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Author Topic: New to the KW club - questions  (Read 1158 times)
KG0WX
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Posts: 8




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« on: April 20, 2006, 04:02:23 PM »

I'll probably look like a fool asking these questions, but I'd feel really dumb if I blew up my new amp with bad or no information so, here goes:

1) I bought a AEA LA-30 amp with a brand new 3-500z tube. I don't have a manual. I need to interface this amp with my TS-850SAT (also picked up this month, with manual). Anyone have a copy of the manual for the LA-30 they can email me? my call at hotmail dot com

2) All of my antennas resonate near the center of the ham bands they were designed for. Do I need a tuner between the antennas and the amp? All I use my 850's internal tuner for is to expand coverage on the band edges, like on 75m where my linear loaded dipole only covers 89kc right in the middle of the voice sub band. That's the way I was taught - tuner's just "help" - they won't make a chain link fence give you DXCC.

3) Can anyone help with a little bit of elmering? Yes, I know - I've been a ham 11 years and into radio 15 years before that but up till now my max power was 230w pep. Now that I'll be pushing 1.2kw, I want to be SAFE!

Help?

Ken KG0WX
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WW5AA
Member

Posts: 2086




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« Reply #1 on: April 21, 2006, 06:38:19 AM »

Ken,

The AEA L-30 was made by Vectronics in Canada and now owned by MFJ. You might try MFJ. The L-30 is a solid amp and the 3-500Z is a tough tube and can usually handle at least a 2-1 match or better, however since you are new to amps I would advise a good tuner. Do a search here for tuning an amp, lot of good tips. Good Luck.

73, de Lindy, WW5AA
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WB2WIK
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Posts: 21757




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« Reply #2 on: April 21, 2006, 08:16:25 AM »

Fairly rare amp, hope you can find manual.  I checked with the usual on-line sources and they don't have it.  W7FG.com and Manualman.com, who sell manuals, don't have it listed, either.

However, you could use a Heath SB-1000 manual.  It's basically the same amp with a different case.  That manual's fairly easy to find.  The Ameritron AL-80B manual is free and on line (http://www.ameritron.com) and is also very similar functionally.  Adjustments are the same, as is tune-up procedure.

A good tuner's never a bad idea, however if your antenna system SWR is <3:1 or so, the amp will probably load into it and transfer all available power just fine.  Easier than adjusting tuners is making antennas more broadbanded.  Your loaded 80m dipole can probably be made more broadbanded by adding end loading wire of various lengths, fanned out over a bit of space, to make it resonate on 3.5, 3.6, 3.7, 3.8, 3.9, 4.0 MHz.  I do that, myself -- works.  And as I said, easier than playing with tuners all the time.

WB2WIK/6
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NI0C
Member

Posts: 2947




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« Reply #3 on: April 21, 2006, 08:27:09 AM »

Lacking a manual or other information concerning interfacing-- here's how to get started on the interface question.  See if you have a rear panel connection marked "relay," or "T/R."  With the amplifier turned on, measure the open circuit voltage. and check to see if it is AC or DC.  This is the T/R relay voltage.  Next, set your DMM to measure current.  Short the T/R connections with the meter.  You should hear the T/R relay click, and the relay current will be displayed on your meter.  

Now compare the open circuit voltage and short circuit current values to the ratings given for the TS-850S to see if you need a buffer or interface circuit for T/R switching.  If you do, I recommend the "Amp-Keyer," sold by Sunlight Energy Systems.

With regard to a tuner or transmatch at the amplifier output, you can probably get by without one.  I don't use one with my AL-80B amp (also a 3-500Z tube).  

73,
Chuck  NI0C
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WB2WIK
Member

Posts: 21757




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« Reply #4 on: April 21, 2006, 11:35:04 AM »

TS-850S has a fairly hefty keying relay, so this shouldn't be a problem.  The LA-30 uses DC keying.  Don't forget to switch the keying relay to "on," on the rear panel (little slide switch), otherwise the relay doesn't work at all.

Actually, if the LA-30 works as it should, nothing here should be a problem.

It's a simple amplifier that tunes up exactly the same as the SB-1000, AL-80B or any other amplifier.

I use a TS-850S to key every amp in the house, and it's done so successfully for years (no external interface needed).

WB2WIK/6

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PA0FRI
Member

Posts: 31


WWW

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« Reply #5 on: October 04, 2006, 07:09:02 AM »

I have just updated my homepage with a AEA LA-30 manual and pictures:
http://www.xs4all.nl/~pa0fri/Lineairs/LA-30/manual.htm
73, Frits
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