 1.5:1 w/ power applied?
If so, you should be fine.

Yup in that order with power applied. Thanks for the quick reply. What is a ok range for swr and what is bad range? With amp installed.

 

[eagleeyes]

I know you want to get close to 1:1

 

[tba02]

What is a ok range for swr and what is bad range? With amp installed.

Generally speaking, I wouldn't want anything higher than 1.8:1 and even then I would lower output to bring it down. I generally shoot for 1.3:1 if possible but with certain amps it just won't happen unless you tweak the amp circuitry. People smarter than me say you can live with 2.0:1.

Loss Chart
http://www.firestik.com/Tech_Docs/SWRLOSS.htm

 

[eagleeyes]

Thanks very much for the reply. That chart was very informative. Saved it to my bookmarts. Much appreciated

 

[tba02]

It took me a minute to locate - more reading material about SWR which provides a much better picture.
http://www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf

 

[eagleeyes]

Awesome. Great material will definitely read

 

[AudioShockwav]

Generally speaking you want to stay under 2.0:1 VSWR.
The harder you drive the amp the more critical this becomes.
Often you will see builders of CB style amps tell you that you must have 1.5:1 VSWR or lower because to achive the numbers they say there amps will do they are driven hard and/or at voltage higher than 13.8.
When you start running at 16-17-18+ volts things can go bad fast.
I have run my DX 500 into swr of higher than 2.0:1 plenty of times with no ill effects working both 10 and 12 meters because I did not want to stop, get out and switch antennas, but I only run that amp at about 320/350 watts (peak) out on SSB at normal mobile voltage levels.
Even on AM I limit carrier levels to 100 watts max.

73
Jeff