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Author Topic: Problems with AL-572 and RF Parts "Taylor 572B Tubes"  (Read 17300 times)
W1QJ
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Posts: 2944




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« Reply #45 on: April 16, 2017, 08:36:15 AM »

First it was a debate over 1db being discernible and now 3db isn't a big deal?   What next?

Laughs,

W8JX is on a mission, what can I say.

For the record, .5dB SNR makes all the difference in the world to QAM16 x 512 carrier digital circuits (aka ADSL2+, baseband to 2MHz), so I'm in the 1dB makes a difference to experienced SSB / CW ops camp.  Every dB SNR counts in JT65.


For the record in a lab or on VHF/UHF where a rigs internal noise figure is the major limiting factor and with some modes (not SSB) 1db or so can make a difference but, some seem to try to equate this to HF SSB were QRN, QRM and QSB are major factors and with that 1db does nothing yet some want to believe otherwise and like comparing apples to oranges rather than apple to apples.

OK whatever.  Whoever does not want their extra db's I don't care how little I'll take them.  Thanks in advance.
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KM1H
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Posts: 5067




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« Reply #46 on: April 16, 2017, 08:46:45 AM »


I run the same 55 watts barefoot that I drive amp with....  3db is not a big deal plus when you use amp you seem more gain from 55 watts than 100

There is no change in power either way. At 55W the tubes are under driven and produce 1100W, at 100W 1200-1500W is the norm and surplus drive is passed thru to the antenna.



First it was a debate over 1db being discernible and now 3db isn't a big deal?   What next?


Laughs,

W8JX is on a mission, what can I say.

For the record, .5dB SNR makes all the difference in the world to QAM16 x 512 carrier digital circuits (aka ADSL2+, baseband to 2MHz), so I'm in the 1dB makes a difference to experienced SSB / CW ops camp.  Every dB SNR counts in JT65.
[/quote]

That mission was cancelled when he walked in the door. Shocked

As we all realize by now JX is one of those "casual" operators who has never moved beyond that entry level status and has never experienced what others enjoy where .5dB can be important even for CW on HF.
Everybody has there own interests, comfort, and operating ability levels but JX constantly wants to impose his own on everyone without realizing how undereducated he really is about this subject.

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W8JX
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Posts: 13268




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« Reply #47 on: April 16, 2017, 10:44:27 AM »

There is no change in power either way. At 55W the tubes are under driven and produce 1100W, at 100W 1200-1500W is the norm and surplus drive is passed thru to the antenna.

I like this under driven, what BS. If 55 watts was indeed under driven, increasing to 100 would go from 1100 watts out to 2100 watts if it was indeed under driven and it responded linearly to increase in drive power. But it does not because you are starting to over drive tubes and loosing linearity to gain a few hundred bragging watts. To some it ii just about the number/watts out and linearity be damned. When you cross the point were you no longer get a linear increase relative to power being applied you are in effect over driving tubes and getting less that optimum performance.

As we all realize by now JX is one of those "casual" operators who has never moved beyond that entry level status and has never experienced what others enjoy where .5dB can be important even for CW on HF.
Everybody has there own interests, comfort, and operating ability levels but JX constantly wants to impose his own on everyone without realizing how undereducated he really is about this subject.

It is more like how little you really understand db in real world application not theories. In HF work with QRN, QRM, and QSB 1 db IS NOT a deal breaker but some want you to really believe it is so they can tell you to push for that last possible watt at any cost and worry about a extra db of line loss too on HF because it will help a lot with QSO's when it is just BS. What works in a lab or VHF/UHF does not translate to HF. Once again no matter how much you want to you cannot compare apples to oranges to sell your spin.
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--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
KM1H
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Posts: 5067




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« Reply #48 on: April 16, 2017, 06:21:05 PM »

I give up, even CBers know more than this bozo
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KM4AH
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Posts: 945




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« Reply #49 on: April 16, 2017, 07:08:16 PM »

Quote
and it responded linearly to increase in drive power.

