Digital Panel Meters

[k4kyv]

Murphy strikes again!  The other night I was awoken by a clap of thunder about 3 AM, just as the bottom fell out. I got up and unplugged the computers but didn't have the ambition to venture out in the downpour to the shack to disconnect everything. The WX forecast had not indicated any probability of rain, so I had left everything plugged in. The storm passed through quickly and didn't seem particularly close, so I didn't worry too much about it.

This evening I got on the air, as the static seemed relatively low. No problem, till I noticed that the indicator meter on my remote antenna tuner wasn't indicating. I checked it out and looks like the lightning wiped out the industrial grade, 4" diameter 0-200 microammeter I was using  to indicate the remote  capacitor setting. Of all  the things, it had to get one of the two most irreplaceable and most expensive components in the entire unit. At least the no-stop 360° rotation precision pot survived. The regulator chip in the voltage supply, which I would have thought would have been the most vulnerable, wasn't damaged - too easy to find a replacement I suppose. There are two 30K precision resistors in series with the meter, and a diode across it, but the lightning pulse still managed to open the coil in the meter - it measures over 100k ohms.

I know an exact replacement meter would be pure unobtanium, and if I could find a new one it would probably cost hundreds of dollars. The original was a freebie out of an old TV transmitter. I think I'll go the route of a cheap digital panel meter.

Just wonder if anyone here has had any experience with those meters.  Since the indicator reading is an arbitrary scale, accuracy isn't terribly important, but it needs to be stable and reliable. A three digit red LED meter with 9v independent ground external power supply  runs about $14, and looks ideal if it maintains a stable reading. It appears to be large enough to be readable some distance away and cheap enough that it will be no great loss if lightning zaps it again. I just might order two, in order to have a spare on hand, even though Murphy's law says it will get the pot next time.

This company seems to have what I need, but I can't find any information on shipping and shipping charges.  Not sure the merchandise is even shipped from a N American location even though they show a US address, and don't want to be hit with an exorbitant shipping  charge and two-month wait.

http://www.futurlec.com/Panel_Meters.shtml

[K5UJ]

That's one of the thinks I dread--going to bed with everything connected and being woken at 2 or 3 a.m. to the rumble of thunder.
I've done that running around in the rain disconnecting feedlines outside thing too.   We're supposed to get another wave or two of storms this morning.  One thing I look forward to about having all vacuum tube gear is that I expect it is a bit more resistant to damage from transient discharges.  My problem now is all the solid state gear I have that would be expensive and/or impossible to replace.  I'm thinking chiefly of the audio processing boxes.

I thought about firing everything up last night and wish I had but I was so tired from work I passed.  I will look through my pile of meters and see if I have a uA meter.  I wondered how often your tower gets hit Don.

Rob

[K5UJ]

I found this one.....sorry about the blurry photos.  it is a Simpson 0 - 200 uA meter scale model 29

[flintstone mop]

Sorry about the problems Don.
I get those surprises too, but have made it in time to disconnect the antenna feeds.
All of the storms are back, as the huge high pressure dome that dominated the WX is gone, there have been some close strikes here.
You have to go out to the shack to disconnect antennas or were you disconnecting the A.C.?
I dislike digital meters when you are "tuning" something. The time lag from the change and actual indication of change sux.

[The Slab Bacon]

Lightning hits do some really wierd stuff, and sometimes it makes absolutely no sense what gets destroyed.

I took one a few years back. It hit the pole light on my garage. Totally missed all of my antenners. The pole light is only about 10' off of the ground.

Blew out my phone modem and flatbed scanner on the compooter, but the rest of the 'puter was ok, go figger? ? ?  ? ? ? ?

Took out the answering machine, a couple of CFL lights, the antenner relay output bypass caps on the Valiant (charred to ashes), my alarm clock, and a bunch of other totally unrelated stuff throughout the house, and the pole light of course.

Lightning does do some strange stuff....................

