Discussion in 'Amateur Radio Amplifiers' started by N8FVJ, May 4, 2019.
Find an old timer who is willing to downsize his collection at a fair price.
I have an al 811H with the 811a tubes for 5 years now and no problem so far....I do try to do the safe tuning procedure and also only use the amp on ssb
I have a few projects on the shelf but am not buying anything else that uses tubes. Price/performance does not justify. With DSP, solid state gear can be cleaner for less money. This goes for HiFi amps too where DSP can introduce tube like transfer function. Ten years ago, I felt differently. But tubes are too expensive now. 73, -Bob
Hello, and best greetings from Alaska.
I have a question in regard to domestic power tube availability:
Are the Eimac 3CX1500A7 and 4CX1500B power tubes still in production ?
Are either of these still made in USA ?
Here is reply from Tom Cox at Eimac , dated 18 February 2020:
Yes, we still manufacture the 3CX1500A7 and the 4CX1500B tubes as well as the complete line of Eimac brand tubes here in California.
$110.. in 1990 dollars is worth $203.89 in 2020 dollars. The inflation rate in the United States between 1990 and today has been 103.89%. That should be a consideration.
Some amplifiers and tubes are more reliable than others. Capacitors are not the only consideration when it comes to amplifiers.
Don't misunderstand. I tend to agree with you but for different reasons.
About 6 months ago I purchased a like-new Ameritron AL811H with four (16 extra, 20 tubes total) EXTRA sets of "new (never used) in the box" 811A tubes. The price I paid including shipping was LESS than the price of ten new 811A tubes at RF Parts.
I bought the amplifier, because, in my opinion, the price was a "steal."
When I got the amplifier home, I tested it into a dummy load to make sure it worked, unplugged it, and, have not turned it on since.
I have not transmitted at more than 10 watts in the last four years.
My Ameritron AL811H can gather dust just as good as an amplifier costing ten times the price I paid for the AL811H. Not a single one of the 20 tubes I got with the amplifier has failed. Granted, they may get gassy over time The tubes are all Chinese Taylor brand tubes.
"Tubes are not cost effective."
Surely you are not serious. Research the price of high power linear RF power transistors and compare it to tube prices. Tubes like transistors will last a very long time if they are not mistreated by trying to push an amplifier to higher than rated power.
Transistors, like tubes, can and will go bad if the amplifier is mistreated.
Another problem with transistors is that they become obsolete. I am afraid, that if in 20 years, you try to purchase high power linear RF power transistors for a solid-state amplifier gone bad, you will find them difficult if not impossible to obtain. Hopefully, there will be some sort of substitute available.
I feel certain that tubes will still be available for a 20-year-old tube type linear amplifier. Price/performance-wise, Dollar per watt, tube type amplifiers are much less expensive than solid-state amplifiers. Yes, you can buy a "solid gold Rolls Royce" amplifier. But comparing apples to apples. Tube type amps will win out every time.
Of course each to his own. I sincerely hope your experience with whatever you purchase is outstanding. Ham radio operators almost never think alike: and I am old and set in my ways.
Our sport just gets better every day. 73
I totally agree.
I have many amplifiers.
So I can add that for radio amateurs (i.e. amateur use, not commercial) there is no substitute for tube amps today.
Well, if your solid state amp dies and you are in warranty period, then your manufacturer may fix it (if they feel it's the amplifier's fault and not the operator's).
If it's out of warranty, then we are talking about hundreds of dollars for repair because changing transistors or MOSFETS or LDMOS is a lot harder and much different to changing a tube.
Almost all my amps are tube amps and they all work at spec levels(I own a solid state Tokyo HL-45B for the yaesu FT-817).
Regarding availability of tubes, I own many with the 3-500Z so such a tube is no issue. I found out that one can buy a complete amp with good tubes that cost less than if one were to buy tubes on their own. And you end up having a spare amp!
PS: One thing that should happen is that solid state amplifier manufacturers should offer much longer warranty periods, maybe 5 years or more. Then I may be tempted to buy a solid state amplifier.
OP: Thank you for this thread, it has inspired me to scour the market, and check my 'Spares".
4CX1000A, new Eimac available for immediate shipment from Nebraska at $795 ( Have one on the way )
Same from Israel, via Ebay $1450..... Did not accept my reasonable offer.
Went through and tested my ancient NOS spare Eimac 4CX1500B, pulled from the classifieds here on Da-Zed for $350, works great 45 watts in for 1500 out.
Tested an even older spare Eimac 4CX1000A, no visible date code, works great, 48 watts in, 1500 out.
After testing out the Eimac spares, I Stuck the ( new) FU728f chinese tetrode ( Array Solutions $400 ) in the EMTRON DX2sp Tetrode Tester/shack heater, reset the bias, filament voltage ( chinese tube requires 9 volts on the heater ) and cranked it up to 2100 watts into dummy load with 50 watts drive.
Turning the drive down to 35 watts makes 1500 to the antenna.
Removed the stock, OEM Eimac 3-500Z from my good old AL-80B, original date code from 1996, was making 800 watts out with 70 watts drive, and installed RF Parts chinese version, ($249 plus shipping) getting 750 watts output with 60 watts drive.
Plan to run the chinese tube until failure, keep the EIMAC for spare.
As far as old glass tubes, all new production is chinese, as far as I know.
Eimac claims to still have 3CX1500 and 4CX1500b in production, as of February, but it's a genuine puzzle how they'll continue to run a business in California with the current political/Economic conditions.
My advice : Stock up spare parts !
Thanks for the rundown with actual numbers.
It appears that your vintage of Eimac 3-500 has good seals. The Chinese replacement looks to be OK but time will tell about how it holds up. Very interesting!
I've been running my Taylor 3-500 for a few years and it's thankfully boring... which is good. Boring and high voltage go good together.