Results of the Amplifier Survey

In April 1998 I ask the amplifier people what do they think what would be the „ideal“ amplifier for dx-peds and contesting. 

Since I am an aircraft traveler when I will go on dx-pedition for a contest my general requirements (or probably better whishes) to an amp for the intent usage are about 1kW out, 160 – 10 meter, easy selectable AC power setting to 120 Vac / 230 Vac, 50/60Hz, moderate weight and dimensions to haul the thing around and an attractive price/weight/power ratio.

My intention was to reach as many as possible of the amplifier people and to receive criteria based on operation experiences, technical items and, very important, RELIABILITY, to find out what specific type would be the right one.

I got many responses and whish to thank you all who sent in proposals, comments, experience reports, hints, etc. (most reports are in English, some of them are in German language). 

Several of the amplifier people have a clear favorite. Others sent comments to several types. I created sections for the amplifiers and a general section for general comments and placed all responses to the corresponding section. Sometimes it does not fit ideally the section.

I also put the survey results of ND3A (tnx Rob) into this summary just to have it complete.

But read what do the amplifier people say:

Joe, K8JOE, wrote:
I currently have two Ameritron's, an AL-1200 for home use and an AL-811 for DXpeditioning. The AL-1200 is great for home. It has instant-on tube, so no waiting, covers 160-10, gives me 1500W out for 100 W of drive (FT-990). I do not use QSK in contesting, as it gives my ears a break and it has been very reliable. The AL-811 is a little bulky, but I have carried it to VP5 and V31 several times. With the right case, it is easy to carry. I put packing in around the tubes and a little on top of the tubes and shipped it as luggage. I have a spare set of 3 each 811's (cost me about $45 US), but have never needed them. I have placed 5th in the world from VP5 twice in the ARRL DX CW contest using it. A little more seriousness may move me to 1.5KW rig, but I can't see the difference another 500 W would make. I did change the fixed loading capacitors to door knob types, because I blew one once when I forgot to switch antennas.

Harry NK9R wrote :
Just some thoughts:
I have had two amps in my ham career. The Heath SB-200 and the Ameritron AL-80A. Both would fit the bill if you are willing to go as low as 600 watts. Actually, if you must have it usable on 110 you will need to stay between 600 and 1000. My AL-80A used to pop the 15 amp circuit breaker as I reached up to 1000 watts. With a 20 amp 110 line its ok. The AL-80 weighs more but puts out about 1000 watts, and is more robust.
The SB-200 is smaller, lighter, is very easy to tune, but only puts out about 600.
Forget the higher power amps, most will not run on 110. 
The solid state amps might work depending on weight, but they might not be able to keep cool enough. Actually that will prabably be an issue with any amp if you are going to use it for contesting and DXpedition style operating.

Gerald, OE2GEN wrote:
seit Jahren verwende ich und wir (OE2DX-Group - OE2S) PA's von Ameritron. Wir hatten mit diesen Endstufen noch nie ! einen Ausfall obwohl wir damit 48 Stunden in der Luft sind.
Ich selbst verwende seit 5 Jahren nun eine AL-1200 (1 Röhre - EIMAC 3CX1200, bis 1.7 KW out) zuvor hatte ich eine AL82 (2x 3-500Z, bis 1.4 KW out) auch andere OM's von uns vewrwenden Ameritron-PA's.
Hatte in 5B4 eine TL922 von Kenwood, einmal und nie wieder, der Thermoschutz bringt dich zur Verzweiflung, auch eine Henry ist unter meine Fingern schon gestorben. 
Also, wie gesagt Ameritron kann ich nur empfehlen, natürlich ist eine Alpha auch nicht zu unterschätzen, aber der Preis!!!

From Rob’s ND3A amp survey results (tnx ND3A):
AA8U: AL-811 performed adequately. AL-811H also used where there were power limitations. Upon arrival at home saw that plate choke was nearly fried - too many 10m QSOs during WRTC-96! Ten-Tec Titan used at WP3X on 160m. Extra baggage but worth the effort. Used to own a MLA-2500B - though a bit heavy, a great amp for dxpeditioning. Given the finances and willingness to haul the hardware, would use Alpha 91B like K8CC at WP3X.

