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| Reviews Summary for QRO HF2500DX |
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Reviews: 42
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Average rating: 4.9/5
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MSRP: $4095.
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Description: Please go to http://www.qrotec.com/specs25.html
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More info: http://www.qrotec.com/
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You can
write your own review of the QRO HF2500DX.
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W2RD
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Rating: 5/5
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Oct 4, 2008 10:05
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Great Service
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Time owned: 0 to 3 months
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I purchased a used HF 2500 from a friend. The amp worked fine with drive applied but would draw excessive plate current when idle at my QTH. I was unable to fix the problem because I believed it to be a bias problem. I sent the amp to Ray and he diagnosed the problem to a defective diode in the screen grid voltage supply. He replaced an entire board with an upgraded one and sent the amp back to me. It now works perfectly. I know Ray spent a lot of time on my amp because he could not duplicate the problem I was seeing and we had numerous telephone conversations. The diode only failed at my QTH because my utility company is supplying me with 254 volts. The pleasant suprise was Ray only charged me for his labor and did not charge me for the new board. I believe that Ray's dedication to repairing one of his older amps is commendable especially since I am not the original owner.
This amp is replacing my Amp Supply LK550 which needed three new 3-500Z tubes.
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K1XV
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Rating: 5/5
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Mar 8, 2008 06:50
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update of my 2000 review
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Time owned: more than 12 months
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I purchased this great amplifier amp in 1998, and reviewed it back in 2000. I still have it, and it is still going strong. About 3 years ago I rotated the tubes with a set that I had gotten on eBay from a fellow in Lithuania. It still has full output.
I also sent it back to Ray for updates back around that time. He lowered the screen voltage from his original early design, and reduced the recommended screen current for max output. The unit still loafs along at the legal limit.
The supply of surplus GU74b (4cx800a) tubes seems to have dried up a bit, but I still have two spare sets, and the originals, which I think are still fine. You can find them, but they are more expensive than they were. But still much cheaper than any Eimac tube.
This amp soldiers on and on. Its the best.
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WN9D
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Rating: 5/5
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Mar 8, 2008 05:10
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Excellent Amplifier
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Time owned: more than 12 months
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The amp has operated flawlessly since I purchased it in March 2006. I had an issue several months ago with internal fuses blowing. A trip to the factory solved that problem. Ray is great to do business with. He returns phone calls and e-mailings. That is somewhat rare in this day and age.
For the sake of brevity, I'll refrain from restating all of the wonderful things mentioned in the reviews of this amp. They're simply true!!
The proverbial bottom line - this is a great amplifier at a reasonable price. It is simple to operate and to maintain.
Thanks to QRO, this is the first and last new amp I'll ever purchase!!
'73, Randall WN9D
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AD3G
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Rating: 5/5
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May 19, 2007 10:56
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NONE BETTER
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Time owned: 3 to 6 months
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Probably the last HF amplifier you'll ever have to buy. Overkill construction, excellent design. Loafs at legal limit,tunes by the numbers,repeatable settings from band to band. Other than the convenience of autotune,I don't see a better amp on the market at the present time. Have sold all my Alphas in favor of the QRO's ( I have the HF2000 also),the QRO is better built,has a better design,and,unlike the newer Alphas,is field sevicable,not full of microproccessors .
The only downside is the fan (actually it's the moving air) is a bit noisy,louder than my QRO HF2000,but pressurized cooling usually is a bit louder than the muffin fan used in the HF2000,but overall,undoubtedly the BEST legal limit amp I have ever owned.
Hats off to Ray for an excellent product!!
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K9WMM
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Rating: 5/5
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Apr 9, 2007 10:10
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Great brut force amp
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Time owned: more than 12 months
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I have had the amp for 4 years. Bought it new from QRO.I had a few minor problems. A relay had a bad internal connection which I resoldered. I was having probelms with the 400V PS and blown fuse. Ray gave me advise on how to fix it. The amp put out 2,500 watts into a Bird 5KW oil filled dummy load and measured with a Bird as well. It loafs along at 1,500 watts. It is not fancy with micro processors, but something you can FIX yourself. If you can't tune your amp, what good are you? This is a Ham's amp! I have built a few of my own linears so I know a little about them and construction. This is a very good amp!
