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Author Topic: DX Engineering 572b tubes  (Read 36012 times)
W8JX
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« Reply #45 on: February 01, 2016, 11:11:24 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.

RF parts guy said they were doing 24 hrs..... Also when you draw a vacuum with any plate glowing it expands what air is in there and helps vacuum...
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Ham since 1969....  Old School 20wpm REAL Extra Class..
KD0REQ
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« Reply #46 on: February 01, 2016, 12:34:33 PM »

pretty much all the tube manufacturers used induction heating near the end of the production line to help degas the product, including receiving tubes.
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KD0REQ
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« Reply #47 on: February 01, 2016, 12:38:07 PM »

  The new RF Parts 572B tubes definitely look much different than what DXE is selling and these from China.  Tge ones at the site look like the old ones that were coming over.  If you read the specs on these tubes at the site all the ratings are given at a anode voltage of 1250v.....

which proves they are made for audiophools.  Cetron specced max plate voltage at 2750.
http://www.crompton.com/hamradio/heath/sb200/cetron_572bt160l.pdf
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KM1H
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« Reply #48 on: February 01, 2016, 05:15:09 PM »


which proves they are made for audiophools.  Cetron specced max plate voltage at 2750.
http://www.crompton.com/hamradio/heath/sb200/cetron_572bt160l.pdf

And they are also rated 1650V Plate modulated Class C which tells you there is a lot of voltage breakdown overhead and 2750V SSB isnt even close to pushing it.

Carl
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VK3BL
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« Reply #49 on: February 01, 2016, 08:35:12 PM »

Just out of interest, what is the different look that the RF Parts tubes have?

Sure, they have a ceramic base... but other than that the internals look the same, don't they?  Am I missing something?

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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
VK3BL
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« Reply #50 on: February 01, 2016, 08:36:50 PM »

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.

Yeah I posted the original one to taobao.  The main problem is I'm not sure how well they speak English, and whether or not they will be able to supply in that quantity.

Taobao is more like Alibaba, in that you need to negotiate a deal.  Its not like aliexpress or ebay where you can just click buy.

At least that is my understanding.
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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
K4PDM
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« Reply #51 on: February 02, 2016, 03:02:17 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'm pretty sure the AL-572 has been discontinued. The three dealers I checked no longer list it.
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W8JX
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« Reply #52 on: February 02, 2016, 03:08:53 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'm pretty sure the AL-572 has been discontinued. The three dealers I checked no longer list it.

When I spoke to Amertron rep at Hamvention they said that AL 572 production was on hold until a reliable supply of tubes could be found and that it was not going to use RF parts for a source for cost reasons.
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MM0IMC
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« Reply #53 on: February 02, 2016, 03:37:43 AM »

When I spoke to Amertron rep at Hamvention they said that AL 572 production was on hold until a reliable supply of tubes could be found and that it was not going to use RF parts for a source for cost reasons.

Is that because it's built down to a price and not up to a standard? Huh
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VK3BL
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« Reply #54 on: February 02, 2016, 04:28:33 AM »

When I spoke to Amertron rep at Hamvention they said that AL 572 production was on hold until a reliable supply of tubes could be found and that it was not going to use RF parts for a source for cost reasons.

Is that because it's built down to a price and not up to a standard? Huh

The AL-572 only makes sense as a 'cheap near kw' amp (thats its whole market angle), and $320 USD worth of crappy tubes that last at most a few years doesn't exactly make it a cheap amp any more.

Even if the tubes are decent, $320 isn't cheap - that's in the single ceramic tube region, and they by and large, are decent.

Heaven forbid if they made 572Bs any more expensive...
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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
W8JX
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« Reply #55 on: February 02, 2016, 05:40:22 AM »

When I spoke to Amertron rep at Hamvention they said that AL 572 production was on hold until a reliable supply of tubes could be found and that it was not going to use RF parts for a source for cost reasons.

Is that because it's built down to a price and not up to a standard? Huh

The AL-572 only makes sense as a 'cheap near kw' amp (thats its whole market angle), and $320 USD worth of crappy tubes that last at most a few years doesn't exactly make it a cheap amp any more.

Even if the tubes are decent, $320 isn't cheap - that's in the single ceramic tube region, and they by and large, are decent.

Heaven forbid if they made 572Bs any more expensive...


Four decent 572's are far more rugged than a single 3cx800. Pretty much impossible to over drive or damage tuning. I have a old Dentron Clipperton QRO and with four 30 year old Cetrons and it will still make 1200 plus watts out with little effort. I usually run about 850 to 900 watts out with 50 watts drive.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
W1QJ
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« Reply #56 on: February 02, 2016, 05:43:37 AM »

I haven't seen one of the new RF Parts "new and improved" type 572B tubes.  Someone who has said that the base is ceramic and white and the pins are gold colored.  I heard the glass tube envelope is a different shape.  There may be some slight internal structure differences.  Suffice to say however that the newer tubes can easily be identified from the older style we are used to.  The DXE tubes have that same "tag" on the base that I see on the photo at Taobao site.  With the ability to buy tubes at $32.00 each and sell them for $89.95 it is easy to see that buying up a batch of 500 for a dealer is a no brainer.  I would also venture to say that if you are doing that kind of volume you can send your duds back twice a year to the MFG'er and get credit on your next shipment.  Regardless of what you think of the Chinese, my dealings with them as business people is very favorable.  I would not expect them to have you suck wind on duds.  The question is still lingering however.  The question is this.  Are the "new and improved" RF Parts 572B tubes that "look different" an EXCLUSIVE offering by RF Parts and no one else?  Are the tubes really better or is it just smoke and mirrors to try and regain confidence in buyers who think a better product is under a new look?  I don't know the answer and perhaps only time will tell.
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W8JX
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« Reply #57 on: February 02, 2016, 07:36:23 AM »

I have seen and handled tube and while appearances can be deceiving, it looks and feels like a quality product. It does have a white base and gold pins but envelope is basically same as Cetron from pictures I took.  When I talked to them at Hamvention they made it clear that they had exclusive rights to tubes made this way and were not going to be selling them whole-sale to other vendor to repackage and resell.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
KM4AH
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« Reply #58 on: February 02, 2016, 07:44:20 AM »

Seems to me that RF Parts has put a bit of effort in to getting a reliable 572 B produced. I hope they make some money at it.
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N9AOP
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« Reply #59 on: February 02, 2016, 09:00:32 AM »

Getting the tubes for $32 and selling them for $90 is as American as apple pie.
Art
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