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What are some of the really good obsolete HF Amp Tubes

E

ElectronTubesRule

Active Member
Sep 6, 2011
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So we all know of the 100TH,150TH,250Th, 811,813,833,3-500Z, the 125,250,300,350,450 family and the 572B's.....What other killer glass envelope tubes from days long gone do you miss or they are pet tubes you really like a lot besides the ones above.

Out of the ones above which are your favorite and why? I am guessing it is going to be 3-500Z's and and 811's.

Any that I should keep an eye out for?????

It is hard to find good data on many tubes on power output in the real world. I have seen some number's that are two hard to believe but these are white paper and we all know how different lab conditions are then real world conditions. Any tubes that put out far less then you would expect and any that really are grossly under rated and consistently do better then their ratings? I know for HF most Russian tubes put out more power then they list. I think it is one of those conditions where you under promise so you know you can always over deliver!

Thanks guy's I love bouncing idea's off other people.
 

Since 811A's, 572B's,3-500Z's,813's, and 833's are still being made and for the most part still in common use in commercial amplifiers I would hesitate to call them obsolete, classic maybe, but not obsolete. One I would add is the venerable 4-400. There are/were thousands of 1 Kw class AM broadcast transmitters made that had either a pair of 833's in the finals or a pair of 4-400's. They provided lots of used pulls for the amateur community with the 4-400's being preferred as they had better high end performance, slightly better plate dissipation, and use the readily available 3-500 socket.For lower power the 6146 series is a good tube as is it's predecessor the 807.
 
Good correction on that definitely should be classic. I guess being 38 I consider most glass envelope tubes as yesterdays technology as in should have been ceramic by the time most of them came out. Imagine how much better most of those tubes would be with ceramic construction from a durability stand point. They would not be as pretty to look at though....

Also if you can not find American made versions of those tubes I consider them obsolete. From what I understand the 811,813,833, 3-500 and 572 Chineese made tubes are mostly junk and all the Russian stuff is NOS so again no current production. Unless I am mistaken their are no current production tubes made in America,UK,What was called Western Europe during the cold war that makes current production glass envelope tubes. Middle men in the USA want far too much for low quality Chi-Com made tubes and few come with any warranty I think RF Parts and MFJ are two of the few that ship their Chi-Com stuff with a Warranty of any kind unless things have changed.Nothing worse then getting a tube that should last 20 years and 3 months latter it arc's and is gone!!!

If I am wrong do correct me because I would love to get some new production American,German,British,Japanese made 833's,811,813's,3-500Z etc.......
 
China seems to be the only place still making glass envelope tubes AFAIK. When I was in broadcasting we used to purchase Amperex 833's and 807's for our 1 Kw class transmitters. When Amperex stopped making them we were forced to switch to National brand that was made in China. That was also about the time we switched from the 833A to the 833C with the graphite anode. Quality seemed to be pretty good but as time went on we found the Chinese National brand would not last as long in modulator service as the Amperex. With the Amperex we would install new tubes in the modulators and after six months move them to the RF final positiion and install new tubes in the modulator section.The tubes would see six months in heavy mod service and another six months in relatively light RF service and when retired after a year still had lots of useable life in them as emergency spares etc. The Chinese tubes would last six months in modulator service and by the time another six months of RF service was up they were pretty much used up.
 
811A is one of the greatest HF transmission tubes ever made, in my opinion.

It's inexpensive, rugged, has good heat dissipation, and most importantly, it's plentiful.
 
office888 said:
811A is one of the greatest HF transmission tubes ever made, in my opinion.

It's inexpensive, rugged, has good heat dissipation, and most importantly, it's plentiful.
Click to expand...


I concur,in fact I meant to mention that but forgot. While the 811A only has a plate dissipation of 65 watts they can withstand peak power dissipation of much more then that. The Ameritron AL-811 series of amps run them in excess of their power dissipation limits which is something rarely done in commercial amps. having bragged up the 811A's however I would NOT run them in AM service unless they were run well below their max values. Steady state carrier operation is really hard on the paper thin plates, so much so that blow outs are not uncommon in 811A plates.
 
I noticed a good deal of glass discoloration on both of those eBay tubes. This is usually caused by heavy electron bombardment on the inside of the glass. Very good indication the tubes have seen lots of use. One of them has the nerve to say it's NOS. If it were NOS the glass would be crystal clear with the exception of the getter flash marks.
 
Shockwave said:
I noticed a good deal of glass discoloration on both of those eBay tubes. This is usually caused by heavy electron bombardment on the inside of the glass. Very good indication the tubes have seen lots of use. One of them has the nerve to say it's NOS. If it were NOS the glass would be crystal clear with the exception of the getter flash marks.
Click to expand...

Obviously door stops but easy to find pictures.

The seller may be breathing NOx while typing NOS.
 
Yes a lot of seller list things as NOS based on Tube Testing not on it actually never having been used! LOL I have enough true NOS 6LQ6's and 6MJ6's to know that none of the OEM burned them in or tested them so no nice dark marks on the glass from NOS or NIB.....So if you see seep tubes with the dark burn marks on the glass rest assured they are not NOS or NIB even they do have tons of life left in them! No one was doing 48 hour burn in tests with TV Sweep Tubes! LOL As far as I know they never had a JAN ### for TV sweep tubes like the noval base cathode cap 6lq6's and that entire family of tubes! LOL

One guy has two Lindal 6LQ6 type tubes that are in the high 70% range and wants like $89 for the pair......I would rework an entire amp before I would pay that for sweep tubes!!!

Matching date codes passed off as "Matched Pair" no emission testing done.....All sales final as-is for a $79 tube I do not think so! LOL Paypal always takes the side of the buyer or almost so!! So do not let their declarations of As-Is all Sales Final fool you!!!

If the price is right I would buy used tubes if they tested out very well.


Oh and no OEM was useing matched tubes! Would have been nice to have tubes matched by emission to 7% of each other sure it would. As soon as those tubes have a few months of wear and tear they will all test differently. Can you imagine how labor intensive it would have been for D&A to match 12 sweep tubes to with in 7% of each other for their triple stage Phantom model????LOL

We also know that none sweep tube Amps built by OEM's like Ameritron did not bother to match their tubes during production either. Matching of tubes is a money maker for the people selling the tubes. I have seen too many amps get retubed with any brand or mix of brands they could find as sweep tubes started to get scarce work just find and live long healthy lives with mis-matched tubes by mismatched I mean different brands and different levels of emissions on tester but all where new tubes and all where the right tube.

In fact I think it is much like " Like components in series will share the load" so if they are similar enough they will share the load for the most part. Even with matching you will never get 100% equal load sharing or emissions and that is due to what happens at the quantum level always some randomness in the universe to account for!
 
Today the EL-509 is the king of the sweep tubes. If they physically fit inside your equipment, the modification is well worth it. I've even modified some Yeasu FT-101's to take these tubes when the originals hit almost $200 a set. Not an easy job since the RF compartment needs some modifying to accommodate the larger tube. One should be aware of a flaw I've noticed on some EL-509 tubes. The large pins on the base of the tube have heat issues. The two that connect to the filament tend to conduct large amounts of heat through those pins.

I've seen at least 6 cases where this pin will crack the glass envelope around the pin and fracture the tube seal. At the time RF parts claimed the failure was due to the tube sockets being used. Being that I purchased the recommended porcelain sockets, their excuse was ridiculous. Especially since the problem always occurs at one of two filament pins with nothing more then filament voltage applied. If this production error has been fixed, I vote for the EL-509 as a replacement for all sweep tubes where the space is available.
 

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