From Rob’s ND3A amp survey results (tnx ND3A):
W0YG: Single tube 3-500Z amps like the Heathkit SB-1000 or Ameritron AL-80B. When overseas, parts available (with luck) and easy to repair.

Dave K8CC wrote:
We took a Ameritron AL-811H to C6A. It runs 600W-800W very smoothly and we had no problems with the amp. Weight is reasonable, but the amp is too tall to fit into a suitcase so one must by an "equipment case".

Rick, DJ0IP, wrote:
Dentron has been out of business for a long time. Ben, DL6RAI, is using my old MLA-2500, but it's been modified a bit by Uli (DK4VW). I believe it used 2x 8873 tubes which were very expensive to replace. As a result, Uli built extra protection circuitry into it for Ben. The rig is very light and has about 1200w output. The only source now is the used market. Try Friedrichshafen.

Don, KC5AK, wrote:
I have lugged my old Dentron Clipperton L to several Caribbean spots with fair success

Robert, W5AJ, wrote:
For travel on DX trip it's still the MLA2500. 120/240 vac input no problem.
The Alpha 76CA received favorable comments the last time this subject was presented - which was interesting.

Bil W8EB/PJ8A wrote:
The Dentron Clipperton L is another good choice, it runs 4 572B tubes. The Dentron MLA 2500 has the 8875 tubes that are very expense to replace if you can find them so I would recommend that you stay away from that amp.

From Rob’s ND3A amp survey results (tnx ND3A):
KA9FOX: Dentron Clipperton L seems to fit under most airplane seats. Used a fold-away luggage carrier to haul the amp, rig and laptop around the airports. See http://www.qth.com/ka9fox/mail_summaries.shtml and click on "amplifiers" to see survey results.

From Rob’s ND3A amp survey results (tnx ND3A):
N3ED: MLA-2500 carried to the Carribean for years. Best combination of output and weight.

From Rob’s ND3A amp survey results (tnx ND3A):
N0FW: MLA-2500 is awesome for an expedition - 1500W out and lightweight. Also took 30L1 to Clipperton - worked great.

From Rob’s ND3A amp survey results (tnx ND3A):
K7BV: MLA2500 for power/size ratio, 160-10m, 110/220V.

From Rob’s ND3A amp survey results (tnx ND3A):
N9AG: J6DX crew carries Clippertons, MLA2500s and SB220s - easy to fix and under 70 pound limit for checked bags. Caribean bugs love the MLAs' ceramic tubes - don't turn off the amps. SB200 and 30L1 are also great traveling amps and fit in a large hardside bag.

Dave K8CC wrote:
I also have bought a MLA2500. This is without a doubt the best expedition amp from the standpoint of size and weight. It is so short it will fit into a regular suitcase. I'll probably take it to KP3 next time. 

Al, GM4BAP wrote:
Much kinder to the pocket is a Dentron MLA-2500. These amps haven't been manufactured for many years, so it's likely that you'd have to an overhaul, replacing the capacitors in the power supply and generally cleaning it up.

From Rob’s ND3A amp survey results (tnx ND3A):
W4PA (Ten-Tec Amateur Radio Product Manager): Ten-Tec Centaur. Three used on recent KH9 expedition. 100W in, 600W out for $749. 
See http://www.tentec.com , QST June 1997 and CQ December 1996.

no specific comments received

Bernd, DF3CB wrote:
Schau dir folgende website mal an wegen kleinen Transistor-DXpeditions-Endstufen:
http://www.kunnallislehti.fi/finnfet/

Tim, N4GN wrote:
Don't forget FinnFet. 

From Rob’s, ND3A amp survey results (tnx ND3A):
N4GN: New FinnFet amplifiers - see http://www.iglou.com/n4gn/h40aa/
Very small but expensive - 1000W out for $3950, 600W out for $3347. (kg for each model - uses switchmode power supplies. Only available directly from Finland factory direct.

Don, KC5AK, wrote:
You might also look at FinnFet

Chris, DL5NAM wrote:
Gewicht : 9 Kg ( incl. NT !!!!!!) - Out: 1KW - Preis: ca. 4k$!

Al, GM4BAP wrote:
If I were to pick my ideal DXpedition amplifier it would be one of the FinnFET range. They are very small and rugged, and used by many of the top expeditioners. However, they are not cheap, so you might need to watch DM/FKr exchange rates. 

