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Author Topic: 811A TUBES GLOWING BRIGHT ORANGE DURING SLOW CW-TOO MUCH OR OK?  (Read 4679 times)
N6QWP
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« on: March 12, 2017, 07:43:16 AM »

Just noticed that during CW transmissions, the anodes on my 4 811A tubes in my 30L-1 glow bright orange.  Operating at about 8-10 wpm, so not much time for them to cool down between keying.  Power out is about 475-500 watts.

Never noticed this on SSB.  Wondering if I should reduce power on CW?  I have read that glowing plates of different shades of orange or red is normal-but, depending on which color, might also be damaging???

Anyone have this experience and what was the outcome?  What color and shade is OK-if any?  I am enjoying getting back on CW, but don't want to ruin the tubes prematurely.  My inclination is to drop power until there is no glowing....but if not necessary, would like the additional power.  Thanx for your input.
« Last Edit: March 12, 2017, 08:03:14 AM by N6QWP » Logged
WB2WIK
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« Reply #1 on: March 12, 2017, 08:13:34 AM »

I'd say that's not normal.    Sounds like too much plate current.   Possibly the Ip isn't dipped?
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N6QWP
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« Reply #2 on: March 12, 2017, 08:20:46 AM »

Amp is tuned to normal settings (max power= dip) for SSB.  Only using 40 meters, so not changing bands.  I am moving down to the lower end of the band, though.  I will double check.....it is possible, that by QSYing, I do need to re-tune.  Thanx....I'll check that out.

Still wondering if any color is OK when using CW?  If I reduce power by about half (200-250) I can pound for a good while without worry--but that is not a noticeable increase from 50-100 watts.
« Last Edit: March 12, 2017, 08:33:14 AM by N6QWP » Logged
WB2WIK
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« Reply #3 on: March 12, 2017, 08:50:35 AM »

You do need to re-tune when you change frequencies on 40m by more than about 100 kHz.   If you're "tuned up" at, say 7200 kHz and then QSY down to 7100 or lower, you do need to re-dip the amp.   How far you can change frequency without retuning varies by band and also by your antenna characteristics, but 100 kHz change or more on 40m does require re-tuning.

I've owned 30L-1s and never saw any anode color with them in normal operation on SSB or CW.  It's not a good choice for AM operation.
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N6QWP
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« Reply #4 on: March 12, 2017, 08:58:47 AM »

I agree.  Just tried using it on CW last night, and didn't think to re-tune (just switched from VFO 1 to VFO 2 on rig to QSY).  Makes sense.

Haven't used tube finals for decades, so it slipped my mind.....so used to working with solid state finals and staying within the phone portion of the band.  Appreciate the fact that you also had a 30L-1 and never had the tubes glow.  Will try retuning this evening-when I can see the tubes in the dark.

I probably ruined the 811A tubes, but they have "newbie practice time" on them and am glad to be getting past the learning curve before putting in the new ones.

Still wondering if I should operate CW at reduced power though, since at slow speeds, it's almost like tuning too long without enough time for the anodes to cool properly?
« Last Edit: March 12, 2017, 09:18:17 AM by N6QWP » Logged
N6QWP
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« Reply #5 on: March 12, 2017, 03:21:51 PM »

You called it correctly!  Just retuned down on the low end of 40 CW and the dip was waaay off.  Thanx for noticing that.  There is a big difference in where the tuning cap is between the two ends of the band.  So obvious that I forgot it.  Always glad to learn something old....again. Grin  

I'll do CW this evening and see if I can run full power without the anodes turning colors.....or not?  73
« Last Edit: March 12, 2017, 03:32:53 PM by N6QWP » Logged
K0ZN
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« Reply #6 on: March 12, 2017, 06:42:22 PM »