I have had a lot of amplifiers, but never one with a power supply capable of that.
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VK3BL
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« Reply #50 on: April 17, 2017, 12:25:50 AM »

On the subject of "blue in the tube"  if so many tubes can be bought that do not show any blue color in the tube, why should I or anyone else settle for a tube that does have blue color in it?  How would I know the difference if it is the "phenomenon" or really gas that someday might be an issue?

I'm not sure they can be; I'd bet the vast majority don't notice or don't care.

The blue tinge on the top of one of mine is so slight as to be easily missed if one does not look for it.

Either way, its a phenomenon acknowledged to not cause issues way before Shu Guang even began building tubes; its quite a common thing in the audiophool world... even to the point of being seen as a good sign, and hence the blue LEDs under the bottom of 12AX7s in a bunch of cheap 'studio' and home gear...

Its caused by stray electrons striking impurities in the glass; all tubes have stray electrons, and only audiophools believe that glass (other than that adequate for the proper operation of the tube) bestows magical or detrimental properties.

RF Parts likely restock said tubes and sell them to people like me who have read enough to know its a non issue.  After all, the warranty is more important with Chinese tubes than whatever predictions I can make by looking at one (in 99% of cases).
« Last Edit: April 17, 2017, 12:29:29 AM by VK3BL » Logged

J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
VK3BL
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« Reply #51 on: April 17, 2017, 12:39:11 AM »

I give up, even CBers know more than this bozo

Yeah well, well yeah.

To anyone reading this thread, linearity IS NOT measured by seeing how much power you can get out of an amplifier tuned for a given drive level, and then increasing drive and retuning.

Even drive power varied continuous single tone "linearity" cannot be measured accurately using Ham grade exciters and power meters. 

Achieving meaningful measurement of linearity (accurate to within a few dB) is not an easy task.  The cheapest (and most meaningful) way I can currently think of is to use a monitoring SDR Receiver such as an SDR Play RSP2 and enabling FFT averaging.  You then monitor your transmitted bandwidth whilst talking into the microphone.

One will then likely find the TX Bandwidth, Equaliser, Mike Gain & Compressor settings of their exciter play a much bigger role in determining final transmitted bandwidth and 'splatter' than exciter drive levels or the exact positioning of tune & load knobs. 

IMD and Linearity are nice things to hear Zenki wax lyrical about, but 'all knobs to the right and no station monitor' is a much bigger issue than whether your final has Triodes or Tetrodes.

« Last Edit: April 17, 2017, 12:46:40 AM by VK3BL » Logged

J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
PA1ZP
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Posts: 688




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« Reply #52 on: July 06, 2017, 11:34:36 AM »

Hi

I burned two sets of Chinese 572B's in my AL572B.
RF-parts say that all shuguan 572B'd will be rejects from them, that is why I still can buy 10000 of them in China if i want to for less then $10 a piece.

But yes good 572B tubes are very very hard to find, my friend has his AL572 as long as I do, he has Svetlana tubes in them still working like new after 10 yrs, i am looking for the third set of Chinese junk in 10yrs  and hope the AL572 will be up and running again soon.

my second set lasted for 7 yrs bought from High-Hope in China direct for $24 a piece 7yrs. ago .
Now I have to buy 500 tubes at least, no no way.

Should have bought the AL80B back then.
But hey 10 yrs of reasonably trouble free use (and i have used it a lot the first 5 yrs) I may not complain, as i now almost never use the amp.
Not a single hitch in the AL572B except for using 2 sets of tubes, the last set of 7 yrs old now start oscilating imideately after 5 seconds from start-up in stand-by mode, put in the 10 yr old warn tubes that were never even put in an amplifier for 7 yrs and the troubles of oscilating and drawing 150 mA anode current and heating up the tubes realy realy hot on top in 20 seconds are gone.
I was lucky that I always have my eyes glued to the amp meters when in use.

It only delivers 1 Kw PEP now and 800 key down, but hey i am only alowed 400 watts here so can still run these tubes for a while untill i find a replacement set of tubes or a replacement amplifier or without amp as i rarely use it now.

73 Jos
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KC4ZGP
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Posts: 1961




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« Reply #53 on: July 06, 2017, 01:14:26 PM »


Why the name calling?

On 20 meters phone at 2200UTC. Join me won't you?

Kraus
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