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Author Topic: SEEKING INFO ON EARLY NCX-3 POWER SUPPLY? NOT REALLY BOAT ANCHOR BUT OLD  (Read 2133 times)
N6QWP
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« on: September 18, 2018, 07:40:11 PM »

I acknowledge that the NCX-3 doesn't really qualify as a traditional "Boat Anchor", but it is old enough to make it difficult to look up the answer to the question that I have....and I didn't know where else to ask.

Searching online, the pics of the AC power supply all have a speaker with it in a speaker cabinet.  I found one without the speaker...but it is eerily close in voltages, parts, layout and circuitry, that I am wondering if the earliest one(s) might have come without the speaker?

It is possible that this one might have been a prototype....or even a VERY CLOSE CLONE, but many things are soooo close (and many parts are identical) that it makes me wonder.  The one that I found does have a toggle switch on the top of the chassis with decals that read 115 and 230 (volts?).

Any old timer users of this rig, or "manual collectors" know if this might have been an early original model? Unfortunately time and exposure has caused enough surface rust on the chassis that any other decals have been obliterated.
« Last Edit: September 18, 2018, 08:03:16 PM by N6QWP » Logged
KE0ZU
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« Reply #1 on: September 18, 2018, 09:15:58 PM »

I think what you have is either an AC-200 or AC-500 power supply.   These supplies had no internal speaker and were used with the NCX-200 and NCX-500 transceivers, and had a switched dual primary winding.   I believe neither were a big production quantity radio so the associated supplies would be somewhat uncommon as well.   The 110/220 switch was accessible a hole in the rear of the cabinet. 

Click on the picture, it's a link to more pics/infofmation.



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Regards, Mike
https://mikeharrison.smugmug.com/
Pics and bold print are usually links.
N6QWP
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« Reply #2 on: September 18, 2018, 09:28:39 PM »

Did find a few youtube videos on the NCX power supplies (several different editions) and did find one that was even closer to what I have.  It had the same toggle switch and power transformer.  Similar chokes and most all parts were either identical or very close.

After further exploration, I guess that these rigs do qualify as Boat Anchors....so the power supply question should be in the right arena.

The one big difference is that the ones that I can find online all seem to have several horizontal ventilation openings in the chassis.....whereas, the one that I have does not.  That and the lack of a speaker seem to be the two major changes from mine.

Wondering if National might have had an earlier transceiver than the NCX-3 and NCX-5 that would have used the same type of external power supply?

I am more convinced now, than ever that this is an earlier model....but still made by National.....OR, indeed a prototype for the NCX rigs' supplies that I see online.  I already found that the earlier supplies worked on 115 and, or 230 (as does mine).  Later ones seem to only have 115 windings (on the later schematics at least) and no toggle switch on the chassis.

Would still appreciate any comments from any old users who might be able to shed some light on this issue.

-----------------------------------------------------------------------------------------------------------

KE0ZU-Thanx Mike, you posted while I was writing this entry.  I will try to find pics of those and see how they compare....BUT, the voltage requirements do seem to be the same in the NCX-200.  I couldn't find any pics yet, on what the AC-200 looks like.  You don't happen to have access to some pics, do you?  I love to see some chassis views.

You may very well be correct....I will try to find something on youtube.  I'll get back after I can look into it further.  Tnx es 73
« Last Edit: September 18, 2018, 09:47:11 PM by N6QWP » Logged
KE0ZU
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« Reply #3 on: September 19, 2018, 03:30:36 AM »

The only pics I have are those at my linked pic post site.   I also have a schematic for the AC-500,



It is my understanding the single input power supplies for the NCX-5 and NCX-500 used the same power transformer, they simply left out the HV choke, resulting in +1100 Volt B+ for the NCX-500. Compare with NCX-A schematic below.



I also happened to find this pic from my original NCX-5 station, of  the power supply and the 110/220 switch.



