Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: AL572 or AL80B  (Read 5977 times)
AE5X
Member

Posts: 1464




Ignore
« on: May 22, 2011, 07:39:50 AM »

Mornin' guys,

Just a quick coupla questions for those more knowledgeable than myself (which is all of you) on these Ameritron amps:

They both have similar RF output and prices - is there any reason to prefer one over the other?

The '572 has a 3" warm-up time vs 30" for the 3-500Z in the 80B. I know the reputation of the 3-500Z at least *used to be* superior - is that still the case in their current availability, which is primarily of Chinese or Russian manufacture?

Thanks,

John AE5X
http://www.ae5x.com/blog
Logged

KA5N
Member

Posts: 4380




Ignore
« Reply #1 on: May 22, 2011, 08:23:10 AM »

This question has been asked over and over and the AL80B comes out on top as the winner.
There are dozens of threads on eHam that you can retreive and see the pros and cons.
Allen
Logged
W4VR
Member

Posts: 1214


WWW

Ignore
« Reply #2 on: May 22, 2011, 12:09:56 PM »

It's always preferable to have a single-tube amplifier, but make sure you have a spare tube in case the one in the amplifier fails.
Logged
WB2WIK
Member

Posts: 21837




Ignore
« Reply #3 on: May 22, 2011, 01:21:18 PM »

The 3-500Z doesn't have a 30-second warmup time.  It's instant-on (or perhaps 3 seconds).

The "Chinese" 3-500Zs seem to be okay if you buy them from a reputable reseller.  The "RF Parts" branded 3-500Zs seem fine (to me, I've used a few of them now in various amps) and have a good warranty.  The last non-Chinese 3-500Z was an Amperex (French) tube that came in my new AL-80B back in 2000.  It was fine also and lasted seven years of frequent (pretty much daily) use.

In terms of performance, doubt there's much difference between these two amps but it's easier to change one tube than four.
Logged
WV4I
Member

Posts: 135




Ignore
« Reply #4 on: May 22, 2011, 02:14:09 PM »

I've had 2 of each, 1 x AL-80B right now, as well as currently an AL-82. The AL-80 and -572 are both excellent amps. One tube is simpler than 4, but the -572 puts out about 300 extra watts. The 572 tube gain falls off below 30mhz, the 3-500 well above. You could go on and on. I think the pros/cons 1 vs other are about equal. I'd buy the first later build unit that was reasonably priced I could find, either model. The AL-80B's get beat up less on EHam reviews so probably hold their value better, thus about same price used now as an AL-572, latter costing more new. BTW, both these amps really need 240 VAC. It can be done on 120 VAC with enough amps avail, but not optimal setup, works xfmr harder, etc...
Logged
W8JX
Member

Posts: 13268




Ignore
« Reply #5 on: May 22, 2011, 02:20:34 PM »

Both 572 and 3-500z has directly heat cathode (thoriated filaments) so they are both basically instant on. Also while I have long owned (for 17 years plus now) a Dentron amp with 4ea 572b's in it I would go for AL-80B here. Generally a 3-500 can last 10 to 15 years and more if not pushed too hard. If you find yourself replacing one in a few year or even less you are over driving it and pushing it too hard. It will make 1kw and then some pushed but it will shorten tube life. Run it at 800 or so and it will last for many years. I you have a need to see 1KW out all the time go for AL-572 as the 4 tubes can handle it fine. Also while the 3-500z has a 500 watt dissipation rating and the 3-500ZG a 650 watt rating, these ratings are when tubes are in a envelope with air forced up over tube evenly from base. The AL-82 uses chimneys and AL-80 does not so you will never really see rated dissipation and hence shorter tube life when pushed.  572 does not require a chimney and 4 tubes have a combined dissipation rating of 700 watts so even at 1000 watts out you are well within curve. I still get 1000 to 1100 watts out of my dentron (depending on band) with 55 watts of drive to its 16 year old Chinese finals.
Logged

--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
AE5X
Member

Posts: 1464




Ignore
« Reply #6 on: May 22, 2011, 02:23:28 PM »

Thanks for the comments. I've been reading a ton of eHam reviews - you can get lost in them & forget where you started, pro/con-wise, in a hurry.

I recently added a dedicated 240V line to the shack and now need to justify it. An Elecraft KPA500 was on order but a cost comparison (not just with Elecraft and Ameritron) kinda exposed the comparative expense of that amp based on what it offers, esp compared to THP 1.2, 1.5, etc - so I cancelled the order...

I will have a KW on its way to me before the month is out!

73,

John AE5X
http://www.ae5x.com/blog
« Last Edit: May 22, 2011, 02:26:06 PM by AE5X » Logged

KH6AQ
Member

Posts: 7992




Ignore
« Reply #7 on: May 24, 2011, 05:47:27 AM »

The new 572B tubes appear to be arcing at a high rate. with four of them in the amp it's not reliable.

Logged
W8JX
Member

Posts: 13268




Ignore
« Reply #8 on: May 24, 2011, 12:15:47 PM »

The new 572B tubes appear to be arcing at a high rate. with four of them in the amp it's not reliable.


