SGC SMARTPOWERCUBE SG-500 Specifications download pdf

ALC Adjustment Procedure

Alan Applegate (K0BG) on February 8, 2005

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ALC Adjustment Procedure:

Contrary to popular belief, modern HF amplifiers do not require a full 100 watts to drive them to full output. The truth is,

most tube amplifiers only need about 65 to 80 watts for full rated output, and some as little as 40 watts. Depending on

their input circuitry, some solid state designs require just 25 watts! Regardless of their design (tube or solid state), over

driving any amplifier produces a lot of negative results. Intermodulation distortion (IMD) is increased, tube (transistor) life

is shortened, power supplies are over stressed, and the resulting splatter is anger inducing.

With the exception of most solid state mobile amplifiers, almost every modern amplifier has an ALC output. ALC, which

stands for Automatic Level (Linearity) Control, provides an adjustable negative-going DC voltage which is fed back to the

transceiver to control the amount of drive to the amplifier. If it is connected, and properly adjusted, ALC can limit or

eliminate the aforementioned negatives. The problem is a lot amateurs never connect the ALC believing that the 100

watts PEP their transceiver delivers can't overdrive their amplifiers. This is an erroneous notion. Even when it is

connected, all too often it is not adjusted properly.

The proper level is easy to arrive at and requires just two pieces of test gear; a dummy load and a peak-reading

wattmeter. The dummy load is necessary for obvious reasons. The need for a peak reading wattmeter is less obvious.

Without getting into a deep technical discussion about power supply dynamics and other esoteric data, let's just say it is

best to adjust the ALC by transmitting via SSB while monitoring the PEP.

Before we start let's go over what we're going to do. We're going to set the ALC just at the level where the power out is

just below the point where the amplifier transverses into non linearity (the chart at right was made for a fictitious solid state

amplifier, but clearly shows the transverse point). Then we're going to increase the ALC slightly so we're well into the

linear portion of the amplifier's power curve. So here we go.

First, set the transceiver to put out its standard 100 watts PEP (into a dummy load). Your speech patterns are important

here, and rather than say "test, test", recite your address, city and state.

Next, tune up your amplifier like you normally do, but with the ALC disconnected. WATCH YOUR DRIVE LEVEL! 30 to 50

watts is typically enough for tune up purposes. When you're finished put the amp in standby.

Next, hook up the ALC and turn the amplifier's ALC adjustment pot fully on (usually clockwise). Turn on the amplifier and

transmit in SSB again with full drive. If the ALC is working as it should, the peak power out will be well below what it was

without the ALC connected. Slowly decrease the ALC level while continuing to talk. At some level, the peak output power

will stop increasing. The control should be turned back up until the power again drops. A good rule of thumb is 10% down

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Page 1 - ALC Adjustment Procedure

ALC Adjustment ProcedureAlan Applegate (K0BG) on February 8, 2005View comments about this article!ALC Adjustment Procedure:Contrary to popular belief,

Page 2

by WA1RNE on February 11, 2005 Mail this to a friend!K2WH, any idea what happened?? I was trying to create another post and my computer hung, but I do

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**But tranceiver ALC control characteristics are not standardized; each model hasits own unique gain and dynamic characteristics. (Internal ALC intran

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YOUR CREDIT CARD NUMBER HAS BEEN FOWARDED TO US. YOUWILL BE BILLED $800. NEW TUBES WILL BE "DROP SHIPED"TO YOU IN A JIFFY BAG,

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from the peak power out. This keeps the amplifier well within its linear curve. If you're not going to use any built in speechcompression, this i

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Bravesemo!This article should be COMPULSORY reading for hams getting their 1st Amp. Wayyyy too many hams fall into that oldcontester credo..."a

Page 7

by LNXAUTHOR on February 8, 2005 Mail this to a friend!- who uses ALC anyway?:-)- seriously, tks for the article...RE: ALC Adjustment Procedureby NO9E

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RE: ALC Adjustment Procedureby N6AJR on February 8, 2005 Mail this to a friend!Belive it or not I never use ALC. I set my amplifiers manually. I just

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AMRE: ALC Adjustment Procedureby WA2JJH on February 9, 2005 Mail this to a friend!notone-am, your system sounds very good to me. I may employ a simila

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This adjustment procedure is good, but even if it's followed to the letter, their is a "variable" that is very dificult to accountfor;I

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the biblical code and ther types of psuedocryptology!Be warned M&M lyrics played backwards and translatedto 1000 B.C. arameic are where it is at!!

Page 12 - TO YOU IN A JIFFY BAG

procedure in the PW1 manual, but is similar in concept to the method described here.I have my PW1 set as described in this article and run my exciter

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SGC SMARTPOWERCUBE SG-500 Specifications

Browse online or download Specifications for Television antennas SGC SMARTPOWERCUBE SG-500. SGC SMARTPOWERCUBE SG-500 Specifications [en] User Manual

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