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Author Topic: Amplifiers, tuve vs solid state, opinions please  (Read 4569 times)
W7HBP
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Posts: 164




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« Reply #15 on: March 09, 2013, 07:28:57 AM »

Thanks for all the good advice. I do have a dummy load, but its only rated for 300 watts. I did purchase the new LDG AT-1000-PROII tuner. 1.5KW dummy load is next.

I will search online to find a set of those plastic hex to adjust the input SWR if its even needed.

I like the idea of solid state 1KW and >, but for a $3000+, the price was astronomical. Maybe later on down the line.

This should help me fill my DX log book much faster.  Wink
« Last Edit: March 09, 2013, 07:38:47 AM by W7HBP » Logged
W7HBP
Member

Posts: 164




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« Reply #16 on: March 09, 2013, 07:37:11 AM »

If you ordered a new one, the 15/17 meter broad banding mod will already have been done. The newer input board doesn't have the jumpers on the outside edge. It should work out of the box. If in doubt about the 15/17 mod, Ameritron can tell you if you give them the assembly date off of the HV board.

KB5UBI

I suspect you are right. I was told that the "B" model, the 15/17 meter mod is done. I'll report back with all my findings. Hopefully, just a quick 10/12 meter mod and its all right in tune. Fingers crossed.  Grin
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W5LZ
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Posts: 477




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« Reply #17 on: March 10, 2013, 08:15:04 AM »

The preceding posts pretty well covered thing, so this is just a few random things I've found from using both the AL-80 and the AL-80B.
If given a choice, I'll operate an amplifier on 240vac rather than 120vac.  Less 'sag' (local power comp[any mostly, I think) and just not that big of a problem to run the line.If it's used reasonably, don't make too many mistakes, a 3-500 tube should last for quite a while.  It's not a bad idea to have an extra hidden away though.  They are never going to get any cheaper, and at some point, you will need to replace that tube (stuff happens sort of).
While you're at it, get a box of extra fuses too.  No, they shouldn't 'pop', but...
Pay attention to those meters on the thing!  Don't hypnotize your self watching them, but sort of watch them to see how they react when things happen.  That grid current needs to be less than the max for a very good reason, and that's where having that extra tube comes in handy.  Plate voltage will vary, depending on your power company.  Shouldn't be a large variation but there will be one (at least if you have my power company!).
That thing does need to 'breath' so give it some room to do so.  Everyone talkes about fan noise, but I haven't found that to be a problem.  Yes, they do make some noise, but nothing exceptional.  Of course, if that changes, then start looking for the reason for that change.
I've also found that using a air conditioner filter over the input grill to be a nice thing to do.  I use a couple of magnets to hold it on.  Not an important thingy, but one way to keep it clean (and stop some of the random small 'pops' you can hear occasionally, why do bugs want in there to start with?).
Check connections every once in a while.  Not much, but they do vibrate and tightening things up isn't a bad thing to do.  It doesn't hurt to set things on top of most amplifiers but check for heat before you put you iced tea up there, it will melt ice.  It's not going to keep your coffee hot, but doesn't do much for cold beer either.
Don't expect to get full output on all bands, or any band all the time.  Close, sure, but that depends on the antenna system a lot.  There's no practical difference between full output and almost full output except for parts replacement and ego.  If there's a fairly big difference in 'normal' output, then it doesn't hurt to find out why.
Any of the above can apply to almost any amplifier, it's not specific to the AL-80.
Have fun.
 - Paul
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KC4MOP
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Posts: 728




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« Reply #18 on: March 17, 2013, 03:48:24 AM »

Have a demo of one of the new Acoms.

It's totally idiot proofed and I can tune a new band in less than five seconds.

You get what you pay for, as the saying goes.

An amp for life? Buy the Acom1000 for a few hundred more...

The Acom may be at the very best of the best. BUT I read that the ouptut tubes are very critical for balance and must be special ordered from Acom. It gets really expensive!!
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W9KDX
Member

Posts: 770




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« Reply #19 on: March 21, 2013, 09:09:48 AM »


....I will search online to find a set of those plastic hex to adjust the input SWR if its even needed....


I had a terrible time finding them until I went here:

http://www.mtechnologies.com/tools/
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Sam
W9KDX
K6AER
Member

Posts: 3468




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« Reply #20 on: March 21, 2013, 10:12:27 AM »

The ACOM 1000 uses a single tube. What is to ballance?
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KC8OJU
Member

Posts: 31




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« Reply #21 on: March 22, 2013, 01:20:05 PM »

I already have all the parts except the cabinet to build a
 4-1000a tube amp took me years on a shoe string budget.

Now I see they have 600w mosfet linear amp HF kits for under 500USD.
Now  I can afford a cabinet for the 4X1 and get the 600w kit to boot.
I'll use the 4X1 in the winter to keep me warm and the 600watt mosfet in  the summer when things heat up in the shack.

Tubes are becoming scarce and SS is becoming obsolete you just have to go with the glow.
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K2UE
Member

Posts: 34




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« Reply #22 on: March 24, 2013, 12:29:41 AM »

After spending the last 10 years of my career as an RF IC designer, and owning several HF solid-state amps and the equipment to test them, I have reached some conclusions:

Tube amps have the reputation they do for reliability because they are further away from catastrophic breakdown -- it takes well above normal voltages to produce non-catastrophic breakdowns, which often fully heal, and thermal overloads take longer to cause irreversible damage.

Solid-state amps are relying on devices with internal dimensions measured in angstroms and microns, breakdowns are almost always catastrophic, and thermal overload produces rapid irreversible damage.

Add to that that tubes amps normally have output networks that allow tuning to an essentially perfect load-line, whereas solid-state amps are sold as supposedly tolerant of slightly mismatched loads.  The reality is that for good IM and reliability EVERY amp should have a tuner of some sort to provide an optimum load, and solid-state amps need them MORE than tubes because of their less robust nature and typically poorer linearity.

My own shack is a mix:  an Alpha 87A for HF, and M2 solid-state amps for 6m and 2m - with line flatteners for 1:1 SWRs.  My 432 tube amp will be replaced with solid-state as soon as the technology and costs allow.
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