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Author Topic: New QRO 8877  (Read 12403 times)
K0CWO
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Posts: 416




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« Reply #15 on: August 03, 2012, 02:14:07 PM »

I am sure about 4150 idle plate voltage.  Two HF-2000's I know measure that.  I know what the manual says.  How do you get 1500 watts out of 2700 volts and 800 mills?  Unless the amp is 70% efficient the math does not add up.  Again, lots of things in some manuals don't add up.  Besides, I think Ray will tell you that 4150 volts is pretty close.

73, k0cwo
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W8JX
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Posts: 5487




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« Reply #16 on: August 03, 2012, 02:54:33 PM »

Are you sure about that 4150v idle plate current?  Are you sure it's not 3150 and 2700 you mean.?

3-500's "play" better with higher plate voltage. 4KV or so idle is not excessive and while those tubes are not known for high gain they do better with higher voltages.
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QRPNEW
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Posts: 51




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« Reply #17 on: August 03, 2012, 06:31:46 PM »

Looks like a nice amplifier. Why did they not use a band switch that allows for the WARC bands?

  Sure you can tune the WARC bands using other bandswitch positions but this is a primitive way of doing things. The power limit
on 30 meters only applies in  the USA and nowhere else in the world. Why make the amplifier unattractive  for international users?
The Alpha 89 had every WARC band covered by a switch position and thats why I love the Alpha 89.

This amplifier  just seems to be a new amplifier using the old QRO model recycled parts. The competing amplifiers from Acom, OMPOWER and Emtron all have the WARC  bands covered with a switch position.

These comments apply to the Ameritron range of amplifiers as well, they really old designs that need to be updated. This reminds me a lot about the Japanese VS detroit automobile debate. The Japanese are winning the war
because they offer good value and deliver features  and luxuries that people actually want. All we get from Detroit is nothing more than John Deere tractors!

While we dont need bells and whistles on amplifiers, we need good attention payed to the basic design, and that would include WARC position on the bandswitch.

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K0CWO
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Posts: 416




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« Reply #18 on: August 03, 2012, 09:51:50 PM »

Although we don't know the specifics yet, I noticed the omission of the WARC bands as well.  With the exception of the 30 meter band, the QRO HF-2000 includes 17&12 meters which is a nice feature.  Not being an engineer nor marketer I suspect a free market savvy individual finds a niche.  I have no idea what the additional cost of 30, 17&12 would be, but I'm sure that comes to play.  Compared to the HF-2500 and HF-2000, the new HF-3KDX looks like a much friendlier amplifier to repair, if needed.  I've never used an amplifier on 30 meters and the times I've used an amplifier on 17 or 12, I can count on one hand.  I guess Ray is marketing this amplifier to a guy like me.  Wish I had the bux to splurge.  In the mean time, my 5 year old "Chevy AL-1500" does the job just fine for casual SSB rag chewing.  The QRO HF-2000 I own is a winner too.

I sure do like to see the selection of quality parts that go into this amp.  Like anything I've seen from QRO, that design philosophy hasn't changed. It is a plus when it comes to bang for the buck customers.  BTW, I have no connection to Ray.

73, k0cwo   
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G3RZP
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« Reply #19 on: August 03, 2012, 10:02:06 PM »

I suspect that there's no interest in export. Fusing both sides of the mains is a 'no-no' for Europe.
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KU7I
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Posts: 122




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« Reply #20 on: August 04, 2012, 05:25:12 AM »

My L-4 had a custom outboard PS that ran 4000 vdc at idle and dipped down to around 3700 fully loaded. 1500 watts out all bands was never a problem....man that was a beautifully built amp. Sure miss doing business with Peter Dahl. When I worked at White Sands in New Mexico in the early 90's I must have bought a half dozen xmfrs new from him and would drive an hour to El Paso to pick them up.....the first thing you noticed that let you know you were there was the large HF beams he had installed at his work shop. Lane
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W1QJ
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Posts: 1443




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« Reply #21 on: August 04, 2012, 05:52:56 AM »

"The dual 3-500ZG amp doesn`t deliver full output in cw no matter how hard you drive it."

What dual 3-500ZG amp are you referring to?

I have a QRO HF-2000 with RF Parts 3-500ZG's in it that are two years old.  The following is what I get on 40 meters (7.2 MHz) driving the HF-2000 with 95 watts RTTY/CW from a Yaesu FT-950 into a Palstar DL2K dummy load:


4150 plate volts at idle

3750 plate volts under load (95 watts of RTTY/CW drive).  That produces 800 mills of plate current (3750 X .8 = 3000 watts input).

Seems to deliver full output to me using a 50% efficiency figure.


I don't have any lab accurate watt meters here but my Palstar AT5K and Ameritron AWM-35 certainly indicate 1500 watts out with the above scenario.

For what it is worth.

73, k0cwo     


The manual for this amp indicates normal operating Hv to be 2700 to 3200.  Your 4150 is a far cry from those numbers.  Perhaps your metering resistors or meter are not reading correctly  The HV meter scale only goes up to 3500v full scale anyhow.  So how is this possible?  Also the 8 ps caps wouldn't support that high voltage for very long.  Something isn't right.
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W8JX
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Posts: 5487




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« Reply #22 on: August 04, 2012, 08:09:26 AM »

The manual for this amp indicates normal operating Hv to be 2700 to 3200.  Your 4150 is a far cry from those numbers.  Perhaps your metering resistors or meter are not reading correctly  The HV meter scale only goes up to 3500v full scale anyhow.  So how is this possible?  Also the 8 ps caps wouldn't support that high voltage for very long.  Something isn't right.

