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Author Topic: 3CX1500A7 -vs- 3CPX1500A7 (8877 Tubes)  (Read 28603 times)
K2FX
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Posts: 20




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« on: September 06, 2012, 05:29:14 AM »

Lately I've noticed that the cost of 8877's has really been climbing, especially the Eimac variety at over $1200-1800 each! Recently a friend turned me on to an alternative, which is the 3CPX1500A7.  The only difference is that it's marketed as a commercial tube that is also pulse rated.  Basically it looks exactly like the original 8877 in most specs and physical appearance, but the cost is WAY LESS!  Has anyone had experience or success using this tube as a replacement to the standard 8877?  I am looking for back-up tubes for my new Henry 3K Ultra Amplifier.  At about $250.00 each, the savings would be significant.

Paul, K2FX
« Last Edit: September 06, 2012, 06:20:19 AM by K2FX » Logged
W1QJ
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« Reply #1 on: September 06, 2012, 06:25:58 AM »

I use them in my AL-1500 all the time for years now. They work excatly alike to the 8877 in my amplifier.  Just as good if not better as I have experienced. Go for it.
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K6AER
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« Reply #2 on: September 06, 2012, 12:05:52 PM »

What is your source for 3CPX1500A7's at $250 each?
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K2FX
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« Reply #3 on: September 06, 2012, 12:42:16 PM »

Several are listed now and have been previously listed on Ebay for $250.00 or less.  As of this writing there are a few at less than $150.00.
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K2FX
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« Reply #4 on: September 06, 2012, 01:29:22 PM »

I've had a few emails relating to this post from individuals asking what companies produce them.  From what I've seen, Penta Labs, Richardson, and Eimac all manufacture them.
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W8JI
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« Reply #5 on: September 06, 2012, 02:17:47 PM »

I've had a few emails relating to this post from individuals asking what companies produce them.  From what I've seen, Penta Labs, Richardson, and Eimac all manufacture them.

Penta Labs used to be a specialty tube manufacturer in the 70's and earlier. They made tubes with the PL series, like PL-172's. They vanished. Many old timers here probably remember the PL172.

The name reappeared later. The Penta Labs that reappeared sold old scrap defective 8877 Eimac tubes as new. They would wash the tubes clean, re-plate them, and relabel them as Penta Labs. Ameritron bought some and they were 100% bad, and never got a refund. I think the owner of that time had criminal charges in California. They were the reason Eimac started embossing an Eimac logo into tube metal, to prevent counterfeiting.

Now I think someone else is using the name,  not connected to the mid-term owner. I think they are currently Chinese origin. I don't know any history of them currently, but I doubt it is the owner from the dark days.

AFAIK, Richardson's is only a distributor. They were, at one time, buying up every wholesaler and small manufacturer. They owned manufacturers. They bought Cetron and ran the price of 572B's so high no one could afford to use the tubes. They bought Amperex, and probably some I can't think of. Eimac entered into one of the dumbest agreements they ever entered into. They signed an exclusive distributorship with Richardson's. Richardson's sold competing tubes, some from their own plants. They were largely the reason tube prices skyrocketed in the 90's. Richard's was finally in an anti-trust action and forced to sell some companies, I know they sold Amperex to a former Richardson's manager. :-) You can probably find the terms of the settlement on the Internet, but as I recall they had to divest all the manufacturing.


Eimac and China are the only places I know of actually manufacturing 8877's. A 3CPX1500A7 at $250 must be a surplus pull. The 3CPX was a common old MRI tube. They were select-tested 3CX1500A7/8877 tubes. Anyone can get the Chinese to private label any tube. Chinese 8877's actually seem to be fairly good, but eveyone has had problems from time to time. Eimac had a long period and a few short periods years ago where they could not build a good 8877, so beware of certain batches of real old tubes.

73 Tom
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ZENKI
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Posts: 1648




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« Reply #6 on: September 07, 2012, 03:49:00 AM »

Tom

Do you know if the Chinese 8877's  has the same 2 tone 3rd order IMD performance as the genuine Eimac 8877?



I've had a few emails relating to this post from individuals asking what companies produce them.  From what I've seen, Penta Labs, Richardson, and Eimac all manufacture them.

Penta Labs used to be a specialty tube manufacturer in the 70's and earlier. They made tubes with the PL series, like PL-172's. They vanished. Many old timers here probably remember the PL172.

The name reappeared later. The Penta Labs that reappeared sold old scrap defective 8877 Eimac tubes as new. They would wash the tubes clean, re-plate them, and relabel them as Penta Labs. Ameritron bought some and they were 100% bad, and never got a refund. I think the owner of that time had criminal charges in California. They were the reason Eimac started embossing an Eimac logo into tube metal, to prevent counterfeiting.

Now I think someone else is using the name,  not connected to the mid-term owner. I think they are currently Chinese origin. I don't know any history of them currently, but I doubt it is the owner from the dark days.