Juha, OH1MLZ also wrote the hint to look at FinnFet

no specific comments received

Rick, DJ0IP, wrote:
I bought the HF-2000 recently from QRO Technologies. I chose it because it uses a pair of 3-500 tubes. I prefer these because they need ZERO time to warm up, are very robust, and also quite cheap to replace compared to other, more modern Tubes. I paid about $2000 for the amp, plus about DM 700 for Zoll. I ordered directly from the internet and got my amp delivered to my front door in about 10 days. This amp has a heavy duty transformer from Peter Dahl, and Jennings vacumn relay for fast T/R changeover. I'm able to run my Ten Tec Omni at nearly full break-in with this amp. I get about 1200w out with about 95w of drive.

Jack AK7O wrote:
I looked at several of the amps at Dayton. I was impressed mostly with the Alphas and QRO systems Both start (for the ceramic-metal versions) about $3000. Both are heavy around 100 pounds shipping weight and in 3 or 4 cartons. Both have very good construction practices (I was very impressed as I have personally built 3 myself using Eimac triodes and the 4-1000A.) Both use highest quality components, silver plating on tank circuits, heavy Dahl transformers and full-wave bridge rectifier power supplies. (No cheap voltage doubling circuits in those machines.) 
In my humble opinion they were the best overall at Dayton including all the other names you know. There is NO way around heavy components. I tried to reduce that myself and still had a 125# transformer in my last amp. The Dahl units are smaller and lighter but not light!

Kirk N0KK wrote:
Mike, I prefer Alpha..I use an Alpha 78. But, The requirement for power is 220 for the 1.5 kw out. Its auto tune, qsk, beautiful! And you can find them around for about 1500-2000 for great condition.
Im also one of the anchor ops at W0AIH in Eau Claire Wi. and all we use there for our multi multi station is ALPHA...after all the hours on the air dont think weve lost an amp in 5-6 years now! 

Bob, K4NV wrote: 
Get yourself an Alpha 87A. It is the choice of Dx'rs and contesters and the main ingredient in winning DX contests, bar none. I have been a proud Alpha owner for over 28 years and still have an Alpha S/N 5 that I bought in November '70. It still performs like new. Just a tube replacement now and then. Call Dick Ehrhorn and get on board.

From Rob’s ND3A amp survey results (tnx ND3A):
N6TJ: 3 tube Alpha 76 PA or CA. Transformer in carry-on bag and three 8874 tubes in briefcase. Rugged amp with easy 1500 watts output.

From Rob’s ND3A amp survey results (tnx ND3A):
K7WP: Can't beat the old Alpha 76 series amps - travels well in a Pelican case with tubes in the sockets and transformer in a makeup case.

From Rob’s ND3A amp survey results (tnx ND3A):
NA7DB: Preferred amp is Alpha 76A, 3 tube CA model - very rugged. Alpha 374 also excellent. All 76s modified by Dick Byrd for QSK and WARC bands - used by Voodoo Contest Group. Peter Dahl Hypersil transformer for weight and performance. Pelican hardside carrying case for amp and transformer carried separately. 89A pain to tune and keep going. 76s easy to tune by all. FinnFet prototype failed.

Dave K8CC wrote:
I have been to KP3 twice and took an Alpha 91B. Both times the equipment worked flawlessly. The amp weighs 66 lbs total, but Alpha recommends removing the plate transformer for transport. The xfmr is 36 lbs, and the rest of the amp is 30 lbs. Each had to go into its own equipment case to conform to airline rules, however the total weight is not to hard to manage.

Lee (no call given) wrote:
Perhaps you might add COMMAND TECHNOLOGIES,Inc  for their HF-2500 and HF-2500E as an additional resource!

From Rob’s ND3A amp survey results (tnx ND3A):
YB1AQS: Best bang for the buck Drake L75 - 40W/kg has not been beaten and very rugged. HL1K also recommended for it's 20kg and compact size. L7 and TL-922 and Alphas too big for an airplane traveler.

