snow brings out amer's

[N3DRB The Derb]

I just tuned thru the ghetto a while ago n counted 5 qsos between 3870 and 3890. Quite the pileup.

I am getting rid of some JS in my ground distribution system and the top has come off the matchbox again. Wont go back on until the damn internal swr meter works at any power level. I have to shield the meter housing somehow, the rf in the box is driving it crazy. the fact that it does not work is driving me crazy.  

this meter came out of the seperate swr meter Johnson sold, and it doesn't have the copper shield on the back like the factory units did.

[w8khk]

Hi Derb,

I pulled the meter shield from my Valiant when doing other mods, and I do not intend to use it.  If it would fit your meter, you may have it.  I can measure the shield, or you could measure your meter.  Need diameter behind panel, depth of meter housing behind panel, and spacing between connector posts.  Or you could take it and mod it as needed. 

73, Rick

[N3DRB The Derb]

lemme go snap a picture of it. should be able to tell on your end if it will work. it has 2 holes for the meter post terminals with rubber grommets to prevent contact yet allow the screws to hold the shield in place.

[w8khk]

Derb,

I dug the meter shield out of my junkbox.  It is made in two parts, a flange that mounts behind the meter, then the other part slips into the flange and uses the grommets to hold it by the meter posts.  The meter used three machine screws to mount to the panel.  I will send the grommets if you like, but they are not very good.  I think the original Johnson implementation used fiber grommets, with a step to keep them centered.  When I disassembled the rig, it had neoprene grommets cut in half - they will work but in my opinion they are hammy hambone and difficult to center properly.  Considering the number of screws in the flashbox cover, you will probably want to do it better anyway.

Meter hole is 2-1/4 inches diameter.
Overall size of shield is 3 inches diameter.
Depth clearance front to back is 1-1/2 inches
....but could stretch to 2 inches if not fully inserted in flange.
Meter post holes are spaced 1 inch on center, but new holes could be drilled.
Holes are not offset, but centered on the meter vertically in horizontal plane.

If this works for you I will send it with the terminal strip and chokes that were mounted to the back of the meter shield.

73, Rick

[N3DRB The Derb]

ok rick, I'm having a bit of trouble getting it apart. My left hand is telling me it's had enough use for the day.  It's protesting, better stop.

I think it would be prudent for me to continue in the morning. I'll measure and post the pics then and you can compare. Thanks for going though the trouble. 

[w8khk]

Hope you feel better, Derb!  No hurry, if you would like a pic of the shield parts, just let me know.  Hope this will help your flashbox work betta.

I still have to replace two relays in my Valiant, but so many other things have kept me from it.  When it is finished, hope to work you soon!

73,
Rick

[WA1GFZ]

I think the shield is about the size as a large tuna fish can. 

[N3DRB The Derb]

yeah thats right. I've seen one, looks like a large copper tuna fish can with finger stock on the open end and 2 grommeted holes for the meter terminals to pass through - shield held in place by the meter terminals when the nutz are screwed down. Without it the meter is quite useless. The external swr unit doesnt need it of course.

[w8khk]

Hi Derb,

I know you are busy with antenners, etc....  The meter shield is sitting on my desk, and I will send it if it will work for you.  No hurry, jus wanted to let you know I haven't forgotten about your tuna project.

73, Rick

[N3DRB The Derb]

Rick, I'll go get the camera and upload pix of the back of the meter for you.

here ya go. should give you an idea of what I have. I can make measurements if you need them.

[w8khk]

Thanks for the pix, Derb.   The main issue is the diameter of the back of your meter.  If it is greater than 2-1/4 inches, the shield will not work.

Your meter has 4 mounting studs, while this shield has three.  Should be no problem for you to blast new mounting holes.  Your meter terminal posts are a bit short for normal mounting, but you could use feed-through capacitors on the back of the meter shell, should work fine.

Before going to the trouble of shielding the meter, you might just try grounding the foil shield lead of the cable at the meter, see if that helps.  Let me know if the size is right, and I will get the shield in the mail.  Thx, and 73, Rick