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Author Topic: DX Engineering 572b tubes  (Read 35668 times)
K8AXW
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« Reply #30 on: January 31, 2016, 10:34:52 AM »

So now it would be interesting to poll those who would pay extra for Cetron quality vs. those who are willing to continue gambling on the Chinese tubes that are being made today.

(I might add, $200.00 per tube made by the Chinese, who seem to be the only tube makers) would be excessive considering their labor and even shipping costs....which basically is negligible.)
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W8JX
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« Reply #31 on: January 31, 2016, 11:42:17 AM »

So now it would be interesting to poll those who would pay extra for Cetron quality vs. those who are willing to continue gambling on the Chinese tubes that are being made today.

(I might add, $200.00 per tube made by the Chinese, who seem to be the only tube makers) would be excessive considering their labor and even shipping costs....which basically is negligible.)

I think it could be done fore 100 to 150 per tube "IF" importer would stop adding a very big markup. I would rather give 80 or 100 per tube direct from china for a good tube than same price stateside which has to use lower cost/quality tubes to sell at same price and make a profit. 

You have production in China to boost profit margins. Several years ago Pfaff sewing machine company of Germany bought out Huskvarna Viking sew machines that were made in Sweden and long known voer excellent quality. After purchase they liquidated inventory and closed factory in Sweden and moved production to China. They did not reduce cost of products but did boost profit margins and lower quality some for sake of profit. In the end it is all about profit and greed. Same reason ceramic power tubes still built in US are so expensive because one reseller has rights to most of them and will charge whatever market will bear.

There was a time when manufactures took pride in making a good product at a fair price but that has gone away today to greed and profit.
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N9AOP
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« Reply #32 on: January 31, 2016, 12:05:05 PM »

My wife has a Pfaff that was made in Germany and the quality of that one vs the current production is amazing.  Also, what shocked me is the Airlines.  They are passing on some of the lower fuel price savings on to the consumer.  That is totally contrary to the usual practice of shoving it into the stockholders pockets.

If the tube importers could be honest with us most wouldn't care.  If it takes 4 tubes to get one good one then we have to pay for the other three but if you don't know when you are being hosed, that's a problem.

Art
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W8JX
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« Reply #33 on: January 31, 2016, 12:21:45 PM »

My wife has a Pfaff that was made in Germany and the quality of that one vs the current production is amazing.

Huskvarna Vikings were same way before Pfaff bought them out and effectively killed them as a high quality item. Did they move Pfaff production to china?
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VK3BL
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« Reply #34 on: January 31, 2016, 07:15:42 PM »


If the tube importers could be honest with us most wouldn't care.  If it takes 4 tubes to get one good one then we have to pay for the other three but if you don't know when you are being hosed, that's a problem.

Art

And there in lies the problem.  Even if that was the case (and I really, really doubt it is), how good could that 4th tube possibly be?

If 75% of your production run fails, your product is either incredibly complex with demanding requirements (think high 4 GHz+ Speed computer processors with multiple cores that all need to meet that spec), or your manufacturing process is completely ****house.

Despite what some may like to claim, vacuum tubes are no where near as hard to manufacture as most of the consumer goods we see today.  Therefore, there are only two possibilities:

A) They do have a 50%+ defect rate, and as such the 50% that do work are likely to be ****house anyway or;
B) We are getting conned when we're told they have a high failure rate.

Either way, the product is terrible from a market perspective; it is either drastically over priced, or of considerably poor quality.

Given I know from first hand experience that the product shows defects only after 15+ TRANSMITTING hours, a certain retailers claims of high failure rates to justify high prices makes me nervous.  This is because I know that high failure rates indicates that even the products that pass will be of low quality, and that there is no viable way any distributor can 'test' the product for failures 15 hours down the track, no matter what they claim.

Either give us expensive tubes made using a quality production process, or cheap crap and let us absorb the failure rate.  Cheap crap at a high price that has been 'tested' is nothing more than a marketing gimmick.

Most of us would probably be better off converting 572B amps to use Russian GS-9B or GI-7BT tubes.  Not only are they cheap as chips, a good set will likely live longer than most of us.
« Last Edit: January 31, 2016, 07:18:25 PM by VK3HXT » Logged

J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
K8AXW
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« Reply #35 on: January 31, 2016, 07:28:25 PM »

Well, it's one thing to deal with junk but when the junk fails and takes expensive, and in some cases, unobtainium parts with them, then it is unacceptable.  But, if ya wanna play, ya gotta pay.  Greedy bastards!
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G3RZP
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« Reply #36 on: February 01, 2016, 03:28:22 AM »

I believe they may have problems in getting filament wire: there can't be a lot of demand out there for tungsten wire with around 10% thorium in it, and the carbon anodes need some work to produce. I suspect the real thing that pushes costs up is the time it takes to really pump the tube down after carburising the filament and then really baking the tube for some hours to get all the gas out - including heating the electrodes. Then to do the job properly, you would burn in the tubes for say 24 hours at rated output, probably in a self excited oscillator. Now that would cost in time, electricity and test fixtures, and so they probably try making them in a similar fashion to churning out 6CB6s!

Quote
There was a time when manufactures took pride in making a good product at a fair price but that has gone away today to greed and profit.