Those 811A anodes should NOT be glowing brightly. A slight very DULL redness to appear on the center of the plates is OK. If you have not run them that hot too much,
 they may be OK.....only time will tell. Despite what the Ameritron ads say, the 811A is not a "tough" tube. To the contrary, it is a fairly fragile tube with tiny grid wires and thin plates that heat quickly. The grids in particular are a weak point from the stand point of over drive. Heed the warnings in the Owner's Manual about maximum allowable grid current; the warning is real. The time vs. temp curve on the plates allows for a little more error, but abuse will kill the tubes....and in the worst case cause an internal short and take out the meter diode and possibly other things. The original 811A ("back in the day") had an ICAS plate dissipation rating of 65 watts. The current Chinese tubes don't seem to be quite that high. Such being the case, with 4 tubes, you have a total plate dissipation of around 260 watts. Assuming, some what optimistically, that you have a 70% efficiency....which is stretching it.....that would mean *theoretically* you could drive the amp to about 370 watts output on slow CW (SSB is a much lower duty cycle, therefore the high PEP rating). In the real world (due to circuit design, tank circuit parameters and the load & SWR presented to the amp, etc.), the color of the plates will tell you more than the actual output reading on the meter. Assuming the amp is correctly tuned up on a specific frequency, raise the drive in increments until you see a little color, then back off a little. WB2WIK is, as you found, spot on about retuning as you QSY. My experience has been that 50 Khz QSY merits a re-tune, but maybe I am too conservative. For full disclosure:  I have an AL-811 (3 tube) as a back up amp. I have noted that on 80 and 160 there is not enough capacitance in the loading capacitor for the very low ends of those bands. (Apparently Ameritron pretty much designed it assuming most operation would be in the SSB portion of those bands.)  I operate almost exclusively CW, so I had to add some C and move the 80 M tank coil tap one turn to allow the circuit to become efficient enough to keep the tubes from over heating on the low end of 80 CW. That problem does not occur on the higher bands. If you find the loading cap turned fully CCW that is not good and the tubes will likely get hot quickly. I found on my AL-811 that I typically can drive it on CW to about ~300 W output with the tubes showing only the slightest dull RED glow in the center of the plates during a long CW transmission....and that tiny color is OK on an 811A. As a guess, I would say you probably safely can drive your 4 tube amp to about 360 watts out for slow speed CW. If you use that amp on data or RTTY for long transmissions, you really should use the CCS ratings.  You will have to play with it to find out where it is "happy". Properly used, those 811A's can last quite a while. Pushed hard and over their thermal ratings, their life will likely be pretty short. My experience has been that the amp and the 811A's are quite reliable IF they are operated with in their design parameters. Frankly, I suspect one of the reasons we see a lot of 811A amps for sale used is because many hams don't understand the care and feeding of tube type amplifiers and ruin a lot of tubes and then decide the Amp is the problem.....when in reality, it is an operator problem.

  "Your results may vary....."

        73,  K0ZN
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N6QWP
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« Reply #7 on: March 12, 2017, 07:34:41 PM »

Thank you both for your insightful comments.  I have just been on CW and the room is now dark enough to verify that when properly tuned for maximum output for the frequency that I am operating on, the amp can run full power and no discernable glowing on the anodes.

Probably a couple of lessons learned here......and I am beholding to those gents who informed me of what I had either forgotten or overlooked.  Sometimes, the most obvious and simple things can be the easiest to skip over.  

I hope this thread is helpful to others who, in their haste to try out a "new toy", can get into trouble by not following the instructions.
K.I.S.S.!
« Last Edit: March 12, 2017, 07:36:57 PM by N6QWP » Logged
VK3BL
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« Reply #8 on: March 12, 2017, 07:53:59 PM »

The grids are nearly indestructable.  You will NEVER damage a grid before a plate.  Anything other than dull red is a tuning error.

Please use the search function, read W8JI's website, read the RCA Datasheets and/or the RCA Ham tips pamplet covering the 811A, or even read previous replies to your many other threads.

Capitals are NOT needed in thread titles.

God helps those who help themselves.
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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
N6QWP
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« Reply #9 on: March 12, 2017, 08:55:07 PM »

While "god" may help some, this forum has proved to be an invaluable source of information for hams helping hams with everyday issues and does not necessitate divine intervention.  Having read all of the above suggested information, questions still arise.

While simplistic and mundane (even repetitive) questions might tend to irk some people, in the interest of gaining and sharing knowledge, many issues which appear here, do pass along help to new and some not so new folks to the hobby.

To those who share their knowledge and expertise with those of us still learning by doing (and in some instances by not paying attention to all the details involved), I would like to say thanx.  It's always nice and reassuring to have someone answer a question that comes up directly-not needing to interpolate information that is relative to a problem but not exactly on point.
« Last Edit: March 12, 2017, 09:17:15 PM by N6QWP » Logged
VK3BL
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« Reply #10 on: March 12, 2017, 09:50:49 PM »

While "god" may help some, this forum has proved to be an invaluable source of information for hams helping hams with everyday issues and does not necessitate divine intervention.  Having read all of the above suggested information, questions still arise.

While simplistic and mundane (even repetitive) questions might tend to irk some people, in the interest of gaining and sharing knowledge, many issues which appear here, do pass along help to new and some not so new folks to the hobby.

To those who share their knowledge and expertise with those of us still learning by doing (and in some instances by not paying attention to all the details involved), I would like to say thanx.  It's always nice and reassuring to have someone answer a question that comes up directly-not needing to interpolate information that is relative to a problem but not exactly on point.

Appreciated, and my reply was indeed curt, but rightly so, and I will give you the courtesy of an explanation.

The thing is, you may find out that if you don't do at least a modicum of your own reading etc, that in future you will miss out on replies from some of the more experienced members of these forums.  They will just stop replying every time they see an ALL CAPS THREAD, or your call sign.