AFAIK, Richardson's is only a distributor. They were, at one time, buying up every wholesaler and small manufacturer. They owned manufacturers. They bought Cetron and ran the price of 572B's so high no one could afford to use the tubes. They bought Amperex, and probably some I can't think of. Eimac entered into one of the dumbest agreements they ever entered into. They signed an exclusive distributorship with Richardson's. Richardson's sold competing tubes, some from their own plants. They were largely the reason tube prices skyrocketed in the 90's. Richard's was finally in an anti-trust action and forced to sell some companies, I know they sold Amperex to a former Richardson's manager. :-) You can probably find the terms of the settlement on the Internet, but as I recall they had to divest all the manufacturing.


Eimac and China are the only places I know of actually manufacturing 8877's. A 3CPX1500A7 at $250 must be a surplus pull. The 3CPX was a common old MRI tube. They were select-tested 3CX1500A7/8877 tubes. Anyone can get the Chinese to private label any tube. Chinese 8877's actually seem to be fairly good, but eveyone has had problems from time to time. Eimac had a long period and a few short periods years ago where they could not build a good 8877, so beware of certain batches of real old tubes.

73 Tom
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W8JI
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« Reply #7 on: September 07, 2012, 05:15:25 AM »

Tom

Do you know if the Chinese 8877's  has the same 2 tone 3rd order IMD performance as the genuine Eimac 8877?


I never have ran a two-tone test on a Chinese 8877, but there is nothing in the operating behavior that suggests a problem.
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W1QJ
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« Reply #8 on: September 07, 2012, 05:19:03 AM »

There's been some talk that Eimac 8877 tubes and maybe others are made in China using original Eimac tooling, sent here and branded Eimac.  Not sure how true this is but the rumor is out there.
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KG6YV
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« Reply #9 on: September 07, 2012, 08:05:22 AM »

I doubt that any rumor that Eimac tubes are outsourced to the Chinese has any merit.
I have a ham friend who has worked at Eimac for 30 years and he has indicated to me that Eimac still
manufacturers them. 

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W1QJ
Member

Posts: 2978




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« Reply #10 on: September 07, 2012, 09:28:57 AM »

I doubt that any rumor that Eimac tubes are outsourced to the Chinese has any merit.
I have a ham friend who has worked at Eimac for 30 years and he has indicated to me that Eimac still
manufacturers them. 


Naturally.
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N4TTS
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Posts: 253




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« Reply #11 on: September 07, 2012, 09:51:44 PM »

I haven't run any two-tone tests either but in my less than three month old AL-1500 I bought with an Eimac 8877, I am now running a Chinese manufactured tube I purchased from Greenstone.

The Chinese tube has more gain and the output doesn't appear to be any different on my HP spectrum analyzer than the Eimac.

Don N4TTS


I never have ran a two-tone test on a Chinese 8877, but there is nothing in the operating behavior that suggests a problem.
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KC4MOP
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Posts: 960




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« Reply #12 on: September 08, 2012, 03:34:35 AM »

This is nice to know that there is a way to work around replacement final tubes without breaking the bank.
But seriously, these tubes should last for years under typical Ham usage. Or am I not close to reality??
More Hams using high duty cycle modes and legal limit??

Fred
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W8JI
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« Reply #13 on: September 08, 2012, 02:23:27 PM »

This is nice to know that there is a way to work around replacement final tubes without breaking the bank.
But seriously, these tubes should last for years under typical Ham usage. Or am I not close to reality??
More Hams using high duty cycle modes and legal limit??

Fred

Fred,

Hams have the misplaced notion their use is easy on tubes.

While amateur filament hours or operating hours are very low, the poor tube is heated and cooled over-and-over in operation, generally (because people whine and moan endlessly about noise) has less airflow, is run harder, is subject to constant mistuning, and so on.

Don't think for a second amateur use is easier!

In commercial broadcast service, tubes loaf along steadily without cycling and just slowly wear down. In Ham use, grid get cooked, seals get weakened, metal is heated and cooled over and over and this might aggravate mechanical stability. Tubes also sit for long periods unused, where larger glass transmitting tubes might slowly leak around seals.

Then we have unpredictable manufacturing of tubes. Some tubes from China are more than 50% bad brand new.

http://www.w8ji.com/filament_voltage_life.htm

I'd expect many more hours in 24/7/365 broadcast than in amateur radio service. Broadcast is like running an engine at modest speed all year non-stop. Ham radio is like an engine in a drag car. Everyone wants maximum possible power while shutting the thing off and on all the time, sometimes for months or years.
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W1QJ
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Posts: 2978




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« Reply #14 on: September 09, 2012, 07:54:09 AM »

Considering what Tom had just said, this is why trying to adjust a filament voltage .2v would hardly make a difference in ham use.  Considering all the other damaging effects of ham use the filament voltage adjustment would only make sense if a ham was to keep his amp turned on 24/7 365.  Unless that is the case it is futil.  I'd say thermal cycling is the main culprit over time to the demise of tubes in ham use.  Yet, there are still older amps that have original tubes in them still going strong after many years. Still others fail because of operator error.  So many variables to consider.
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