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Author Topic: AL-80 to 6m Single Band Conversion Info  (Read 458 times)
K0XXX
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« on: August 20, 2006, 08:16:38 AM »

Recently, AB5F converted my AL-80 to single band 6m. I have a write-up by him on my web pages in case anyone is considering a similar conversion and would like to see what he has done. The url is:

http://fp1.centurytel.net/k0xxx/AL-80%206%20Meter%20Conversion.htm

Mark, KØXXX
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K8AC
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« Reply #1 on: August 22, 2006, 01:29:22 PM »

What output power have you measured?
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WB2WIK
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« Reply #2 on: August 22, 2006, 02:59:02 PM »

My AL-80 6m conversion is simpler, although the one shown looks fine.

I used only a simple pi-net, re-using the original plate TUNE cap for the new LOAD capacitor; using a 3-30 pF vacuum cap for TUNE and 3-1/2t. 1/4" copper tubing for the tank inductor.  We both use similar parasitic suppressors and input circuits, although I made mine variable (tunable) with the original 10m/12m slug-tuned inductor, just fewer turns and smaller C1 & C2 caps.

My AL-80 conversions typically run 900W PEP output on 6m with 65W drive.  Just a tad less than the amp originally ran on HF.

In general, a "single band" conversion is always better than a multi-band one!

WB2WIK/6
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K0XXX
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« Reply #3 on: August 22, 2006, 08:09:18 PM »

On my Daiwa CN-101L, and I can not vouch for it's accuracy, I show about 800w out with about 70w drive.
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AB5Q
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« Reply #4 on: August 24, 2006, 09:40:28 PM »

Steve (WB2WIK) - Have you taken a look at your AL-80 output with a spectrum analyzer?  I'm curious if your where able to achieve the FCC regulated -60dB harmonic supression with a Pi network.  Curious is all....
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N9XTF
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« Reply #5 on: August 25, 2006, 10:16:13 AM »

I can tell you that Steve's conversion works very well, and is cost effective.

From a standpoint of Pi vs. Pi-L, I use an ICE filter on the amplifier output anyway so I would assume that it would be a moot point.

At some point I would love to have someone analyze my amplifier to see just how 'clean' it is.

73 - Doug N9XTF
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WB2WIK
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« Reply #6 on: August 25, 2006, 04:14:20 PM »

>RE: AL-80 to 6m Single Band Conversion Info       Reply
by AB5Q on August 24, 2006    Mail this to a friend!
Steve (WB2WIK) - Have you taken a look at your AL-80 output with a spectrum analyzer? I'm curious if your where able to achieve the FCC regulated -60dB harmonic supression with a Pi network. Curious is all....<

::Great question.  I did look closely at my very first conversion to 6m, and all spurious were -60dB or lower from the peak power when the measured peak power was 750W.  Well, that isn't quite true, because some close-in spurious signals from the transmitter were amplified; but those same spurs were there from the barefoot transmitter, so I did my best to ignore them.  Never did the same evaluation at 900-1000W output, only because my exciter at the time couldn't produce enough drive to get there.  The AL-80B is in mild compression at 1kW out and I wouldn't be surprised if it violates the standard at that level, but this would be an interesting measurement to make some day.

Since 2x is in the FM BCB and 3x in the pager subband, it's highly unlikely anybody would notice some microwatts bouncing around...but you're right about the standard, it is very strict.

73

Steve WB2WIK/6
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N3JBH
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« Reply #7 on: August 25, 2006, 06:39:41 PM »

Hey Steve i heard you cq'ing over my pager in pittsburgh pa. you have a good fist i may add. them dang spurs any how. :0) ok j/k every one.
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AB5Q
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« Reply #8 on: August 25, 2006, 09:08:20 PM »

I would lean towards adding a LP filter to the back end of any 6m conversion that utilizes a Pi output network. If the ham building the amplifier cannot verify spectral purity, an LP filter should be an automatic addition to the circuit.

My two cents worth....
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