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Author Topic: "Burning in" tubes?  (Read 15806 times)
G3RZP
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Posts: 8123




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« Reply #30 on: September 14, 2017, 12:42:07 AM »


Quote
Seems like we're paying reasonable prices for HAM gear these days.

Especially if you look back to around 1948, when a surplus BC348 could set you back around $40 and a new HRO-7 with 4 coils, PSU and speaker was $311.36. An 813 was $14.50......

What was the average US worker's salary in 1948, and what is it today?




































































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KG4ABA
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« Reply #31 on: September 14, 2017, 10:54:56 AM »

Well...I can always count on my friends on eHam to provide me with advice...thanks, all!

Lynn-KG4ABA
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N3QE
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Posts: 4874




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« Reply #32 on: September 14, 2017, 11:28:42 AM »

Seems like we're paying reasonable prices for HAM gear these days.

I can buy a 3CX1500A7 for $800 that will last me a decade or maybe 20 years. Doesn't seem so bad when you divide it by hundreds of thousands of QSO's.

My back of the envelope calculation gives $0.002 per QSO.
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K6BRN
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« Reply #33 on: September 14, 2017, 11:18:17 PM »

Quote
The real issue here are hams are cheap. We want to buy tubes at 30 year old prices for our beloved 30 year old amplifier. I know of no other electronic hobby using equipment that dates back to when Nixon was president.

More likely hams that still use tube amps are cheap, because they provide the cheapest watt around, at the cost of a lot of TLC in operation and maintenance.  Because the people putting down $3K to $6K for newer solid-state amps in the 500W, 1KW and 1500W range certainly are not.  They just want to plug, play and cruise the bands and are willing to pay for the operating convenience.

Brian - K6BRN

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W8JX
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« Reply #34 on: September 16, 2017, 07:05:07 AM »

Quote
The real issue here are hams are cheap. We want to buy tubes at 30 year old prices for our beloved 30 year old amplifier. I know of no other electronic hobby using equipment that dates back to when Nixon was president.

More likely hams that still use tube amps are cheap, because they provide the cheapest watt around, at the cost of a lot of TLC in operation and maintenance.  Because the people putting down $3K to $6K for newer solid-state amps in the 500W, 1KW and 1500W range certainly are not.  They just want to plug, play and cruise the bands and are willing to pay for the operating convenience.

Brian - K6BRN


This sounds more about a brag factor that my amp is better than yours because it costs more and does not require tuning but it could also be viewed as these same hams are technically challenged and if it is not plug and play, they do not know how to use them or they are lazy. I think a tube amp is still better and not just because of cost and ruggedness. It does not need a perfect match with a tuner and can work with SWR of 2 to 1 or a bit more if need be. They could make a no tune tube amp but you would loose efficiency and the flexibility of a normal tube amp. 
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Ham since 1969....  Old School 20wpm REAL Extra Class..
K6AER
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« Reply #35 on: September 16, 2017, 08:50:25 AM »

Yes hams are basically cheap but new legal limit tube amps with good IMD specifications are still in the $4000 range. Serious contesting amplifiers are another $1500 above that.

Radio equipment ownership is not a right. If you can afford better equipment that is nice but hams haved always been welcomed with old basic starter rigs. The hobby is a gateway to knowledge. My first radio was a BC-348 and a ARC-5 on 40 meters. My grandfather, K6AER, helped set up the station with a dipole in the trees. He died soon after that, I was 10. This set me on a path to my BSEE many years later.
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N1CZ
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« Reply #36 on: September 16, 2017, 09:22:30 AM »

.
.
.
 It does not need a perfect match with a tuner and can work with SWR of 2 to 1 or a bit more if need be. They could make a no tune tube amp but you would loose efficiency and the flexibility of a normal tube amp. 
ding ding ding
Someone said something wrong on the internet.

Current LDMOS amps do not need a perfect match to the load. In fact there is at least one youtube genius that unplugs the output connection while the amp is at full output, 1kW to 2kW I don't remember ... perfectly terminated to an open. Reconnects the load and it still works. This is a feature of the LDMOS devices is that they are impervious to load variations. They are sensitive to input overload.
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W8JX
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« Reply #37 on: September 16, 2017, 09:59:48 AM »

Current LDMOS amps do not need a perfect match to the load. In fact there is at least one youtube genius that unplugs the output connection while the amp is at full output, 1kW to 2kW

ding ding ding

Sure they fold back but point is they do fold back on output a lot as SWR increases were a tube amp does not dah... 
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Ham since 1969....  Old School 20wpm REAL Extra Class..
N8CBX
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Posts: 478