Partly because the way institutions like Wall Street are only interested in the last quarter's numbers. There are still a few small companies that take pride in producing value for money but they don't tend to be anything but small or very small.
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K4PDM
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« Reply #37 on: February 01, 2016, 03:33:09 AM »

If you look at a chinese site, they're less than half the price of any western retailers @ ~$32 USD.

The "$80/$89 USD" figure offered by stateside retailers is likely lining their pockets significantly given I'd expect they get them at a much better price direct from the manufacturers.  Maybe quality control really is as bad as they say, and for every two tubes they buy they can only sell one... but I doubt it very much.

The only reason 572Bs are so expensive is because we've been told that they are, and Ham's are desperate enough to pay it.

http://world.taobao.com/item/8272746462.htm?spm=a312a.7700714.0.0.wZ8Kuo#detail

That site lists the anode voltage spec at 1250V.
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W1QJ
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« Reply #38 on: February 01, 2016, 03:40:48 AM »

At 1250 that's about half or less than what we run them at.  For audio they ate probably fine but for RF that's a different ball game.
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VK3BL
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« Reply #39 on: February 01, 2016, 04:41:38 AM »

At 1250 that's about half or less than what we run them at.  For audio they ate probably fine but for RF that's a different ball game.

At 1250v would appear to be Shuguang's official rating for their 572B product.

I don't have an answer to that one.  Perhaps stateside retails have arrangements to get the 'cream of the crop', and pay extra.  Maybe they buy a truckload of them and find a few that pass hi pot tests at RF voltages.

I can't answer that one, however it adds more weight to my point that the current 572Bs are not a great product from a market perspective.
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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
W1QJ
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« Reply #40 on: February 01, 2016, 05:19:56 AM »

At 1250 that's about half or less than what we run them at.  For audio they ate probably fine but for RF that's a different ball game.

At 1250v would appear to be Shuguang's official rating for their 572B product.

I don't have an answer to that one.  Perhaps stateside retails have arrangements to get the 'cream of the crop', and pay extra.  Maybe they buy a truckload of them and find a few that pass hi pot tests at RF voltages.

I can't answer that one, however it adds more weight to my point that the current 572Bs are not a great product from a market perspective.

I haven't heard much about the "new and improved" units that RF Parts has been sending out lately.  They sure look alot different than anything else on the market and therefore easily spotted as "different".  I suppose it is too early to tell.  What tubes have been being sent out in new Al-572 amps?   I am sure that Ameritron will want the "new and improved" version but it seems that they are exclusive to RF Parts.  If so, they won't get them. of course like earlier mentioned we could buy a whole load of them at $32.00 direct from China with about $12 shipping on a pair of them.  We should form a CO-OP and buy a hundred or so, have them shipped to one place and distribute them in flat rate boxes or first class mail.  I wouldn't mind taking on the project with the understanding that bad tubes will be tough luck.  But since they are about 1/3 the price you can get just about 3 for the price of one.  You will be ahead of the game if you get lucky and your tubes are good.  We take worse chances buying lottery tickets.
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VK3BL
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« Reply #41 on: February 01, 2016, 05:28:46 AM »

I haven't heard much about the "new and improved" units that RF Parts has been sending out lately.  They sure look alot different than anything else on the market and therefore easily spotted as "different".  I suppose it is too early to tell.  What tubes have been being sent out in new Al-572 amps?   I am sure that Ameritron will want the "new and improved" version but it seems that they are exclusive to RF Parts.  If so, they won't get them. of course like earlier mentioned we could buy a whole load of them at $32.00 direct from China with about $12 shipping on a pair of them.  We should form a CO-OP and buy a hundred or so, have them shipped to one place and distribute them in flat rate boxes or first class mail.  I wouldn't mind taking on the project with the understanding that bad tubes will be tough luck.  But since they are about 1/3 the price you can get just about 3 for the price of one.  You will be ahead of the game if you get lucky and your tubes are good.  We take worse chances buying lottery tickets.

Yup I agree.  I'd be interested in being in that lottery. 

The trick will be finding a decent Chinese supplier, and I think that may be a bit of work sending emails and what not, but it is definitely something that would benefit a lot of people.

At 100 or so units purchasing from Shuguang or a larger distributor might even be an option.

I think the main reason companies don't offer that sort of arrangement is that consumer law prevents them from saying 'these tubes are cheap, but you get no warranty'.  I feel for them in that regard, and do understand the need to up the price.  Its just the warranty is worthless to us VKs anyway, so I don't want to pay 2/3rd extra for it.
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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
W1QJ
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« Reply #42 on: February 01, 2016, 06:07:53 AM »

Did you check out that link?  They can be bought from them directly.  Looks like they take  MC Visa. Should be no problem.  Website does language translation.
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W8JX
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« Reply #43 on: February 01, 2016, 06:45:28 AM »

The main problem with 572's is gas and it comes from graphite anode which tends to trap air when made and it leaches out over time as anode heats and cools. More time/care needs to be taken with heating anodes in a vacuum being applied to get gasses out of it but time is money and lost production so corners are cut. I was told by RF parts at hamvention that they were beating and pulling vacuum on new 572's before being sealed. Time will tell.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
G3RZP
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« Reply #44 on: February 01, 2016, 08:43:07 AM »

I remember reading that one U S manufacturer ran 6AQ5s with a red hot plate for about an hour while pumping down to get the gas out - and that's a small metal plate! Carbon plates I suspect need running red hot for probably two or three hours or more to thoroughly de-gas them.
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