[k4kyv]

I already have several other microammeters, but the blown one has a square front, and fits into a 4" round hole, one of those with the needle pivot centred right in the middle, and the scale covers about 270° of rotation. Like the ones you see on the instrument panels in the control room of a chemical plant or refinery - easily viewable from 10' away. A damned shame; it looked really nice in the black wrinkle 19" rack panel I custom cut, drilled and painted. Spent a lot of time constructing the unit, and the damned thing didn't even last a year. I'll probably go the route of a digital panel meter mounted on a small bakelite sub-panel to fit over the hole, rather than an off-size meter JSed in place of the original one. Actually, a 0-20 voltmeter would work better, since I used a couple of 30K precision series resistors to convert the microammeter to a 3000 ohms/volt voltmeter.

I have another meter of identical construction, but it is 0-5 amps. I may take it apart, remove the internal shunt and see if the basic movement is 0-200 μa or less, but I suspect it is more like 0-1 ma or 0-10 ma.

I normally disconnect everything before leaving the shack, but forgot that night, and with no rain or storm activity predicted I didn't bother to go back out to the shack. The lightning pulse was evidently induced into the cable running from the tower to the shack. The loudest clap of thunder didn't even sound that close. I was aware when I built the thing that lightning would be a problem, so I made up a quick-disconnect that completely disengages the multi-wire  cable from everything else. I have lost countless answering machines and cordless phones to lightning, plus that is what finally did in my old computer. I use a large, open, exposed DPST, knife switch on the shack wall to kill the power to all the station equipment when it is not in use, so power line surges are not a problem unless they occur while I actually have the station running.

This is why I would never even consider setting up an unattended remote controlled station like W9AD does from Chicago, and operates from Mexico. The lightning we get here would most likely destroy the entire station during my first trip.

[K5UJ]

Hi Don,

you weren't kidding about that meter being unobtainium.  I can tell you without even looking around that I don't have any meter like that.  In fact, I don't recall ever seeing one like that in any flea market.   It looks more like some kind of water pressure gauge.  I hope you can use that other one you have with the right shunt.

[W7TFO]

Hi Don,

PM me, I have a few of those here...

Flickering digits suck, stay analog.

73DG

[w3jn]

 

Now THAT'S a meter collection!

[WQ9E]

Don,

You could build a SS meter amp if your replacement meter movement is of lower sensitivity. 

[WB6NVH]

Futurlec has a US office but they ship from Asia.  I seem to recall shipments arriving from Taiwan generally, although I think a more recent one was from Thailand.  Shipping rates seem quite cheap and are listed on their site under Corporate-->Delivery over on the left sidebar.  I have seen some complaints about lengthy delivery times but the stuff seems to always get there in the end.  I have also seen some statements that the stuff arrived faster than a USA-based shipper.

Those GE meters were quite common in large industrial applications back in the 50's and 60's, not radio gear, hence they might seem unusual unless you have worked in a power station or a mill, something like that.

[W7TFO]

The AB-40 (a GE designation) standard meter was made by a lot of different companies, like Westinghouse, GE, API, and Weschler.

Westinghouse used them in their BC transmitters:

Indeed, some of the toughest meters in the world, other than lightning surges.

73DG

[W2PFY]

Dennis, that link just showed an old radio???

[W7TFO]

Link is to a photo of a vintage Westinghouse FM transmitter.

73DG

[KB3DKS]

Nice black background with white print faces! Nice contrast. The old Westinghouse Mil CAY series and others used that same white on black.
 Your posted link has som junk buried in the middle. If you go to the link in the browser after it after the site comes back you can cut it out to get to the intended pix. Otherwise it just gets you to the site home page pix.

Bill

[W7TFO]

Got me about the polluted link.  I posted the pix in my earlier reply.

73DG

[Opcom]

Hi Don,

PM me, I have a few of those here...

Flickering digits suck, stay analog.

73DG

WOW!! Pretty!

