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Reviews For: FU-728F TETRODE TUBE

Category: Electron Tubes

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Review Summary For : FU-728F TETRODE TUBE
Reviews: 6MSRP: $200usd
Description:
FU728F Chinese TUBE Equivalent to 4XC1500B. More Robust With Heat Dissipation 1600Watt.
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0064.2
QRPNEW Rating: 2019-12-13
Poor quality and long term reliability Time Owned: more than 12 months.
While I was also a believer in the hype regarding these tubes. The 1st tube that I had that I bought with the AMP lasted 1 year. Then i had a real battle finding good spares. I tried the Ebay route and all the tubes are gassy or failed rejects. I ordered 6 tubes from different supplies all were gassy and arced over. I did follow all the procedures to condition the tubes, including running the filaments with grid bias and heater voltages for 1 week. Same result tube arced over. I went from Ebay to Ali-express with sellers offering a guarantee for 60 days same thing tubes flashed over in less than 1 month of intermittent use. Then I bought 2 x tubes from OMpower at great expense. These tubes were supposed to be conditioned and tested.and over 4 months of rotation and intermittent usage they failed as well. Either i am jinxed or the tubes are really crap. The end result is that I have been unable to find a trusted and realiable source for these tubes. The prices have also gone through the roof and for such an unrealible tube its becoming a real rip off. I had my Dentron MLA2500 with the same pair of 8875's for 25 years. I still have by TL922A with Eimac orginal tubes still going strong at 1200 watts output with no faults. I have a homebrew 6 metre amp with 4cx250b's thats more than 30 years old with the same tubes that has been through hundreds of contests and the tubes are all good. From this perspective you can see how crap the FU728F's really are.

By the time I am done paying all the returned postage costs I could have bought another pair of 3-500's that would have lasted 20 years.

My advice is while the current factory tubes are so crap I would not buy any amp that uses these tubes. They seem to be going up to extreme prices and for these extreme prices they cant offer you a reliable tube which will last more than 1 year! I know my amp is good because my buddy has a 2 holer with good tubes which I have tried in my amp. My next step is to try and buy a tube from Array Solutions and see if the quality is the same crap that lasts for less than 1 year. These tubes are popping like fuses within a year and the sellers have no control over the quality.

Its become a rip off buying FU728's. Its shame since the current amps that are on the market are very good and will outlast us all but unfortunately the tubes are crap. If you like changing tubes like light globes and have the money buy a FU728F amp otherwise avoid at all costs. I am now going solid state or considering buying a 8877 amp or maybe even a reliable solid state amp. Yes I am very frustrated since I have been very patient with gettering/conditioning these tubes in a specially made jig with socket, heater and bias voltages with the fan running. Even with this special treatment the tubes are turning to crap AVOID AT ALL COSTS. When some manufacturer offers a 1 or 2 year warranty on these I might change my opinion but at the moment whoever it is who is selling these tubes is selling the same crap that you can buy directly from China if you are willing buy 10 to 15 duds from the factory. If anyone can recommend someone who sells these tubes I would be willing to try them but for now I have a useless amp with no tube.

Further update. I tried to get a refund through Aliexpress after lodging a refund. They then asked for things like "provide pictures of the part mounted on the vehicle" Then they said "show pictures and close ups of the fault" " The seller rejected your claim" despite offering a warranty and 30 days refund. Not only that the refund fund amount that they are refunding is less double the shipping price I paid for shipping.

Avoid the crooked behavior of Aliexpress that defends the crooks with such ridiculous requests. Their language skills are very poor and you stand no chance of getting your money back. if they do refund I will update further. But it looks like the junk tube sellers and Aliexpress work together to protect these crooks. Do not under any circumstance buy a FU728F on any Auction site or places like AlixExpress.
W5RG Rating: 2017-08-03
GREAT POWER Time Owned: 6 to 12 months.
I have a pair of these tubes in a chinese amplifier.I see 6KW out of the pair.The amplifier works very good with very low drive. Be careful where you buy spare tubes..I have a friend VE2ZV that has the same amplifier and bought spare tubes from e-bay and has problems now with the amplifier. He has lost idling current and is now in need of repair..Safe to say never buy cheap tubes on e-bay..He did get his money back.. that's a good thing. These tubes have gone up in price and will keep going up.I bought a extra set when I bought my Amptec LA4000. Glad I did!
AB4D Rating: 2016-09-10
4CX1500B on Steroids Time Owned: 6 to 12 months.
I have a pair of the FU-728-F tubes in an OM Power 4000A amplifier. The tubes seem very rugged and the amplification factor is excellent. I've seen a pair of these tube make over 6200 watts, without any issues.

I found nothing to complain about regarding these tubes.

NN2X Rating: 2016-09-04
Great Power Time Owned: more than 12 months.
I have the DX 3SP (Emtron Amplifier) which uses two FU728F's. The Output is higher than the 4CX1500B at a fraction of the price.

With my Emtron, I can generate 5,000 (Watts) PEP.

If the tube fails (One of them), I can use just one of the tubes, and easily obtain 2500 Watts (Nice feature from Emtron)...

The Tubes can be as low as 200 (USD), sometimes, 400 (USD)...Bottom line less expensive more power, and available


ZL4IV Rating: 2016-09-03
Value for money Time Owned: more than 12 months.
My two amps use the FU728F's, DX-2sp & DX-3sp. Output is much greater than the 4CX1500B at less cost. The Emtron amps will take these though as heater voltage tap is provided but output will be down by about 25%. There are 3 types of FU728F's, easy to know what version to buy, lots of information about them. Current production (2016) are robust and reliable, the others, take your chances.
VK6WB Rating: 2015-01-14
VERY GOOD Time Owned: 0 to 3 months.
Just bough this tube from BD3MO, for $200usd.its 100% full spec and stable. My AMP is EMTRON DX-1SP
So now I use the original tube that come with the AMP as Spare. Don't buy from E-bay you might get
dodge one hi.