As long as you buy/get fresh tubes you should not have a problem. Old "new" tubes that have been on shelf for a while are more prone to be a bit gassy and arc.  My amp has been running the same set of 4ea Chinese 572"s for close to 17 years now at up to 2700 plate volts and never had any problems. Still make 1000 watts out with 55 watts of drive too. 572's run in 811 amp may not be run hard and hot enough to keep properly degassed with usage due to plate voltage and current limitations of a 811 amp. At the point where a 811 dissipation rating is exceed, 572's are just warming up.
Logged

--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
K1LEM
Member

Posts: 300




Ignore
« Reply #9 on: May 27, 2011, 07:28:47 AM »

 Grin

As with all things, it depends on what tech ability you have. How much you want an amplifer that can with right 572Bs do the legal limit.
I own a AL 572 and its a question of 572B tube reliability. I experienced some arcing with new tubes, this goes away in time, but trashes the solid state, three transistor bias circuit. Its a half hour or less job to repair, but those with limited electronic bench skills will find this a bane.

Next, does 400 watts or so more power really talk up a big difference on the air?
The on air S meter difference between 1000 and 1300 watts is 1.0 db when rounded down.
Will anyone really notice. No.

Cost of four new 572B is about 200 dollars US- RF parts
Cost of New 3-500Z in same ball park.
Availability of tube? Both remain readily available from venders.

So its a toss up with the edge, probably to the AL80B because most are not technically able to deal with even minor repair issues.
Logged
W8JX
Member

Posts: 13268




Ignore
« Reply #10 on: May 27, 2011, 11:14:10 AM »


I own a AL 572 and its a question of 572B tube reliability. I experienced some arcing with new tubes, this goes away in time, but trashes the solid state, three transistor bias circuit. Its a half hour or less job to repair, but those with limited electronic bench skills will find this a bane.


I am curious, what is your plate voltage? My Dentron runs 2600 to 2700 volts no load depending on line voltage running on 240. Mine has never had a hint of arcing. I wonder if there is a correlation between tube orientation (horizontal or vertical) and arcing. There should not be but my tubes are horizontal. 
Logged

--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
W1AEX
Member

Posts: 85


WWW

Ignore
« Reply #11 on: May 27, 2011, 01:56:28 PM »

I bought a used AL-80B (vintage 1999) back in 2008 and found it to be an extremely reliable amplifier. In the "bang for the buck" rating it might just be the top value in amplifiers at this time. It's small, lightweight, and runs very quietly. The power supply handles its duties without complaint and the single 3-500 should last for a couple of decades as long as you don't abuse it badly. My used AL-80B came with its original tube which was a fairly tired Amperex that could just about make 600 watts output on 40 meters. I replaced it with an RF Parts tube and it easily made the 800 watt output rating on CW. When running SSB it had no problem reaching 1KW on peaks when run with 240VAC on the primary. A big bonus is that it's a very easy amp to work on should the need ever arise. The AL-572 is a fine amplifier, but I would opt for the single 3-500 every time.

Rob W1AEX
Logged

ZENKI
Member

Posts: 1648




Ignore
« Reply #12 on: May 27, 2011, 07:56:07 PM »

There are no reliable manufacturers of 572B's in the world.  You are gambling buying 572B's from any supplier at the moment, it really is a tube lottery. Even suppliers who offer a warranty are playing the same lottery game with their suppliers. 572B's tubes are basically a dead duck with no  future supply guarantees. Why buy into future trouble?

I would stick with the 3-500Z. A more rugged tube and much better IMD performance, its a real transmitting tube that would outlast 572B's by a long margin. Besides why use  4 tubes when 1 or 2 can do the same job with better performance? The days of buying buckets full of tubes down at the surplus store for 5 dollars disappeared 50 years ago!  Its hard really defending  any tube amplifier design that uses multiple  obsolete tubes. Try buying a pair of 8875's for a Dentron MLA2500, thats the future for 572B's!
Logged
W8JX
Member

Posts: 13268




Ignore
« Reply #13 on: May 27, 2011, 08:09:52 PM »

There are no reliable manufacturers of 572B's in the world.  You are gambling buying 572B's from any supplier at the moment, it really is a tube lottery. Even suppliers who offer a warranty are playing the same lottery game with their suppliers. 572B's tubes are basically a dead duck with no  future supply guarantees. Why buy into future trouble?

Not hardly. I think they will be around as long as 5-500Z's.

I would stick with the 3-500Z. A more rugged tube and much better IMD performance, its a real transmitting tube that would outlast 572B's by a long margin. Besides why use  4 tubes when 1 or 2 can do the same job with better performance? The days of buying buckets full of tubes down at the surplus store for 5 dollars disappeared 50 years ago!  Its hard really defending  any tube amplifier design that uses multiple  obsolete tubes. Try buying a pair of 8875's for a Dentron MLA2500, thats the future for 572B's!

Again a 572 is not obsolete. It is also used in audio amps for those that want the best sound possible. Also I would not say the IMD is much better either with a 3-500z. On rugged, some are using 572's that are 30 years old. Mine are 16 years old and still strong.  Now if you were talking about a 3-500z lasting a lot longer than 811's then yes but 572's are tuff tubes and properly cooled they will take a beating.
Logged

--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
AE5X
Member

Posts: 1464




Ignore
« Reply #14 on: June 03, 2011, 06:21:06 AM »

I received my AL80B yesterday, thanks in part to the advice offered here. Prior to installing the tube, I went through it looking for loose parts, cold solder joints, etc - all those things I'd heard about. Didn't find a one - everything looked good...even impressive.

Performs as advertised on the 4 bands used so far. First QSO was with 7Z1HL last night on 20m CW.

At Ameritron's suggestion, I ordered the internal QSK card separately to install myself; otherwise, there woulda been a 2-month wait to let them do it.

I'll install it and re-wire the transformer taps for 240V this weekend.

Thanks to all who offered their opinions in this thread,

John AE5X
http://www.ae5x.com/blog
Logged

Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!