Bil W8EB/PJ8A wrote:
I go to St. Maarten each year for a vacation and contesting. We are PJ8A in the ARRL DX Phone and CW contests. We just bought the Yaesu FL-2100Z amplifier , it covers 160 to 10 meters, runs 2 572B tubes, weights about 41 pounds, and is 14 X 12 X 6 inches. It will put out about 500 watts. If you can find one used that would be the ticket. 

Al, GM4BAP wrote:
The Emtron amplifiers are built in Australia and offer tremendous value for money.

Rick, DJ0IP, wrote:
If I were doing it today, I would buy an amplifier with 3x or 4x 811 tubes (Ameritron, Vectronix, Ten Tec) because they are small, light, and have about 600w output. They don't need much current (only about 5 or 6 amps from 230v), making them ideal for countries with not so strong power lines.

George Badger (no call given) wrote:
Remember that real power equals weight and will have a minimum size. You can not get around the physics. Specs are designed to make you buy something, not necessarily state the facts. The 110/230V conversion will require a plug change and there is no real universal 230V plug. You will have to carry a set of adapters. The xfmr will probably be a jumper change because of the amperage required on the primary side, anywhere from 20-30A. IMHO< Pput the power gain in the antenna, where it is equal on rx and tx. If you can't hear them, 25KW won't work them.

Mike. KD9KC, wrote:
Amps are nice, but I recommend the best available coax and antennae. This has the added advantage of helping the RX as well as the TX. The gain in using good quality antennae and coax will far outweigh the gain difference between 500 watts and 1000 watts. Have a great trip.

Gary N1MSV wrote:
Darn good point. First and best money should always go to improving the antenna system. The last money to amps. Amps are like the cherry in the middle of the chocolate cake. Would you rather have a KW into a dipole at 20 feet or 100 watts into a 5 element monobander at 100 feet? There is no comparison.

Mike KF2LF wrote:
Take a look at Richard Measures website on the ideal linear amp and his articles in QST. Very interesting reading.

From Rob’s ND3A amp survey results (tnx ND3A):
W8KKF: Watch the weight limit and packing size - excess baggage charge expensive. Give consideration to removing transformers and tubes. Be aware of moisture buildup in high humidity areas.

Dave K8CC wrote:
Three of us might be going to the Pacific for a couple weeks next year. I am looking for a small amp, 500W-700W output, 6" x 6" x 12", 30 lbs.  Nothing exists, but I have a homebrew design on paper. The AL811H is very good for this but too big. Much dead space inside amp - height is set by the 811A tubes. I'd be interested to hear what you find.

Al, GM4BAP wrote:
The main challenge will, I think, be finding an amplifier that operates happily on 120V. I believe the sophisticated PSU of the FinnFET models will handle this, but Alpha (for example) recommend only 230V. 

can be found at:

http://www.qth.com/KA9FOX/dxpedition_amp.txt

http://www.contesting.com/_amps/9704/0425.html   (tnx DK8MZ)

Amplifier Discussion Mailing List. (tnx KC5AK and others) 
To subscribe:
Send a message to amps-request@contesting.com
with the word 'subscribe' in the body of the message.

Richard measures website at http://www.vcnet.com/measures/   (tnx KF2LF)

I will not comment each response individually. But it is very interested what experiences on various fields (practicable hints and kinks, technical issues, commercial aspects, etc) the amplifier people have and I welcome any comment. This really helps to find out what specific type could be the right one.

The Ameritrons, Dentrons and Alphas are mentioned very often. But both the Ameritrons and the Alphas are heavy things, others also. For traveling the best would to transport the transformer and the rest of the amp separately.

The Dentron units seem to be a favorite for dx peds and traveling, but the source now is the used market. I have never seen an offer.

Since I need to run the amp also on 120 Vac (caribe area and others) generally I think an amp with < 1kW output would be a practical choice like the smaller Ameritrons, TenTec Centaur or probably the Emtron or Vectronix. This needs to be checked. Generally it shall be a new one. The FinnFETs look very nice and ideal but the price kills the available budget.

For stationary use with >1 kW I prefer an Alpha. For traveling the Alphas are too heavy 

Well, I hope this short summary is also of interest for others. Take it as a collection of experiences and probably take into account some of the thoughts when you decide on a new amp.

Thank you to all who gave input to this survey.

www.dl1hcm.de / 15.02.2006 / Contact