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Author Topic: Plate Current Meter for Drake L-/L-4B  (Read 726 times)
VR2AX
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Posts: 589




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« on: May 31, 2008, 04:19:38 AM »

Does anyone know of a source for replacement plate current meters for a Drake L-4 or L-4B?

I put my L-4 back on line today after a couple of months layoff due to rewinding the plate choke. The plate current meter decided to say goodbye at this time.

The amp works but the meter is not working so I have pulled it. It is presently connected up to my Fluke 189 for the purpose of getting a Ip reading.

The meter is a Honeywell Model MS2T 1A DC meter, the number on the face is 823354-0084.

Any help or suggestions gtarefully received.

73, VR2AX

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K7KBN
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Posts: 2802




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« Reply #1 on: May 31, 2008, 08:08:05 AM »

Lots of possibilities; this is only one of them:

http://www.mail-archive.com/drakelist@www.zerobeat.net/msg08711.html

Google on ms2t honeywell meter and see what comes up.  There may be something local to you there in Hong Kong.

73
Pat K7KBN
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73
Pat K7KBN
CWO4 USNR Ret.
VR2AX
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Posts: 589




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« Reply #2 on: May 31, 2008, 08:21:27 AM »

Pat,

Thanks for your reply. I have tried the local shops today. I have two nice Japanese meters unfortunately none look like the original. The old girl wishes to reclaim her citizenship.

The ebay link is useful I will follow it up.

Cheers,
Wyn VR2AX/Gw3ygh
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AE5I
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Posts: 124




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« Reply #3 on: May 31, 2008, 09:11:11 AM »

Hi Wyn-

I definitely remember seeing L-4B plate ammeters on ebay in the past.  Seems like I remember seeing a new one and then a used one when somebody had parted out an L-4B and posted lots of parts from it.

I know that they don't officially support the 4 Line anymore, but you might contact Drake.  You never know what they might have left over.  I was totally surprised to find an original R-4A IF can there, brand new, in the late 90s.

I would also recommend posting a want-ad as many places as you can find to do so on the internet, so that the search engines will hopefully pick 'em up.  That way, if anyone is parting out an L-4B they might see it.

Those are great amps!  I hope you can find a meter...

Hmmm....did you take the meter apart and look for a broken connection?  Just a thought....

GL and 73

Tom AE5I
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VR2AX
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Posts: 589




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« Reply #4 on: May 31, 2008, 05:41:07 PM »

Tom,

Thanks for the suggestion. I will contact Drake in the coming week.

I did test the meter after I removed it and inspected the inside. Nothing obvious so I assumed the movement has gone. Maybe it is possible to substitute a movement from another meter in the old case, but I have not attempted that before.

The L-4 performs adequately and is a classic. I have rewired the on/off and cw/ssb switches with 12V bypass relays to bypass the AC current draw away from the switches, also irreplacable, to prolong their life. The power supply has been totally rebuilt completely except for the hv transformer.

Anyway, I will post back here later if I find a source of meters!

73
Wyn, VR2AX
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AE5I
Member

Posts: 124




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« Reply #5 on: June 02, 2008, 10:32:28 AM »

Hi Wyn-

Hmmm...  Hadn't thought of putting another movement inside the original meter's case, but that should work.  All you'd have to do is find one with a pointer that's long enough (you can always cut a long one off) and a sensitivity that you can use and then make some mounts for it (if necessary).  I'd definitely try that before giving up...

I wonder if the guts out of an L7 meter would work?

Best of luck to you on the project!

73

Tom AE5I
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VR2AX
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Posts: 589




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« Reply #6 on: June 14, 2008, 04:01:55 AM »

The L-4 is working again. Here's the infor in case anyone else has to go down this route.

1) Larson-Metercraft in California can supply a new meter. You have to fit your own dial to it so don't throw that away. They kindly emailed me the original 1966 Jewell spec and bill of materials for the L-4 Ia meter. Anyway, it was going to cost well over $200 with shipping to Hong Kong, so I searched for another solution.

2) Bought 10 MS2T original Honeywell meters on ebay (search Honeywell and MS2T on ebay). They are 50 uA meters, also have black pointers not red like the original and have a different dial. But at $50 plus $25 shipping for 10 meters decided this was the way to go.

3) The eBay meter is an exact reproduction for the original meters in the L-4 and L-4B (maybe MN2000 and W4?), except for the dial, range and black pointer. Remove the original dial from the old meter and refix on the new meter using double sided sellotape. You will nedd to remove the dial from the new meter, it comes away easily but take care not to damage the pointer when removing it.

4) Built a shunt network constructed n a very small daughter card, stock PCB/breadboard, that fits on the + side of the meter. Either side will do. To get calibration for 1A DC, I used a 1 ohm shunt (3 x 3 ohm 2W carbon composition resistors in parallel), with the meter in series with a paralled 47K fixed/47K trimpot combo.

5) Calibrated using my variable 0-15V bench suppply thru a 20 ohm 10W resistor and my Fluke meter. Cal was linear up to 0.7A which was the highest I could go.

6) After the usual dramas involved in fitting and soldering the thing in place, bug fixing, it works perfectly.

7) Cost of the components for the shunt network was less than $1. I spent arounf $4 in traveling to the various shops locally. Total outlay under $80. I also now have 9 spare meters of high quality in original Honeywell bags. Will lay down for my 2 L-4/L-4B and 2 MN2000 ( the MN2000 has a different front cover with black lower part, don't throw yours away).

Finally, thanks to all who responded in this thread. You really were a big help and inspiration.

Best 73
Wyn, VR2AX
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K7KBN
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Posts: 2802




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« Reply #7 on: June 14, 2008, 10:43:57 AM »

Great to hear the report, Wyn!

I guess HK has changed just a bit since I was there in the mid-1960s (US Navy).  I was invited to attend a meeting of the HKARTS, which was in the "Sergeants' Bar" of the old China Fleet Club.  Still have the eyeball QSL cards from about two dozen VS6s! "Peter Cheung, MBE", is one that stands out prominently.

"The Parisian Grill"!  "Jimmy's Kitchen"!  What great restaurants they were.

73
Pat K7KBN
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73
Pat K7KBN
CWO4 USNR Ret.
VR2AX
Member

Posts: 589




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« Reply #8 on: June 15, 2008, 03:06:01 AM »

Pat,

Little has changed in that respect. USS Kitty Hawk and her flotilla of pocket battleships are regular visitors here. Of course the young men, and now young women too, seem much younger. The China Fleet has gone but alternatives have sprung up!

Worth a return visit, you can still buy Japanese ham gear at around 15% less than US prices.

Cheers,
Wyn
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K7KBN
Member

Posts: 2802




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« Reply #9 on: June 15, 2008, 07:27:25 AM »

One big part of the picture you painted is sailing into the sunset.  Actually, from HK it's sailing into the sunRISE, but you get my point...

USS Kitty Hawk is on her way back to the States, where she'll arrive sometime in July or so.  She'll be decommissioned early next year.  I had hoped to remain in the workforce so I could participate, but I chose to retire a year ago.  I was stationed on the Hawk from '63 to '66, during which time I visited the BCC six times.

Other than USS Constitution ("Old Ironsides"), Kitty Hawk is currently the oldest active USN ship.  Kind of makes me feel proudly old! ;>)

73
Pat K7KBN
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73
Pat K7KBN
CWO4 USNR Ret.
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