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« Reply #38 on: September 16, 2017, 11:01:25 AM »

...they fold back but point is they do fold back on output a lot as SWR increases 
I think that's incorrect. I haven't built one using LDMOS yet, but I too have seen videos of the sparks & flame from a screwdriver short across a bare coax end.
Jan N8CBX
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Dayton Ohio - The Birthplace of Aviation
K5PHW
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« Reply #39 on: September 16, 2017, 11:36:18 AM »

 JX we know you don't like solid state amps. Don't you have an AL-811 tread to piss on?  Roll Eyes
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N1CZ
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Posts: 23




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« Reply #40 on: September 16, 2017, 12:48:57 PM »


Sure they fold back but point is they do fold back on output a lot as SWR increases were a tube amp does not dah... 
2:1 SWR is nothing.

In the 60s, my 1st linear was a homebrew 811A e/w roller inductor. I could tune that thing into random length antennas or a coat hanger ... eventually. Lots of fun if your fun is cranking knobs. Knobs were a wondrous thing. Now, I like to operate and quickly. I touch my touch screen computer display to jump to the freq, on whatever band, that I want plus a little tweak. Great fun is drilling into CW pileups in the same moment. Of course a couple of knobs come in quite handy for those final tweaks.

Don't get me wrong. I love tube amps. I dreamed about building 3-500Z amp for every band. Seriously. I loved my Hallicrafters, Drake 2B, & later R4C rcvrs. But, no more of those for me now either.

Slightly back on thread, if it was my tube and I read anything about burning it in, I probably would just to say that I did. IF I had a tube amp full power out and routinely ran RTTY or AM, I think it might be important. But, I don't do those anymore either, and not sure why. Those were the modes that warmed the room nicely in winter months. Nice long fillibuster like QSOs. When the room got warm enough, I ended transmitting. It just seems like tubes with those modes and that method of operation at full power out would benefit. Otherwise, meh.  Clearly just an opinion
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KM1H
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« Reply #41 on: September 16, 2017, 04:39:53 PM »

SS amps may be fine but the replacement parts may not be available in a few more years as they are discontinued for better parts. That has already happened with discrete transistors from HF to UHF.

Those with enough smarts to adapt other devices are probably OK but most of our current hamdom doesnt even know which end to hold a soldering iron.They deserve whatever it costs.

My commercial amps include 8122, 8873, 8874, 8875, 8877 along with 3-500Z but Ive purchased spares back when they were cheap and will outlast me.

Quote
They could make a no tune tube amp but you would loose efficiency and the flexibility of a normal tube amp.

Autotune tube amps have been around and in production since the 80's.

Carl

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W1NK
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WWW

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« Reply #42 on: September 16, 2017, 07:28:13 PM »


Quote
Seems like we're paying reasonable prices for HAM gear these days.

Especially if you look back to around 1948, when a surplus BC348 could set you back around $40 and a new HRO-7 with 4 coils, PSU and speaker was $311.36. An 813 was $14.50......

What was the average US worker's salary in 1948, and what is it today?

The median family income (before taxes) in 1948 was $3100 and $56,516 in 2015.

Frank, W1NK
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K6BRN
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Posts: 449




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« Reply #43 on: September 17, 2017, 01:22:17 AM »

John (W8JX):

Solid state amps are better than tube amps.   Much better, which is why almost every commercial application has switched to them.

Convenience  is not a "brag factor", its what all people gravitate to and why most cars in the USA have automatic transmissions.  Solid state amps are easier to use, go much longer without maintenence and for the most part, are much less prone to user destruction. (MFJ amps might be an exception)

Tube technology, now deep into its sunset years and with legendary parts shortages has the advantage of lower acquisition cost.  But much higher maintenence cost and operational complexity. 

Model T or Ford Explorer?  Easy choice if you have the means.  And good news if you dont because quality  used tube amps are getting cheaper every day, and there is a glut of them.  Windfall!
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G3RZP
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« Reply #44 on: September 17, 2017, 03:21:31 AM »


Quote
Autotune tube amps have been around and in production since the 80's.

Only for hams. Professional (kW and up) autotune transmitters have been around since the late 1950s

Quote
SS amps may be fine but the replacement parts may not be available in a few more years as they are discontinued for better parts. That has already happened with discrete transistors from HF to UHF.

You can include a lot of integrated circuits in that, too.

Some 15 years ago, they rationalised all military HF stations in the UK down to three sites out of which the three Services shared transmitters and antennas. The 5kW ones went to new SS tx's, but the 30kW ones were rebuilt Marconi auto tune transmitters dating from the 1980s as being the most cost effective approach....Despite government claims, there's even less real money available for them now...

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