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write your own review of the Svetlana 4CX800A ceramic tetrode.
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K7ORK
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Rating: 5/5
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Jan 7, 2009 10:51
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Nikmatvey for 91b replacement tubes
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Time owned: 0 to 3 months
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Alpha informed me that the AC trip problem with my 91b (purchased 1997) was caused by the GU74B (4CX800A) tubes going bad. I panicked when they could not recommend a source for replacement tubes.
After searching eBay for replacements, I ordered two tubes from Nikmatvey in Russia for $400 plus $30 for shipping. The tubes were not tested nor matched. They arrived about four weeks later.
The tubes were installed in less than fifteen minutes. They work great…less drive power to get full output.
Now, I don’t have to consider replacing the 91b because of lack of tubes.
ron@vinecom.co.uk is a source offering matched and tested GU74B tubes, but at a higher cost.
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DD4DA
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Rating: 5/5
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Jul 17, 2006 04:25
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GU74B Svetlana
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Time owned: 6 to 12 months
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I also work with the Russian Tube GU74B in my brand new PA called ALPIN100. This kinda PA needs also just 42 watts PEP to jump over the 1KW border. The differences between the tubes comes from Svetlana and Eimac is the operating temperatur they reached. My GU74B is manufracted in 06/1994 and after 2:30 min heating time (at startup of ALPIN100, the PA doesn't goes online til this time) the cool air of tube reaches 42C°. I also got a new EIMAC 3CX800A that manufracted in 11/1993. I replaced them and do the similar test with them. The results are similar in relation of input / output power but the differences are in the Temp of the cooling airstream temperatur. After Startup, the Tube Stream temp is at 31C°. In operation the Svetlana reaches the 75C° in just 30 Sec CW operation at 1Kw output. The EIMAC need more than 3 time longer an cool down in less than 1min to 35C°. This is not represently to seriusly compare that kinda tubes and if you got a well designed cooling system, that should never be a problem but demonstrate where the differences could be.
I prefer the cheaper variant and use the Svetlana. I payed € 75.- for a new GU74B at my PA dealer in the beginning of december 2005. My friend also purchaised an ALPIN100 and payed € 130.- for a replacement. Is't seems that the russian tube are getting not cheaper. I will pick up a secound one if i can get.
ACOM1000 is a nice AMP but the power supply is'nt well designed. That was the reason wy i does'nt got them and my choise was the ALPIN100.
vy 73 de Gerd, DD4DA
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G8LIK
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Rating: 5/5
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Jun 5, 2005 23:09
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These tubes rock!
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Time owned: more than 12 months
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As the proud owner of an Acom 1000 I can say the 4CX800A/GU-74B really delivers the goods without fuss, splatter or any other nasties at the 1KW power level. But have to wonder what will happen if/when the Svetlana NOS stocks dry up and you have to pay the full whack for those produced by SED. Some suppliers already charge over $200 for a single tube.Maybe a case of stock up now for rainy days whilst they are still around the $65 level on ebay?
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W5VYY
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Rating: 5/5
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Aug 3, 2004 17:56
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Great price
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Time owned: more than 12 months
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The Svetlana 4CX800A ceramic tetrode has a great power to price ratio. I just purchased two spare NOS tubes on ebay for $52 each for my QRO HF2500DX amplifier. What a bargain compared to the price of the 3-500Z, 3CX800, 8877 and other tubes built by Eimac. The 4CX800’s provide a power gain of 40X or 16dB on 160 and 80 meters where I do most of my operating. 40 watts of drive gives 1500 watts output and 65 watts of drive is an easy 2500 watts into a dummy load of course. I can not think of any tubes that provide high gain and high power at such an affordable price.
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WB9WHE
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Rating: 5/5
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Dec 21, 2002 23:07
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Dream come true!
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Time owned: 6 to 12 months
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At 20% of the price of a Eimac 3CX800A, the Svetlana product is just as good. While Eimac's product is shiney and very, very pretty, the Svetlana product is Russian millitary, butt-ugly. But at 1/5 the price of the Eimac tube, who cares!
Some thay that the Eimac has slightly better specs...kinda like saying there is a difference between 1400 and 1500 watts. IF there is a difference, you will NEVER be able to detect it, no matter how hard you try.
My tube is 1/5 the price of your Eimac ...and if you shop carefully, you can find Svetlana 4CX800a tubes at $55 street price, or about 1/10th the price of Eimac. I bought 4 as spares!
ETO and Alpha have already switched. Ameritron has not. Why? I have no idea. As for me, I'll follow Alpha's lead.
Dasvedanya!
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