« Last Edit: September 19, 2018, 03:51:36 AM by KE0ZU » Logged

Regards, Mike
https://mikeharrison.smugmug.com/
Pics and bold print are usually links.
N4MQ
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« Reply #4 on: September 19, 2018, 04:14:23 AM »

A power supply with 700 - 1100 volts AND speaker connections on the SAME connector, that is NUTZ.  There must be no safety considerations in the design, UL or ETL or even RU HuhHuhHuhHuh? Woody  OBTW the switch for power selection is not referenced = labeled ??
« Last Edit: September 19, 2018, 04:17:31 AM by N4MQ » Logged
G3RZP
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« Reply #5 on: September 19, 2018, 04:25:56 AM »

Exceeding voltage ratings on connectors was not uncommon in  manufactured amateur and commercial radio - and even in some UK military stuff.
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N6QWP
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« Reply #6 on: September 19, 2018, 06:49:47 AM »

I've searched the internet exhaustively, but was not able to find any pics of the NCX-200 power supply chassis...…(NCX AC-200)

It certainly seems plausible that what I have might be exactly one of those.  The lack of elongated vent holes in the chassis would confirm that....as all other indications point in that direction.


******SEEKING CHASSIS PICS OF THE ORIGINAL POWER SUPPLY FOR THE NCX-200*******
                       (OR EVEN OF THE CHASSIS PICS OF THE NCX AC-500)


Hopefully, someone out there has one of these seemingly rare supplies (OR CAN SUPPLY A FEW PICS OF IT)Huh??


 
« Last Edit: September 19, 2018, 06:59:39 AM by N6QWP » Logged
AB1MN
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« Reply #7 on: September 19, 2018, 09:44:00 AM »

Hi,

Here is a photo of the top and bottom on my AC-500 supply. This was not intended to mount in an enclosure as there is no provision for mounting a speaker. The NCX-A supply for the NCX-3 and NCX-5 transceivers has a cutout at the front to clear the speaker frame.

Also, note there are no ventilation slots above the bleeder resistors. This power supply has been re-capped so these are not the original caps. The AC-500 has three caps in series for the high voltage and the AC-200 has only two caps in series. That is probably the easiest way to visually distinguish between the two.

And yes, the power connector is the same for all of the power supplies.

Here is a link to the photos of my AC-500 (copy and paste in your browser):

https://www.dropbox.com/sh/10yzyhg9t0xqru2/AAC0dUQkULRBJ9YCSl0jAmyna?dl=0

Bob, AB1MN


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KM1H
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« Reply #8 on: September 19, 2018, 09:49:28 AM »

There were two versions of the NCXA PS, the original for the 6GJ5A finals and the other for the later 6JB6A finals which were in the later production NCX-5 and retrofitted into the NCX-3. Just a minor change to the LV.
The original is at the end of this
http://bama.edebris.com/manuals/national/ncx3/

The NATIONAL 200 used the reduced cost AC-200 or the later NCX-A; same supply minus fancy case and speaker. The manual says NCX-200 but was dropped for copyright reasons when the National name was sold to Panasonic in a desperate attempt to raise money. A new label was used on the rigs.

Those were rather hectic and confusing years that I lived thru as Service Manager and Sr Engineering Aide and changing hats between the 2nd and 3rd floors Roll Eyes

The NCX-500 used a modified AC-200, same transformer and most other parts which would make it good for 811A's

Carl

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N6QWP
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« Reply #9 on: September 19, 2018, 10:43:59 AM »

THAT'S IT!  THANX MIKE AND BOB AND CARL!  

I knew that it had to be something like that.....just needed confirmation.    

It's so great to be able to search and FIND the answers to all of these questions here on the Forums.

Yes Carl, this supply, with new caps and diodes….and perhaps even using a HV switch to alternate between this choke 700 vdc supply output and using the old 30L-1 supply boards (for doubling that?), appears might work just fine to do the original testing of those old 811's and 811A's (even 572B's) for gas?