You did your homework on this and something is not right indeed. The math does not add up.
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N3JBH
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« Reply #23 on: August 04, 2012, 09:50:55 AM »

Quote
The Japanese are winning the war
because they offer good value and deliver features  and luxuries that people actually want. All we get from Detroit is nothing more than John Deere tractors!

I happen to like John Deere Tractors and many of them under 100 HP are or where made in Japan after the mid 1980's
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W8JX
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Posts: 5487




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« Reply #24 on: August 04, 2012, 09:55:12 AM »

Quote
The Japanese are winning the war
because they offer good value and deliver features  and luxuries that people actually want. All we get from Detroit is nothing more than John Deere tractors!

I happen to like John Deere Tractors and many of them under 100 HP are or where made in Japan after the mid 1980's


Actually if Detroit had built the old "John Deere tractors" of cars Japan would not of got its foot in the door.  Instead they let Japan built them and take over market.
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NO2A
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Posts: 758




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« Reply #25 on: August 04, 2012, 12:33:25 PM »

I was referring to their website specs for the HF-2000. If you click on that you will clearly see they state the power output for this amp on cw is 1200. I don`t know what the manual says.
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K6AER
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Posts: 3488




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« Reply #26 on: August 07, 2012, 02:16:54 PM »

A few things pop into the mind upon looking at the new product but cannot be confirmed without posted specifications.

The 8877 will need about 3500 volts to really come to life. 4000 is even better.

It has been my experience that the QRO designs share little with the Pat Stein work from 20 years ago. Anyone who has had to work on a Commander amplifier will attest to that and is why Ray and Pat split up over the ownership of Commander.

The blower on the inside will be nosier for an 8877 requires about .7 inches of water pressure for sufficient cooling. I noticed it is larger than the old unit.

The Alpha 8410 noise level is 52 dBa at 12 inches in front. I wonder what the new unit’s noise level is.

The E core transformer looks a bit small. Don't expect a lot of key down RF reserve. The amplifier should have at least 2 dB on SSB but I expect the CW RTTY performance will have little headroom.

I see Ray is using a 4:1 balun in the output to minimize the output load capacitor. Harmonics will be attenuated a bit less.

The 160 meter operation has a toroid in series with the tank coil. 160 output will be a bit reduced.

Over all it looks like a nice progression for I expect the GU-74B’s QRO has been using, are really getting hard to get. This is why Alpha came out with the 8410 three years ago. The Chinese produce very good 8877’s for about $500 and change. I think this is a good engineering decision.

It would appear Ray has a winner on his hands.
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KE2TR
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Posts: 130




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« Reply #27 on: August 07, 2012, 02:58:16 PM »

Some of you need to get new glasses, if you look at the rear panel shot there looks to me as there is a tuned input for every band, the caps for the PS can be seen on the side veiw pic as well, underneath the diode strings. Boy you guys gotta look closer at those pics, your all kinda ruff on this guy. His amp are very well designed and not some noise boxes like the comanders were, he seems to use well designed blowers with smooth bering race in his amp's. BTW the Dentron DTR2000 used an 8877 and had no tuned input, just a small toroid if I rememeber right and the 77DX/SX had a swiths by the tube that would let you go directly into the tube which was around 54 ohms that would bypass the tuned input for use on other parts of the spectrum removed a little away from the ham bands for MARS. As far as the band switch I bet my bottom dollar that its the kind that snaps into position not some girly band switch that feels week and as far as the warc bands go you cant runn more than 200W on 30mtrs and 17&12 are close enought to use 20&15 mtr taps, my call would be to give tha ham op's a REAL BANDSWITCH and that one in the pic doesnt look girly to me. I would like to know how many of you guys that are throwing stones and being BB on this new amp even ever built a home brew 8877 plus Alpha has been using toriods in there tanks for a looonnnggg time.
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N4RSS
Member

Posts: 258




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« Reply #28 on: August 07, 2012, 07:06:36 PM »

Some of you need to get new glasses, if you look at the rear panel shot there looks to me as there is a tuned input for every band, the caps for the PS can be seen on the side veiw pic as well, underneath the diode strings. Boy you guys gotta look closer at those pics, your all kinda ruff on this guy. His amp are very well designed and not some noise boxes like the comanders were, he seems to use well designed blowers with smooth bering race in his amp's. BTW the Dentron DTR2000 used an 8877 and had no tuned input, just a small toroid if I rememeber right and the 77DX/SX had a swiths by the tube that would let you go directly into the tube which was around 54 ohms that would bypass the tuned input for use on other parts of the spectrum removed a little away from the ham bands for MARS. As far as the band switch I bet my bottom dollar that its the kind that snaps into position not some girly band switch that feels week and as far as the warc bands go you cant runn more than 200W on 30mtrs and
17&12 are close enought to use 20&15 mtr taps, my call would be to give tha ham op's aREAL BANDSWITCH and that one in the pic doesnt look girly to me. I would like to know how many of you guys that are throwing stones and being BB on this new amp even ever built a home brew 8877 plus Alpha has been using toriods in there tanks for a looonnnggg time.

What are you babbling about ? None of the posts belittle the amplifier. Also, do us all a favor and brush up on your spelling
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KE2TR
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Posts: 130




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« Reply #29 on: August 07, 2012, 11:42:44 PM »

Oh another friggin english major but do you really read the posts or spell check them, there were a few posts that seem to belittle the QRO amps. I my self have owned two of his amps in the past, they were in the same ball park as the alpha's, very well made, not cheap and help up well under contest conditions, I also owned a 77DX and that was a sweet amp but really needs a bigger xfmr to play well, had a AL1500 and for what they sell for was one very nice amp but its no 77Dx, the Dentron 2000 I worked on for a buddy, it was crap so was the MLA2500 but if you run those amps at 1200W output they will hold together, at 1500W during a contest weekend they will break.
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