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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | Alpha 374 Help


Reviews Summary for Alpha 374
Alpha 374 Reviews: 13 Average rating: 4.5/5 MSRP: $alpha 374 manual
Description: ALPHA Legacy Amp w. 2 x 8874's
Product is not in production.
More info: http://www.rfconcepts.com
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KA9P Rating: 5/5 Sep 11, 2013 10:03 Send this review to a friend
BIg value  Time owned: 6 to 12 months
I picked up an elderly 374 and a 374A at really good prices after placing an ad for an Alpha with weak tubes to upgrade to 3CX800's. They're out there, and in my view the paranoia about marginal tubes is pushing the price down well below the value of these amps. You could not touch the parts quality, let alone the build quality, for what some of these are going for now.

This 374's tubes are a bit anemic on 10, doing only about 800 watts out, but exceeds a KW on bandpass on every other band. I've run it flat out for six months now, and it's been extremely well-behaved and is a really well built brute, and I expect to leave it as is for a while as the 374A is more easily adapted space-wise to the 3CX800s.

I've found several good used 8874's at 200 bucks a piece or less (only 1 performed worse than advertised)so if you're not inclined to do the popular 3CX800 conversion you're not out of luck, either. And the grid monitoring in the 374 is a big plus, not sure why that was dropped as a standard feature in the later amps.....
 
KH6P Rating: 5/5 Apr 2, 2013 17:08 Send this review to a friend
Excellent Amplifier  Time owned: more than 12 months
I bought my Alpha 374 in the early 80's from another ham, and have used it on the air ever since. Originally, I drove it with a TS-130S, then an Icom IC-751A, and now with my Elecraft K-3. The Alpha is still going strong on the original 8874's, although I have three new ones in reserve, should I ever need them. The amplifier will work on all bands 80 through 10 meters, except 12 meters, and has pretuned band switch positions for 80, 40, 20, 15, and 10 meters, so changing bands is a smap, no manual tuning needed. I leave the manual tune position for 20 meters set up for 17 meters, so I am ready for that band as well. The only modifications that I have made to the amplifier is to send it to Dick Byrd (N4UQ) to incorporate his solid state QSK circuitry, which eliminated the relay noise. I recently bought a new RF choke that is not resonant at 25MHz, and once that is installed, the amplifier should put out 1.5KW PEP on 12m as well. Bottom line, a very solidly built, reliable amplifier.
 
W8LAD Rating: 4/5 Aug 24, 2012 09:59 Send this review to a friend
Very well built !  Time owned: months
I have worked on several HF amplifiers (FCC and SBE certified) in my amateur "career" and of course some are built (form and function) better than others. My latest HF Amp repair job was on a PALSTAR HF2500...two weeks ago, and I must say it is a well built "machine".
Changed considerably from the original design by my friend Pat Stein...but still a decent amp.
However, this week I had the opportunity to evaluate a 1980's vintage HF Amp, and after removing the top cover I began to see all the reasons why an ALPHA is an ALPHA ! I was looking at the "guts" of an Alpha 374...and it does have "guts" ! This was my first look at an Alpha, and though it is a "vintage" Amp...it was built with very high quality parts...Almost as though someone might put a brick on the key and walk away ! I beleive my "retirement" Amp is going to be an ALPHA !
73, DE: W8LAD
 
N4NW Rating: 4/5 Apr 16, 2012 18:22 Send this review to a friend
My 1st Alpha  Time owned: more than 12 months
My first Alpha was the 374. Using three 8874's (3CX400) tubes it was the first almost no tune, full legal limit HF amp. Of course you did have to change the band switch.

I used in the 70's with several different transmitters, all of which like working with the 374.

If you needed the ability to quickly change bands and did not want to spend time tuning a PA then this was the amp for you.
 