Still wondering whether to use a HV wire wound pot to vary the bias voltage....or if I could just use a common volume control???

Turned out to be a fortunate "$10 score" at the ham swap meet that I went to in search of just such a supply or transformer.

Thanx again to everyone for all the great info and help with this project.  73

« Last Edit: September 19, 2018, 11:04:02 AM by N6QWP » Logged
KM1H
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« Reply #10 on: September 19, 2018, 04:00:46 PM »

Yep, it can be used with 572B's and with enough bias they can even show good color for regettering.

The bias supply needs draws very little current so any decent 1/2 to 1W pot will do.

Carl
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N6QWP
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« Reply #11 on: September 19, 2018, 04:39:14 PM »

Thanx Carl--I notice if I remove a resistor I can increase the bias voltage.  Would I want MORE BIAS VOLTAGE to get the current draw on the tube up....OR LESS?  That simple change seems to increase the available bias from 80 to over a 100.

After re-reading the threads, I realize that you seemed to recommend doing the "500 mod" to increase the available HV voltage from 700 to 1100 (still under the 1200 volt "threshold" for flashovers....if I understood your earlier responses)?

Would you still consider using the original 30L-1 power supply boards (caps and diodes) as an switched "extra" available higher voltage (to 1800 or more?).....OR, if the 811's and 811A's passed the "gas test" at 1100 vdc, would you pass and save the final test using the 30L-1 and "loading them up with RF"Huh

I realize that you used the increased voltage option in your "test platform" to test the 572B's.  I do have a number of them that need testing, so adding the original 30L-1 boards...."WITH a HV switch" to change output rectification....and thus the available HV,  would still make sense?  

Please excuse....and hopefully put up with all of these questions, but I am still learning (or re-learning) and hopefully, the questions that I raise will have some benefit to some of the other readers of this thread.

« Last Edit: September 19, 2018, 05:01:13 PM by N6QWP » Logged
KM1H
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« Reply #12 on: September 20, 2018, 07:45:33 AM »

Quote
Thanx Carl--I notice if I remove a resistor I can increase the bias voltage.  Would I want MORE BIAS VOLTAGE to get the current draw on the tube up....OR LESS?  That simple change seems to increase the available bias from 80 to over a 100.

You need a positive bias voltage to obtain sufficient current which was why I suggested a separate PS for that.

Just get that AC-200 functioning so that it can test 811A's and forget about using the 30L1 for anything more than tube sockets.
No more questions for now about future use.....stick to one thing!
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KE4OH
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« Reply #13 on: September 20, 2018, 10:00:52 AM »

I acknowledge that the NCX-3 doesn't really qualify as a traditional "Boat Anchor",

I can't help with this particular power supply, but NCX-3 and accessories most definitely qualify as genuine boatanchors! Anything from the all/mostly tube era qualifies. As do the hybrid rigs.
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73 de Steve KE4OH
N6QWP
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« Reply #14 on: September 20, 2018, 01:12:12 PM »

Thanx Steve--I already acknowledged that I later did consider it a Boat Anchor.  I didn't have the rig that it went with, so I wasn't sure upon first post.

       xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx


Carl--Got it.  Didn't realize that the bias had to be positive!  I will look for a variable power supply to provide that......wonder what is the "HIGHEST POSITIVE BIAS VOLTAGE" that will be required to get those plates glowing?Huh  When I get that info, I will be off in a search for the correct external supply.

I will be making the changes in the AC-200 to increase the HV to the 1100 vdc.....while I replace the caps and diodes.....and worry about getting the 30L-1 going later.  I found a couple of sockets for the 811A's....now, will just need to build up a chassis that will safely allow me to test the tubes without getting ZAPPED!  

As always, many thanx for your Elmering help.
« Last Edit: September 20, 2018, 01:24:46 PM by N6QWP » Logged
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