Date: Fri, 23 Feb 1996 07:20:48 -0500 From: AB5YG@aol.com Here is my input / recommendations concerning the Ameritron AL-1200 and AL-1500 amps: I used a brand new AL-1200 with 3CX1200A7 tube during the CQWW SSB contest at the end of last October and for about 2 months afterwards (a friend of mine bought it for the contest). I ran the amp at 1500 watts out on all bands for the entire contest and it was solid as a rock! Tunes very nice on all bands - the vernier loading contols are nice. The AL-1200 uses the Eimac 3CX1200A7 ceramic / metal power triode out of the Varian power grid and x-ray prducts division. The tube is very rugged and has a Grid disdipation of 50 Watts! This tube is just about an "instant on tube". One would really have to try hard to kill this tube. A friend of mine has a Henry amp with a 5 volt filament verion of this tube. Henry runs around 4kv on the plate - Ameritron runs 3300 key down--- I also used the AL-1200 during the ARRL 160M CW contest in December. The antenna tuner arced couple of times - never bothered the amp at all!! I placed an order for the AL-1200 for me in November. In January I changed my mind and decided to buy the AL-1500 - this is why --- 1. The 3CX1200A7 takes a full 100 watts drive to get 1500 watts out. That means running my Omni-6 at full power out all of the time --- The AL-1500 3CX1500A7 takes about 50W max to get 1500 Watts out on all bands! My Omni-6 loafs along at 30 - 50 watts output!! 2. The Filament on the 3CX1200A7 draws 21.3A at 7.5V = 160 Watts - The Filament on the 3CX1500A7 draws 10.5A at 5.0V = 52.5 Watts -- (The AL-1200 is a real heat generator) 3. The 3CX1500A7 is a ceramic and metal, power triode out of the Varian Eimac Power Grid Tube Division. The maximum grid dissipation is 20 Watts -- So you need to watch this a bit closer. The AL-1500 does have a grid current sensor/shutdown circuit that protects the tube. The tube is not instant on! It takes a full 3 minutes for the filaments to reach the proper temp and then the power relays pull in via the 3 min timer. If I was using a rig with over 100 Watts out I may have stuck with the AL-1200. It would not be good to hit the AL-1500 3CX1500A7 with 150 watts drive!!, although the grid current protection circuit would take the amp back to "stand-by". An inexperenced operator may be better off with the AL-1200 because it would be difficult to kill that amp. Another thing of interest is the 3rd and 5th order Intermodulation Distortion Products ratings of the tubes-- 3CX1200A7 3rd is -30 db at 3500 EP, 5th is -43 at 3500 EP 3CX1500A7 3rd is -38 db at 3500 EP, 5th is -41 at 3500 EP Other observations common to both amps: 1. The blower is very very noisey!! A vaccum cleaner is louder though!! 2. The antenna relay is loud - but built like a rock 3. All coils are air wound - no torids in output -- Better?? I think so --- You can change the blower motor speed by moving a tap (soldering required) 4. Modification to go above 15M is very easy!! (could do with eyes closed) I thought about buying the amp with the internal QSK installed --- I decided not to do so because if anything happended to the QSK pin diodes it would mean returning the amp to the factory -- that would be a real pain!! The factory "rep" actually recommended that I buy the external QSK box -- as the cost was the same and it could be used on any amp I have! I have had my AL-1500 for over a month and really like it -- Very rarely does the grid current ever exceed 25Ma and I only triped the grid current once - Ran amp into an open!! Not the best thing to do --- but the grid protection does work fine!!. The amp runs fairly cool at 1500 out -- The case next to the tube warmed up a bit after a 1 hour SSB QSO where I did alot of talking. I ran it during the 160M CQWW CW contest this January - It remained cooooool ---- I have not received the QSK box yet -- It has been on back order for over a month -- Last May I had a deposit on an Alpha 89 - 3CX800A7 (2) Amplifier - for considerable more money -- I cancelled the order when household expenses became primary importance - hi hi --- I had the unit on order for 2 months prior to cancelling the order --- thats one of the problems with having to wait so long - one can change his or her mind!!! Oh well --- The Alpha 87 and 89 are rock solid amps and they are QUIET!! Not like being next to a jet plane taking off!! But the cost is $1000 more!! ETO had a Alpha 89 running at 1500 Watts out for ever at Dayton last May!! Getting back to the Ameritron - I like meters!!! Don't know if I would have liked the Alpha "Light Show" - Well - Hope that this helps you with your selection ----- 73's Bill AB5YG ab5yg@aol.com