AK0O Rating: 5/5 Dec 28, 2011 07:27 Send this review to a friend
Very Easy to operate  Time owned: 6 to 12 months
My Alpha 374 has three 8874's, the manual reads as though this is normal and not a mod. So I am wondering if some 374's were two tube models and some three tube models. The amp puts out from 900 to 1200 watts in bandpass mode depending on the band I am operating on. Very quiet and cool running amp. I like the bandpass mode as one does not have to do any plate or load adjustments, just turn the selector to the correct band and present less than a 1.8 swr to the amp! How easy can you get.
I received this amp from a guy who seldom used it, he got it from a guy that used it as a standby amp, the amp does look like it just came off the shelf at the store. I plan to use it till the tubes dies than do the tube upgrade. Of course if three 8874 tubes came around I would continue to use the amp as is.
If you see one used buy it!
 
KR4JA Rating: 5/5 Sep 6, 2011 10:39 Send this review to a friend
Excellent vintage amp  Time owned: 0 to 3 months
I just picked up a 374 (thanks Randall), in immaculate condition, silver front, no sticky paint. The only mods I can tell are the addition of a 3rd tube and the RCA input has been changed to an SO239. The amp runs quiet and gives me 1000-1200 out in bandpass mode on each band (legal out with manual tune).

I may eventually upgrade the amp to 2 x 3CPX800A7s (like my 76PA, which was upgraded by N4UQ), but for now the 3x8874 tubes are full output and draw <20ma grid current at 1200W (SSB) using the bandpass mode. This is a great vintage amp (built in 1976-7) which uses a large oil-filled capacitor in the HV supply, a Hypersil X-Frmr (Iím getting ~2350V on high tap), and far surpasses the quality of other no-tune amps Iíve had (which include a Hercules II, 2KL, LK450NTC, and LK500NTC).
 
NN3RP Rating: 5/5 Nov 8, 2010 12:09 Send this review to a friend
Excellent Performer  Time owned: 0 to 3 months
Over a month ago I picked up a 374 here @ Eham
3 x 8874 = 374
SN 3265

Not too many of this model were made by Alpha.
This one had been modified with special larger knobs for Tune / Load. The knobs have numbers from 0-100 while the original numbers are behind each knob on the faceplate. This will make for real fine adjustments on Tune / Load. I particularly like these larger knobs.

When I first got the amp, it came with the power cord almost roasted / cracks all along. It was dangerously bad a power cable. The light bulbs were also out. I power it up like this just to see how it will performed but I was disappointed to find out that I could not manually fine tune it following the user's manual instructions. It will work just fine in no-tune mode but the power out was not to my satisfaction. Something was not right, I thought.

The former owner refused to get it back. So I was left with the issue.

Bring Richard Byrd, N4UQ!!!!

A search on the web pointed to Dick as a person who deals with this brand of amp so I contacted him. After several phone calls and emails explaining the issue, Dick took the amp for troubleshooting.

Dick replaced the power cable and lamps. He also measured the temperature on each of the three tubes and they were all the same. Fortunately, he told me, there was nothing wrong with the manual tuning. What I was missing was the proper Tune / Load positions. He made for me a test data sheet from 80-10M so I just simply place it in that spot when changing bands and adjust a bit. Dick was surprised to see the unusual knobs himself but admitted it was a good thing to have. It cost me not much to have the work done by Dick. The satisfaction of knowing that the amp was in excellent condition was invaluable to me.

Now this amp can go close to the power limit or more??? With about 60W, it can fly very close to the limit and the green light starts to flicker. It takes about less than a minute to warm up. I keep it in SSB at all times no matter if it is CW / SSB the mode I am using on the radio....linearity!

Now its fan is noisy and I even added an extra large PC fan to aid it in cooling the tubes. It also makes a clacking noise when TX. I don't care much about the noise since I only use it for contesting mainly. One call and it breaks the pile-up!!!