[W2PFY]

I have an original sales brochure for the FM3. It used two WL5736 tubes in GG that are the same tubes used in my Westinghouse MW-2. There was one in use in Maine until the early 1970's. Too bad it hit the junk pile! Tim, WA1HLR worked on it. He had to go in the basement to work on something down there. There was four feet of water in the basement and he had to walk on a beam to do his work above the water.

[kg8lb]

The AB-40 (a GE designation) standard meter was made by a lot of different companies, like Westinghouse, GE, API, and Weschler.

Westinghouse used them in their BC transmitters:

Indeed, some of the toughest meters in the world, other than lightning surges.

73DG

"Power House Style" meter is what they called them at work.
  We used the same style meters at Sun Electric back in the late 70s and early 80s. The Sun Chassis Dynomometers used them as well as some of our transmission test cells. When we closed the Industrial Systems Division they had about a hundred of them to scrap. I brought a few home ,gave away a few but there was little interest in them from most hams.  There may be a box of them in the attic. Will take a look later.

  Then again, with a little surgery it would be very easy to adapt and re-use  the present DOA meter. Use a motorized servo similar to an RC servo and drive it with a simple servo amp. Save the "look" and have an easily maintained system .

 If you care to go digital I can send you some stepper motors that are used in present day autos for speedo/tach/fuel instrumentation. Excellent resolution and easy to drive with a simple PIC application. The steppers are compact and quick, mount easily and have a post output shaft easily adapted to the meter's pointer. Should be very easy to install in the meter housing.



This one is a 200 uADC meter:
http://www.ebay.com/itm/Yokogawa-Ammeter-103111EAEA7XTW-BD40-0-201-2-UADC-NNB-/350388268665?pt=LH_DefaultDomain_0&hash=item5194c4ae79

[k4kyv]

Fixed the remote tuning indicator unit, thanks to the 200 µA drop-in replacement meter sent by Dennis, W7TFO.

The  only hassle is that I will have to re-do my tuning chart, since this meter scale is 0-150 and my old one was 0-200. A simple matter of multiplying each number on the chart by (0.75).

Dennis has a cabinet full of that style of meters, in case anyone else needs one. He asks to please PM him for further info.

[W7TFO]

And the "PSIG" designator was custom, of course.   

Point Something In General (Direction).

73DG

[KA2DZT]

Don,

You can never have too many meters.

Lucky Dennis had the exact style ever though the scale was different. NBD just recalibrate.  I guess the best scale would have been 360 or 180.

On second thought,  I'm thinking you may have to change the amount of current through the meter to match the rotation of the capacitor.  Full rotation of the capacitor equals full scale reading on the meter.

Fred

[k4kyv]

On second thought,  I'm thinking you may have to change the amount of current through the meter to match the rotation of the capacitor.  Full rotation of the capacitor equals full scale reading on the meter.

Full scale reading on the meter is 200 μA, same as the old one.  Just the numbers printed on the scale are different. I would have been perfectly happy with a 0-100 scale, the same as the tuning dials on the transmitter.  I assume the "PSIG"  written on the scale means pounds per square inch gas pressure.

[K5WLF]

PSIG is PSI (gauge) or pressure relative to atmospheric. PSIA is PSI (absolute) which is gauge pressure plus atmospheric pressure.

ldb

[KA2DZT]

On second thought,  I'm thinking you may have to change the amount of current through the meter to match the rotation of the capacitor.  Full rotation of the capacitor equals full scale reading on the meter.

Full scale reading on the meter is 200 μA, same as the old one.  Just the numbers printed on the scale are different. I would have been perfectly happy with a 0-100 scale, the same as the tuning dials on the transmitter.  I assume the "PSIG"  written on the scale means pounds per square inch gas pressure.

Don,

No reason why you can't change out the meter faces.  I've done it many times.  Just work on a dust free surface.  Although, some meters are sealed and can not be opened, not sure what yours is.

You may be able to even repair the open in the old damaged meter.  Take a look inside, doesn't hurt to give it a try.  I've repaired a number of movements including replacing the springs (not work for shaky hands).

Fred