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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | Ameritron AL800H Help


Reviews Summary for Ameritron AL800H
Ameritron AL800H Reviews: 13 Average rating: 4.5/5 MSRP: $2,599.
Description: Two 3CX800A7 - 1500 watts plus
Product is in production.
More info: http://www.ameritron.com/
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KE4WY Rating: 5/5 Nov 21, 2000 02:45 Send this review to a friend
Good Legal Limit Amp with small footprint  Time owned: more than 12 months
The AL-800H is a legal limit amp with a small footprint. It's about the same size as the popular AL-80B single 3-500z Amp but the AL-800H has two 3cx800a7's and easily puts out 1500 watts power.

For a small package, the AL-800H performs very well.

As mentioned in an earlier post Ameritron's grid protection circuit helps make the amp idiot proof. The protection circuit works very well.
Once I was use to tuning the amp (After the first day)and wrote down the approximate PLATE and LOAD settings for each band that I keep on a small tuning sheet I never see enough grid current to kick the protect circuit while tuning. I tune with a pulsing tone that is easier on the tubes than a steady carrier. It takes me just a few seconds to tune each band. In fact I now have the plate and load controls memorised and do not have to refer to the sheet.

The amplifier handles full 1500 watts output with ease during round tables on 20, 40 and 75 phone with the exhaust not getting too warm. With 45 - 60 watts of drive I am able to get 1500 watts out of the amp. I did not feel the cooling fan is too noisy. I have owned amp's with louder blowers or fans and amps with quieter fans......this amps cooling system appears to fall in the middle concerning noise. Again quite acceptable to me.

In an earlier post by another Ham a concern was mentioned concerning the 80-160 meter coil and melting glue. I thought I would just take a look at mine and noticed it is intact with no signs of heat problems at all nor do I see any glue???

One nice thing, the cross needle wattmeter does in fact appear to be peak. Nice for phone.

For the money I feel this amp is a good bang for the buck with a grid protection circuit that appears to work well. It's a good medium duty legal limit amp at a good price with a small footprint that doesn't dominate the shelf.

I would buy another.

73 de KE4WY Jim

 
KA4P Rating: 4/5 Sep 17, 2000 13:28 Send this review to a friend
Good amp in a small package  Time owned: more than 12 months
My decision to get the AL-800H was based on the need to have a legal limit amp in a small space. Now that I have constructed a whole new hamshack, limited space is not the problem and I may well spring for a heftier 1.5KW amplifier, but so far the 800H retains its place on the shelf.

For such a small package, I must say the AL-800H performs quite well. Installing the tubes was a bit of a chore mainly because of the umpteen screws that hold the cover on. With the cover off, I was able to appreciate the clean and fairly robust construction.

The 3 minute warm up time of the 3xc800a7 pair takes a little getting used to especially after having a 3-500Z amp. The failure of the plate current meter to illuminate was initially disturbing until I read enough of the manual to realize that it was supposed to be this way. (The meter lights up when the cathodes have warmed up).

Some have complained that the 3cx800a7 has wimpy grids (frying above 4 watts dissipation), but Ameritron's grid protection circuit helps make the amp somewhat idiot proof. The protection circuit really does work. I accidentally stuck about 80 watts to the thing one day without increasing the load control. The relays instantly fell out with the overload light illuminated alerting me to my error. Thank goodness! Those tubes aren't cheap. The amp also has a thermal protection circuit which activates if the transformer gets too hot, but so far this has never happened.

60 watts in results in 1500 watts out. I run SSTV and sending high resolution pictures requires 3 minutes key down. The amplifier handles this at full tilt without complaint, although the exhaust gets quite hot after this length of time. I have also noticed that the power will drop by about 75 watts (on my digital wattmeter) during the 3 minute burst. I don't know if it did this when new as I just recently got the digital meter. The analog meter is not sensitive enough to detect the difference. With about 80 watts of drive, I have managed to get nearly 2100 watts out of the amp key down. The plate current was showing over 1.25 amps and the transformer was groaning, so I wouldn't recommend doing this for very long. I was afraid to drive it with any more than 80 watts. The fan noise by the way is not objectionable to me, but I used to have an SB220 (rattle rattle).

Metering is very well done. The left cross needle meter shows plate and grid current all the time, while the right meter shows peak power continuously as the other needle selects between high voltage, relected power, ALC voltage, and ALC set voltage.

Front panel ALC adjust is nice. You can use this to help keep your power output legal, but the real function of this control is to try and limit your grid current. There is also an ALC pot on the rear which limits the ALC voltage and helps keep some overly sensitive exciters from pumping wildly in response to too much ALC. My Icom 756PRO was one of these, but careful adjustment of the rear ALC pot resulted in a smoothe response.

In 2 years of tough continuous duty operation, the only failure has been loss of the multimeter lamp. Replacement requires one to be somewhat of a wizard and I ended up "redesigning" the lamp and replacing the old bulb with a wheat lamp from Radio Shack. My redesign resulted in better meter illumination so when the other meter lamp dies, I will redesign it as well..

The manual is a good one. I especially appreciated the section on tuning and loading with attention to proper load adjustment to protect the grids and preserve linearity.

The AL-800H may not have the biggest transformer, the most robust power supply, or the toughest tubes, but I do feel it is probably the best performer on the market for its physical size. If I do decide to get a fire breathing behemoth, I may well keep the little Ameritron for a backup.
 
N0AH Rating: 4/5 Jan 16, 2000 22:20 Send this review to a friend
Can a better coil be found?  Time owned: unknown months
well, so much for consistancy-

The amp has a small problem- the inductor coil for 80/160 meter is too small-

I found this out the hard way- This coil, from the factory, uses glue, that holds the coil spacing together- I found thatthis glue will melt if a high SWR situation happens-

The first time I found this glue to be a problem was when my amp switch was set on 80 meters and I was on 160 meters- I smelled something burning. After I removed the cover- I found the coil had become shorted accross the turns. The glue, which had melted in the high SWR environment, actually caused the metal of the coil to wedge together-

So I replaced it with another coil- with the credit going to my elmer, K0RF...he made another coil that was actually better than the original- it allowed more inductance so I didn't have to max out the tuning on 160 meters-

That coil worked good- but when the factory coil came in, I decided to replace it- but it did not have the tunability of the home brewed coil that K0RF made- his coil offered just a couple more turns- thats all it takes-

That said- why cant the factory figure this out?? I mean it will tune up on 80/160- but a simple replacement coil did a much better job-

And why use a glue that melts in an environment where heat is a possibility?- I think next time I buy an amp- I will avoid those using inductor coils using glue- there has to be an alternative-
 
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