Ray gives you the best service and advise either on the phone or by email. If you want a piece of equipment you can fix and something that will last your entire Ham carear, this is it!
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K0RU
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Rating: 5/5
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Dec 26, 2006 19:31
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Excellent Product & Service
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Time owned: more than 12 months
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Hello I purchased my QRO Technologies HF2500DX amp 1998/99 almost 10 years ago. My age is 46 and I've been a ham for 36 years. I operate mostly cw and high speed cw at that. While operating I only operate QSK period VOX puts me to sleep. I've owned many of amps by the X-brand companies and all claim to operate QSK etc, etc. I say BULL!@#T... IF you can't operate QSK full throttle at 80 wpm then your not QSK period.
Well I called RAY at QRO and began a conversation with him regarding QSK I explained to him what I do while operating, my operating practices and exactly how I operated. He stated the amp will do very fine for you, if for any reason it won't I'll gladly modify it to your expectation if you’re not totally satisfied. Hmmm, encouraging but I'm not ready to drop the big bucks just yet... I had attempted to request a manual from X-Brand amp manufactures to include all drawings and schematics... Not one of them would send me a manual let alone any type of drawings. When I requested this same info from Ray his immediate response was "yeah sure, I'll send one out in the mail tomorrow" ok, I can tell that isn't going to happen. Anyway I get off the phone and get on the air and operate. Wow, to my total surprise in a couple of days a package arrived from QRO Technologies in it was the owners manual, drawings, schematics, hell even the circuit board layout drawings I was totally impressed. I read the manual front to back drawing by drawing it appeared that if I were to having any troubles with this amp I would have everything I needed to diagnose and troubleshoot this amp and make the repairs myself if I needed to. Time to spend the big bucks....
Placed my order, QSK, 10 Meters, whole ball of beans... The amp arrived within days. You get the feel for how proud Ray is of his amps when you first receive them. First they are packaged excellent. The transformers are shipped separately (they are heavy) and the tubes are packaged separately. When you receive the amp, you will get your first taste of the quality that goes into this amp you have to remove the cover and install the tubes and transformers while doing so you can help but appreciate the quality of components and the workmanship that goes into this amp it is truly a Work of Art.
Now I operate QSK and I operate high-speed QSK which means I put the pedal to the metal and hammer when I'm working a contest, I'm full throttle (yes fast as the keyer can go on the mark 5 which by the way is only 45 wpm) and the amp sails along smoothly riding along punching thru pileup after pileup. Ok, so now I'm tired of this slow speed keyer on the mark 5, its just way to slow, time to buy a real keyer. I purchased the best of the best when it comes to keyers LogicKey K5, this thing will smoke it.. I send using a Bencher Iambic paddle, and I can send upwards of 60 wpm in a RAGCHEW not this 599 KS 73 crap, I ragchew for hours on end at those speeds using my paddles. Well the amp was ok upwards of 45 now at 50 and 60 hmmm that’s another story. You see the transition from Receive to Xmit on the amp is done using a Vacuum relay if you fire the relay at the exact same moment your transmitting RF thru it, there is the possibility of what is called a FLASH OVER on the contacts... Yup... when operating QSK in the past with my Yaesu FT1000MP Mark 5 I was using the XMT GRD output on the back of the rig and sending that to the XMIT GRD on the amp which completed the sequencing circuit for the QRO to go into Transmit mode thus firing the vacuum relay. Simple and effective at least when running QSK at below 45 wpm, not at higher speeds the relay will flash over and STICK!
