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Author Topic: Collins 30L-1 tube flashover resulting in T-R relay inoperative?  (Read 17835 times)
VK6HP
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Posts: 525




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« Reply #30 on: September 23, 2017, 01:51:37 AM »

Jim,

After a bit of a search for a later edition manual, I downloaded a 9th edition from:

http://www.pestingers.net/pdfs/other-radios/collins/collins-30l-1-man.pdf

Rather interestingly, this is a 1 Feb 1968, 5th printing, and shows R28 as 39 ohm in the parts list but 47 ohm on the schematic!  By the time they got to my manual, which is 9th edition, 6th printing, Dec 1968, the manual was corrected to show R28 as 39 ohm in both places.

Thanks for the reference by Pappenfus et al. I've seen the title in passing and will take a closer look.  I've enjoyed reading "Fundamentals of SSB" which is also, of course, rich in Collins device referencing.  I've spent a good deal of my career working on the bleeding edge of radio but reading some of these earlier works convinces me that they should be better appreciated by contemporary hams and professionals.
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K9AXN
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Posts: 442


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« Reply #31 on: September 23, 2017, 09:48:28 AM »

Jim,

After a bit of a search for a later edition manual, I downloaded a 9th edition from:

http://www.pestingers.net/pdfs/other-radios/collins/collins-30l-1-man.pdf

Rather interestingly, this is a 1 Feb 1968, 5th printing, and shows R28 as 39 ohm in the parts list but 47 ohm on the schematic!  By the time they got to my manual, which is 9th edition, 6th printing, Dec 1968, the manual was corrected to show R28 as 39 ohm in both places.

Thanks for the reference by Pappenfus et al. I've seen the title in passing and will take a closer look.  I've enjoyed reading "Fundamentals of SSB" which is also, of course, rich in Collins device referencing.  I've spent a good deal of my career working on the bleeding edge of radio but reading some of these earlier works convinces me that they should be better appreciated by contemporary hams and professionals.

Pete,

Thanks for the URL.  I downloaded the manual and there's more surprises.  The input circuits for 10 and 15 apparently were changed a few more times and the bias circuit appears to have been goofed with several times. 

With that:  Any information that I have extracted from the archives, information letters, or any source from Collins is likely invalid and will be put aside.

That is not directed at their engineering staff i.e. Senti, the designer of the 30L1, Bruene a collaborator, or Pappenfus who reviewed it and brought it to market.  I believe the 30L1 to be the most forward thinking 811A amplifier design developed; most 811 amp developers mimicked the 30L1 design scheme.

Have a great day Pete and good luck Frank 

Regards Jim       
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N6QWP
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Posts: 735




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« Reply #32 on: September 29, 2017, 02:02:59 PM »

HAPPY UPDATE!!!

Turns out the VK6HP was correct in his surmising that the problem might only be that R28 blew.

It appears, thankfully, that nothing else was damaged in this event!

I appreciate all of the suggestions and inputs regarding what else might have been affected--and I have acquired most of those parts as spares, in case they are ever needed.  I (and I hope those that have followed this thread) have learned something from every contributed posting.

Going to install the MOV prophilactly, to protect as much of the associated circuitry that might be affected....to limit the damage from any further flashovers.

I will also replace those parts that have been updated in the "PRICELESS" CCA article of proven mods: "The Care and Feeding of Your 30L-1"

Many, many thanx, once again, to all that contributed their experiences, knowledge and time to help me sort out and get through my learning exercise--and get my 30L-1 back on the air.  73 all
« Last Edit: September 29, 2017, 02:21:19 PM by N6QWP » Logged
N6QWP
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Posts: 735




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« Reply #33 on: September 29, 2017, 08:22:07 PM »

Geez Jeeves, I feel almost as good as the day, waaay back when, that I finished my first kit....an Eico 720 cw transmitter, put it on the air and it worked!

After almost 60 years, with many of them away from the hobby, still love this ham radio stuff.  Love the idea that "Elmers" still exist....and that there is still a sense of accomplishment in solving new challenges that end up getting one "on the air".
« Last Edit: September 29, 2017, 08:40:25 PM by N6QWP » Logged
VK6HP
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Posts: 525




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« Reply #34 on: September 30, 2017, 03:14:18 AM »

Glad it worked out well, Frank, and congratulations on diving in and fixing it. Always good to see another operational 30L-1. I've only had mine a short time and I think it's truly a radio classic, with innovative (and pace-setting) thinking and robust construction.  At the same time, there are a few short-comings, not least of which are the instability modes which sometimes need taming and, in fairness, may be exacerbated by the motley tubes we're now having to use.   With a re-painted trim ring, a new HV power supply board and a general service which I completed a while ago, I think mine will look fine and work well for another 50 years.  It will be interesting to see if my new LDMOS amplifier makes the same milestone! (Mind you, I won't personally be around to judge the contest).
« Last Edit: September 30, 2017, 03:18:30 AM by VK6HP » Logged
N6QWP
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Posts: 735




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« Reply #35 on: September 30, 2017, 06:03:18 PM »

Not so worried about the instability issues on 15 and 10 meters.  I only use 40....could possibly expand to 20 and perhaps 75 some time in the future.

Worried about replacing the decades old, failing parts....and the real values and types of "modern parts" replacements that pertain to the 30L-1....and what other mods can help to keep the power transformer from being impacted from a flashover.  MOV's?  Electrolytics.  Modern resistors and capacitors? 
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K9RJ
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Posts: 76




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« Reply #36 on: October 05, 2017, 11:48:06 AM »

To VK6HP, could you direct me to Rev. 9 of the 30L-1 manual please? CCA only has 8th edition, 5 July 1966.
Thanks, Harris K9RJ
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K9RJ
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Posts: 76




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« Reply #37 on: October 05, 2017, 11:51:19 AM »

VK6HP, Please ignore previous message, found it at the link you sent.
73, Harris K9RJ ex VK6AV
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N8FVJ
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Posts: 888




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« Reply #38 on: October 06, 2017, 06:55:28 AM »

As mentioned use 572B tubes. With present line voltages, you may have 1800 volts DC on the tube plates whereas the stock 811A are rated at 1500 volts max.
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