ALC not work fine see a video

iz7auh

Hello I have problem with ALC with my amplifier, please looking a video explain the problem.

https://www.youtube.com/watch?v=ThB_RySDQJ0

John W9KXQ

Frank,
I have the Expert 2K-FA amp, and the input drive should be no more than 40 watts.  You video shows you driving it with 100 watts.  I am not sure of the input specs on the 1.3K but when you reduced the drive, looks like it cleared the problem. 
John
W9KXQ

Doug Hall

Frank,
Please refer to the Flex hardware reference manual regarding ALC:

"Please note this input is provided as a safety measure for external amplifiers. It is NOT meant to be used in regular operation as an active power control input or to modify the “attack” of an external amplifier."

So I do not believe that the ALC implemented in the Flex-6000 radios will do what you want.

John W9KXQ

Doug & Frank,
I don't use the ALC, and as you pointed out Doug i doesn't do for operation.  The ExpertAmp does not need the ALC if you control the Drive.  I use DDUtil and set the Auto Drive per band.

John
W9KXQ

Doug Hall

John,
Agreed - I think DDUtil and AutoDrive is the best solution for amplifiers that require far less than 100w to develop maximum output.

That's one advantage of the older amps like the Heath SB-220, Drake L-4B, Drake L7, Ten Tec Centurion, Henry 2K, etc. - basically any amplifier that uses a pair of 3-500Z triodes in grounded grid. When properly tuned they can't be overdriven at 100w. They're instant-on and very tolerant of user error, but you lose the advantage of being able to change bands instantly.

73,
Doug

KY6LA_Howard

Instant ON after the. filaments take time to warm up

Doug Hall

Which, on a 3-500Z, is less than one second. That's more instant ON than most microprocessor-controlled solid state amps. My Quadra took a few seconds to boot up. I don't know how long the Expert Amps take, but my guess is that it is longer than 1 second.

Lee - N2LEE

Frank, Using ALC operates exactly the same as turning down your power manually. The only difference is the amp provides feedback to electronically control the output power of your transmitter. Most solid state amp manufacturers recommend using ALC. (including SPE)

If ALC is setup correctly you will get maximum power from the amp.

The settings you have are exactly as SPE recommends...
Using ALC operates exactly the same as turning down your power manually. The only difference is the amp provides feedback to electronically control the output power of your transmitter.

SPE recommends running your transmitter at full output and let the amp turn down power using ALC.

The only thing I can figure is the flex using 0 to -4 v and the SPE uses 0 to -11v but to me that seems the opposite problem would happen. You would get too great an output.

I am curious, if you leave ALC on but back down the power on the Flex (which you should have have to do) is there a sweet spot were the amp outputs full power ?

pa0bie

How can I get the ALC displayed again in version 1.4.3 of SSDR ?  I am sure I have seen it in an earlier version.  I used it to preset the output for different PA's and XVTR's with a fixed negative voltage coming from the PA / XVTR.

iz7auh

with answers and suggestions, I tried to do everything that you said, but I remain convinced that ALC is not good, I set an output of 25w enabled ALC HARDWARE menu configurations, but I notice that lying power reductions that lead a provision also 1 / 2w fact the corresponding notice something strange on my signal, I do not think that is my fault but I feel all what had to be done

Lee - N2LEE

pa0bie if you are talking about the bar graph, it only shows when it is actually limiting the amp. 

Lee - N2LEE

Frank that is weird. I wish I knew more about the SPE but all I can say is the Flex 6300 hardware ALC works as expected on my Tokyo Hy-Power, so yes it does work.

Doug Hall

Lee, that's very interesting. Just for clarification: are you saying that you leave your power level (on the 6300) set at 100w (maximum)? And the ALC reduces it automatically for the Tokyo Hy-Power amp? Does it work for CW as well as SSB? How much drive does the THP require for full output?

Lee - N2LEE

Doug, yes that is how mine is setup. I Don't work CW but works for SSB.
I should mention that the THP has an ALC control that you adjust to set the correct ALC level. Its possible this might be the difference why Frank is not working correctly.

As mentioned earlier, the Flex uses zero to -4 volts and the SPE expects zero to -11 volts and wonder if that is contributing to Franks issue.

According to THP the drive is 85-100w.

KY6LA_Howard

@Frank

Dr Gianfranco of SPE claims that the Expert Amps have intelligent ALC that can accomodate any level of ALC.  He also claims that his version of ALC does not cause distortion because it is intelligent.   I have not tested his claims..

I suspect that your real problem is likely that you are getting RF into the ALC Cable which is totally screwing up the ALC action.  As further evidence of the RF into the ALC cable issue, the fact that when you reduced the drive power the problem was somewhat mitigated would be pretty conclusive evidence that you have an ALC Cable RF problem

First Solution.. Put Ferrites on both ends of the ALC Cable.

Better Solution:  Forget about using ALC altogether.. Use Autodrive via DDUTIL to set your input power levels. and then you never need ALC...

The latter is how I run my 2K-FA

pa0bie

Thanks Lee.

I will give it a try.

iz7auh

Hi guys, I write to SPE TECH STAFF and I have this answer: Hi Francesco, I could not help testing instrumental with Flex-6500, but 'I assume that the entrance of this transceiver ALC is too "slow" and therefore not in phase with the actual level of RF energy. This would explain the wide fluctuations of power detected. Obviously this 'involves the inability' to include such an ALC in a loop for dynamic control of the pilot, used in amplifiers of the series Expert and beyond. Reading the manual FlexRadio downloaded from this address, http://www.flexradio.com/downloads/flex-6000-hardware-reference-manual-1-4-3-pdf/ on page 39 and 'written quite clearly that this input ALC should not be used to limit dynamically the power emitted. Vy 73s DX - Ing. Marco Vona (IW0FFK) S.P.E. Societa 'For Elettronica srl Now I wonder what is the use of flex 6500 ALC???? Best 73 IZ7AUH