Mine stuck, now I'm dead in the water the amp won't key properly and nothing I can do fast enough to prevent blowing the 1-1/2 amp AGC fuse on the LV/BIAS circuit board. Replace the fuse and life goes on... Anyway this becomes annoying at times and I would forget to not push the speed to high for the sake of that poor little fuse blowing again. Ok, enough of this, placed an email to Ray who immediately returned an email stating he was on the road and would gladly give me a call once he was back. We'll Ether he got bored and forgot or was just impatient in any case he calls me almost immediately and begins explaining blow by blow, wire by wire, step by step on how all this sequencing process takes place. He stated the vacuum relay most likely had experienced a flash over and was stuck. I then fired up the amp and began thumping the amp with a transmit signal (NO RF, just keying it rapidly) and BINGO the relay released and away she went... Hmmm, I asked Ray if I could purchase an extra vacuum relay to put in parallel with the one in there now to reduce the current on the relay contacts his response was simple.... Waste of money, first off the relays are very expensive and by adding a second relay doesn't guarantee that it wont happen again at the extremely high speeds one may nanosecond release before the other and the flash over will occur again. I thank him for all his help, and offered to pay him for his time (being a service guy myself I know time is money and I was more then happy to pay for that time) he replied that is not necessary enjoy the amp and if you have any further problems with it ship it to me and I'll gladly address it for you. 73...
Okay, now I'm off the phone and begin to think, sleep, think, sleep, think they has got to be away to keep this from happening without having to send this back to Ray I need to do this on my own... Bang, the light comes on; my Yaesu FT1000MP Mark 5 has a DATA plug that is an 8 pin DATA plug that offers BAND DATA and XMIT DATA for use with the Yaesu QUADRA Amplifier. On this DATA PLUG is pin 3 which goes to GROUND when TRANMIT HAS BEEN triggered (NO RF YET) just as xmit has been initiated. Then there is the PIN 8 which is looking for a GROUND BACK to acknowledge that is it now OK TO TRANSMIT RF.. (This sequence happens very rapidly, its referred to as a HANDSHAKE) that allows the radio to coordinate its RF OUT ENERGY with a sequencing event that may have to take place IE, TRIGGERING A AMP, or STEPPING A AUTOMATIC TUNER, or SWR VERIFICATION the possibilities are endless. In my case, it was excellent choice to coordinate the keying sequence with the QRO for full QSK operations oh and the best part of this is that the rise and fall time is fully adjustable from the menu on the Mark 5.
Okay, my mind is running full speed now, I designed a circuit that looks at the ground signal from Pin 3 from the DATAPLUG and this ground then triggers 2 each MOSFETS which can handle upwards of 100 Volts @ 6 amps easily. When pin #3 on the dataplug goes to ground it fires the GATE signals on the MOSFETS which then triggers the XMIT GRD signal to the AMP's vacuum relay circuit. Interesting is now I need a feedback to the rig to acknowledge the amp has been triggered. Bingo, this comes from the GREEN LED on the front of the QRO amp, the relay which drives this GREEN LED lamp Opens and Closes 12 VDC to the lamp circuit board for just that purpose, I installed a small 12 VDC double pole relay on my circuit board and drive that relay with the same 12 VDC which drives the GREEN LED (xmit lite) on the amp from the small relay on the LV/BIAS circuit board (which by the way is the same relay that sends the FIRE command to the vacuum relay). Now I have a feed back signal, simply use one of the normally open contacts on my relay to trigger a Ground OUTPUT to the mark 5 telling it that the Vacuum relay has been trigger and RF is okay to fly. This all works fine and dandy when you’re ONLINE with the amp, but when in STANDBY mode the mark 5 wouldn't see the GROUND because the vacuum relay wouldn't be used as the amp would be in standby doing nothing... Solution, Yep Ray thought of everything when he built this amp, he installed a double pole, switch for the Operate and Standby mode switch, the second set of poles on this switch is empty and has a Normally Open and Close contact, simply run two wires from this switch to my Ground OUTPUT to the Mark 5 and the amp would then provide a GROUND OUTPUT to the mark 5 at all times if the amp were off or in STANDBY MODE. I installed 2 RCA jacks on the back of my QRO that are labeled QSK LOOP INPUT and QSK LOOP OUTPUT which will work with any other QSK rig that has this capability.
How does it work, it totally ROCKS, this amp will hammer at 80+ wpm at full QSK without missing a step. Flash over? What the hell is that, it don't exist anymore the sequencing controls all the signals back and forth to and from the rig and amp so each knows the exact state of the other at all times preventing the flash over crap.