It helps much to have a XYL as amateur radio operator too...hihi

My $.5
 
N5UD Rating: 4/5 Oct 23, 2010 08:55 Send this review to a friend
Good 3 holer but noisy  Time owned: more than 12 months
I bought one new circa 1975. Quality Alpha build, but blower system was noisy. I even found it to be noisy when operating with the cans on. Bandpass mode picky as to what kind of load it was operating into. The protection circuits did work hi hi. I used manual tune some times.

If I came across one used, I would want to check out on all bands. Those 374's sure are expensive. So would be any bandswitch problems.
 
KC5BHJ Rating: 5/5 Apr 30, 2007 09:04 Send this review to a friend
Great Amp  Time owned: 0 to 3 months
The 374 is a great amp, period! Just getting back into ham after a 7 year layoff. I looked and looked for a used Alpha. I found a used 374 on ebay. Paid $ 1,275.00 for it plus shipping ($ 300.00 for next day). It had dyno tape on the face plate. After removing it, I pluged her in, turned her on, set the band switch on "no tune" on 80 meters. Set my FT-100MP at 60 watts out, said hello and low and behold...1250 watts out!!
How simple can it get???
I get unsolicted excelent reports on my signal all the time.
Before, I ran a Alpha 89 and a Ten Tec Titan 425, both great amps...but this 374 is as good, if not better...
All I can say, if if you find a good one, BUY IT!!!!!!
 
WB2CMA Rating: 5/5 Sep 25, 2005 11:36 Send this review to a friend
BUILT LIKE A TANK, ROARS LIKE A LION  Time owned: 0 to 3 months
FURTHER INFO ON ALPHA 374 AMP.
ATTRACTIVE SLEEK DESK TOP DESIGN WITH FRONT FOLDING TILT STAND "BAIL" WEIGHING ONLY 52 POUNDS. ELABORATE PRESURIZED 115 CFM FORCED AIR FULL CABINET COOLING WHICH VENTS TO THE REAR, PLUMING DESIGN WHICH LOOKS LIKE SOMETHING FROM UNDERNEATH THE HOOD OF A NASCAR RACE CAR!.THIS ALLOWS YOU TO PLACE OTHER GEAR ON TOP OF AMP. SILICON STEEL (HIPERSIL) TRANSFORMER, MAXIMUM POWER INPUT 3 KILOWATTS PEP/SSB OR 1 KILOWATT AVG. KEY-DOWN CARRIER D-C INPUT, CONTINUOUS DUTY, NO TIME LIMIT. CONTINUOUS MANUAL TUNING 3.5 TO 30 MHZ. 120 OR 240 VOLT 50-60 HZ OPERATION. 1.5 KILOWATT+ PEP/SSB, 600+ WATTS CARRIER RF OUT-PUT. ELECTRONICALLY-CONTROLLED TUBE WARM-UP TIME DELAY APPROX 60 SECONDS. PLATE HV OVERCURRENT RELAY PROTECTION. ALC EXCITER CONTROL. BANDPASS NO-TUNE
FILTERS FACTORY ALIGNED FOR OPTIMUM HIGH POWER SSB OPERATION INTO 50 OHM 1.5.1 VSWR OR LESS 80 THROUGH 10 METERS. MANUAL TUNING 2.1 VSWR OR LESS.
CABINET TOP AC INTERLOCK AND HV B+ SHORTING BAR PROTECTION. SILVER PLATED RF TANK COIL AND HEAVY DUTY CERAMIC SILVER PLATED BAND SWITCH. 3KV PIV/SILICON STACK 100 AMP DIODES IN FULL-WAVE BRIDGE CIRCUIT, "NO VOLTAGE DOUBLER CIRCUIT HERE"
TRANSFORMER HAS THE JUICE. BEST RF POWER OUT-PUT TO WEIGHT RATIO OF ANY AMP EVER BUILT THEN AND
NOW. JUST THOUGHT U LIKE TO KNOW A LITTLE MORE ABOUT THE ALPHA 374.

DAVE WB2CMA
PROUD ALPHA 374 OWNER






 
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