For example: Carl KM1H, Glenn W9IQ, John W8JX, Lou W1QJ, Steven WB2WIK & myself have all answered the questions you're asking well over 50+ times on these forums.  In the case of Carl, probably more like 1000 times to the point he gets well grumpier than I may seem now on occasion.  Trust me, you don't want to get on Carl's bad side! Smiley Whilst most of us are happy to assist a newcomer, the facts are as follows:

The answers to the questions posed in THIS VERY THREAD have been covered IN DETAIL in two of your previous threads by myself and others, please consult them, as below:

http://www.eham.net/ehamforum/smf/index.php/topic,113760.0.html
http://www.eham.net/ehamforum/smf/index.php/topic,113809.0.html

If you have further questions, you should re-post in your previous threads.  Continually opening ALL CAPS threads is annoying, and I do not believe I am alone in this belief.  If others believe I am out of line, please email me via my QRZ.com email address.

The hobby of Amateur radio is based on self-education in radio communications, not being spoon feed answers to questions time and time again that you have already asked.

If you consider my reply rude, consider this:

This is the first time I have ever had to point out to ANYONE on these forums that they are posting duplicate thread topics mere days apart.  Myself and others have spent considerable effort assisting you in your learning, and quite frankly, I find it rude that our replies are seemingly ignored and the same questions keep coming up from the same person in new threads time and time again.  If you have found any of our previous replies inadequate, pay us the respect of telling us why in the appropriate thread.

To be clear, I am happy to help ANYONE on ANY TOPIC, but only if they pay me the respect of listening.  You seem to have a grasp of written language, so I can only assume you are equally good at reading.  If you have memory problems or some other form of learning disability, please do let me know (publicly or privately via my QRZ.com email), and I will issue you an immediate apology. 

If not, please endeavour to consult your previous threads in depth before deciding to start yet another.  Please consider this reply to be helpful advice regarding eham forum etiquette, rather than a personal attack.  The whole community would rather that when the time comes (e.g. you have a unique and interesting problem), everyone with experience is willing to help.

You will not be 'punished' or seen as a pariah by reviving any of your previous threads when new questions arise - that is the proper etiquette in the eham amplifiers section.
« Last Edit: March 12, 2017, 10:06:39 PM by VK3BL » Logged

J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio - Honesty & Integrity
N6QWP
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« Reply #11 on: March 13, 2017, 10:04:27 AM »

I guess that I am slow to comprehend the references you make to my previous listings and how the question raised here (about CW operation-and my observations-and concerns thereof) were answered by anyone in previous posts.

I may have incorrectly assumed, that if one had a "new issue", then it deserved a new thread.  I will try to refrain from asking any more questions about the proper use of the 30L-1.  I will note, however, that being specific.....and asking for insights or advice and not lumping it at the tail end of threads that have gone through the convoluted process of change and often getting way off subject, did work for me in this instance and in several others.

Thanx to N0ZN, I was able to find out what had eluded me....and yes it was due to my failure to pay closer attention to detail.  Sometimes it takes the observations of others to "point our the individual trees in the forest".

Since this 30L-1 811A amp is my first and "after reading the many posts and articles you referenced", I was very apprehensive of destroying either the tubes or expensive and hard to locate parts.  The questions I asked in various threads might, I thought, be ones that other newbies might also have and could elicit answers that we could learn from.

PS-I will accept your admonishment and not use all capitals should I start another thread.

To the numerous other hams who put up with my inane and repetitive questions and offered advice, I wish to pass along my heartfelt thanx.  I have "weathered the storm" and now feel comfortable and able to operated this old classic amp without causing any further damage.  It took the aid of Elmers to drag me through the darkness.....and perhaps some higher help too.  73 all
« Last Edit: March 13, 2017, 10:17:08 AM by N6QWP » Logged
N6QWP
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« Reply #12 on: March 13, 2017, 10:40:52 AM »

I forgot to personally thank WB2IK for his help in isolating my error here.  While "God helps those who help themselves", sometimes other mortals come to the aid of those in need.  But, I guess "God would be more forgiving of our trespasses".
« Last Edit: March 13, 2017, 11:04:14 AM by N6QWP » Logged
N6QWP
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« Reply #13 on: March 13, 2017, 11:26:05 AM »

My apologies.....that should have read: additional thanks to WB2WIK.....and VK3BL.....and to all of the others that have inputted in my quest for knowledge here on eHam.net Forums.
« Last Edit: March 13, 2017, 11:37:37 AM by N6QWP » Logged
W8JX
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« Reply #14 on: March 13, 2017, 11:51:42 AM »

I think there is some misconceptions about safe operation of a 811 tube which is a light duty amp tube at best rated at olny  . One must remember that it has a thin metal plate and it is not designed to be operated in a "glowing" state. You should never see more than a very dull red in center of plate when operated in a safe manor. Tubes like 572's have a thick graphic anode/plate that can handle heat without wrapping or melting and can be safely operated in a glowing state, a 811 cannot though without shortening its lifespan and risking sudden failure yet many seem to think so and push envelope.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
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