What does this all mean...
#1... The drawings and schematics are so detailed I was able to build and design this circuit myself within a couple of hours and had it installed and running without any conversation what so ever with Ray @ QRO as a matter of fact, he doesn't even know I made this mod until he reads this...
#2... Hands down, this is by far the best amp I've ever owned in 36 yrs of contesting, rag chewing and chasing dx...
Conclusion??? SEE YOU IN THE PILEUPS; ILL BE THE ONE THAT GOT'M WHILE YOU’RE PLAYING WITH YOUR VOX RELAYS...
Simply put, BUY THIS AMP YOU WON'T REGRET IT!
73 - K0RU - Rob (old call - W8YRB)
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N4ZKF
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Rating: 5/5
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Dec 17, 2006 14:39
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Flawless
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Time owned: 3 to 6 months
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This amp is built with the word overkill in mind.
Bulletproof. I lost a balun one day running legal limit and it just tripped the circuit. I replaced the balun, fired it back up and went on with my business. I drive it with 45 watts on my FT-2000 and I love it!
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K5JAX
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Rating: 5/5
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Dec 3, 2006 10:40
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QRO is top quality
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Time owned: 0 to 3 months
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I have just had my amplifier for a few weeks. I have been a ham since 1960 and built big amps back then. The right components and design knowledge are key to making a good product. I looked at most all of the big tube amps and the new transistor ones from Japan. I decided that you couldn't beat the quality for your dollar with the QRO 2500DX. It loafs at about 800w PEP out and you hardly see the needles move at that power level. I have had it up to the legal limit, but I don't need that for ragchewing on 40m. It interfaces perfectly with my Kenwood TS-850SAT. Both final keying and ALC work well. Bird used for power monitoring. Distortion products are lower (probably TVI also) when you don't need to run everything at the max power out. More after a year of operation. 73's Roger
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WA8EBM
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Rating: 5/5
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Nov 10, 2006 09:55
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Solid no compromise high power
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Time owned: more than 12 months
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Owned it just over 2 years. Loafs at 1.5KW with low drive. I can drive it with about 12 watts out of my K2 and get about 750W- sometimes more out of the amp. Solidly built and when you turn the bandswitch you know it's heavy duty.
Just a couple days after 2 years it blew a fuse. Got with QRO and narrowed it down to a bad Russian tube socket on one of the GU74's. Mailed it back to QRO and they were kind enough to repair it under warranty. Had it back up and running in just over a week. No complaints there!
A few people have mentioned that the fan was quiet. I wouldn't really say that. It has to be noisy to circulate 1500 watts of heat around the tubes and plenums. There is a low/high switch for the fan. I use headsets most of the time when the amp is on. I have pulled the fan out of the amp and found the sleeve bearings to be dried out and oiled them and quieted it down considerably. I also remounted the fan on some high density 1/8 inch foam gasket. The blower is a standard Dayton available at Graybar. Tried to find a ball bearing fan that would fit but this is the best available. One note is that the T/R relay has some SWR smoothing caps across it in the de-energized position for direct transceiver feed thru. I found I could not pass a six meter signal through the relay. I have 6 meters on my PRO3 and FT2000 and you need to put the antenna for 6 on your alternate antenna output or in my case with the SteppIR that covers 6 meters, put in a switch to bypass the amp totally on 6.. I looked at all the tube amps, Acom, Alpha and other lower priced units and chose the QRO because of the oversized transformers and plate circuit components. The design has proven itself solid and I have found nearby customer service to be a big decision swayer. I also have a Icom PW-1 solid state KW Amp that I use with my PRO3 but I feel most comfortable with the QRO for brute force high power key-down service.
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K0CWO
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Rating: 5/5
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Jul 18, 2006 19:21
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Follow up
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Time owned: 6 to 12 months
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It has almost been a year with this amp in the shack. I run it at 1200 watts on the lower bands just about every evening. Operation has been flawless. If I had to buy another amplifier again, it would be this one.
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