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Reviews For: 572B Tubes- China Manu.

Category: Electron Tubes

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Review Summary For : 572B Tubes- China Manu.
Reviews: 27MSRP: $35
Description:
Watch Limited Warranty!
Product is in production
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00273.4
NZ0T Rating: 2009-05-29
Update Time Owned: more than 12 months.
An update to my review below of the Shuguang 572B tubes I got from Chen. My Al-811 started acting up with low power and grid current. Upon investigation I found one tube with a very loose cap that was inop and another with a somewhat loose cap and the 3rd was fine. I put my old 811As back in and the amp is fine now. These tubes were cheap and I got about 2 years of use out of them but I'm wondering if they are any better than good 811As now.
N3OQD Rating: 2009-03-23
30 second glowing plates? Time Owned: more than 12 months.
I have been running these tubes in my AL-811 for over a year with no problems. One thing that is puzzling about the previous post of the plates glowing in 30 seconds and this is supposedly the fault of the tube. The plate glowing is due to the amount of electrons ALLOWED to flow from the filament to the plate. It is the potential on the grid that controls this flow. The more negative the grid the more restricted the electrons are and the tube conducts less. The more positive the grid, the less restrictive it becomes thereby allowing heavier eletron flow to the plate. If the grid is exessivly positive than too much electrons flows. The thorium is then stripped from the filament (killing emission in short order) and the plate glows (overheats) quickly.
W8VVG Rating: 2009-01-08
Nothing but problems Time Owned: 6 to 12 months.
I also purchased a set of 4 572b tubes from jc368 and a back up set (8) tubes. The first set went soft in less than 3 weeks. I returned them and was told by Chen that I was over driving them (80watts) and would not honor the warranty. The second set is on the way out after 15 hours of use. I will make every attempt not to buy Chinese tubes again. Apparently my Dentron Clipperton L does not like them. The plates start to glow after about 30 seconds. I am running the Clipperton L in the low power position and about 600ma current. The original Centron tubes lasted 25 years with the same rig. I also found the tubes to be different lenghts
K1FU Rating: 2008-05-01
Shuguan 572B Quad Time Owned: 0 to 3 months.
Ordered from jcc368 on e-bay. First of all, these are not generic no name tubes. The visual inspection showed me a heavy duty anode and all internal components were top quality. Shipping and packing were first rate and you cant beat the price, $135 USD. 16 days from order to delivery. One problem, two of the tubes were slightly longer than the others. Chen told me if this were an issue he would resolve it, it was not. 1 year warranty will tell...
N2EYE Rating: 2008-01-27
Penta's great value Time Owned: more than 12 months.
I bought four matched Penta 572b tubes for a homebrew (my first). These tubes took some abuse in the fine tuning that was required to get amp (80-10) running. I run plate at 2600vdc under load and out put is great. I did have to return the tubes after delivery as my heaters are in-series and the resistance of one tube affected the voltaage districution untowardly. THat was no problem. I purchased directly from Penta got a good price and amp still goibng striong after 3 years. Also have an SB-201 with original Cetrons in it but what can you say when tuibesd are that old.?? neil ka2tus NYC
4X1PD Rating: 2007-12-18
No problems in 10 Months Time Owned: 6 to 12 months.
Ordered a matched quad set of 572B (Feb 2k7) on eBay (the seller - jcc368 ,directly from China, Hong Kong). Fast shipped (same day I ordered) and arrived in 12 days in perfect condition (very well packed- 7 layers). Graphite anode more thicker, unlike the thin metal of previous 811A.
The tubes have same power as the 811A at the same drive.
Total price: 120$ for all 4 include postage to Israel and they work in my homebrew PA, with grounded grid, until today (3 times knock on the wood ...).
Resume: no problems in 10 Months!
http://www.qrz.com/4z5nu
Greetings, 73 and good DX!
KG7TR Rating: 2006-09-10
One of two shorted Time Owned: 0 to 3 months.
I bought a matched pair of 572B's for my Heath SB-201 from a vendor in Florida. Price was $80. They arrived in less than a week, and were from the Shunguang factory in China. I powered up the amp on a variac with the plate caps off and everything seemed OK. When I put the plate caps on, I noticed the amp would draw idling plate current without the antenna relay line grounded. In fact, the relay was already closed. Some simple troubleshooting revealed one of the tubes was shorted from filament to grid. When I removed the tube and powered it up with just filament power from a bench supply, this was even more obvious. I could actually jumper the grid to one of the filament pins and the filament would glow brightly at the point of the short (only works on the filament pin closest to the short; the other pin had little effect). I called the vendor and they said send in the bad tube and they would replace it. They kept their word - and within a week I had a good tube. So I don’t have any problem with the vendor in this case. So far the tubes tune up fine; I will attempt to put them on the air today and see what happens. I believe one of the problems with these tubes is that there is very little spacing from the filament to the grid, so any defects in manufacturing or shocks during shipment could cause a short. As a suggestion, vendors that sell these tubes ought to consider screening them first by putting them into an amp to make sure there are no shorts. That would possibly save some time, frustration and postage for everybody.
W4HWD Rating: 2006-01-13
Same as below! Time Owned: 0 to 3 months.
Ordered 3 Penta Labs 572Bs from AES Cleveland. The day the tubes arrived I opened the amp up and dropped them in. Turned on the amp and the plate current meter indicated 150ma with *no* exciter input! Through process of elimination I found one of the three tubes to be shorted right out of the box! AES took the tube back but charged me for a replacement...they said they would credit me once the manufacturer says "yeah the tube is bad." We'll see how long it takes AES to credit me...but that's not the issue...like everything else made nowadays, you stand a better than average chance of getting a dud straight out the box. Too bad in this "global economy" nobody knows what Q.C. stands for anymore! Its a disturbing trend that's likely to get much worse before it gets better.
WD0CT Rating: 2005-07-24
3 new Pentas - one shorted Time Owned: 0 to 3 months.
I bought 3 new 572b for my AL811 from Penta Labs. Almost immediately one developed an intermintent grid to filament short.

This became a permanent short a couple weeks ago. I called up Penta and got an rma number and sent the tube back. A new tube arrived a couple days ago and the amp is running fine now.

I think that is good service and I would buy from Penta again.

Interestingly enough, the new tube is 3/16 to 1/4 inch shorter than the others. The date code of the originals is 0512 and the date code of the one new tube is 0514. So in two weeks time Penta's chinese supplier changed the tubes a bit.

The guts still look the same so I'm not worried about it.

The tubes have no more power than the 811a at the same drive as they use the same cathode. More drive equals more power though and I run the 572bs at 800ma with no problem.
WV4I Rating: 2004-12-25
Chinese Made 572B's Time Owned: 0 to 3 months.
Got mine from RF Parts, 2 for $70, not matched, no need per Ameritron. Grounded grid amp. No problems whatsoever. Mixed with two older, probably also Chinese tubes in AL-572 just fine.