The AM Forum

Things are coming along nicely, I am basically done with the 4 modules and all of the parts. Essentially I need to build from the output of T1 to the RF output. I am starting to think about the front panel. I notice on Steve's schematic he specifically says to put your drain bus meters at the modulator. Is there any reason why I shouldn't or cant mount them at the RF deck? Also I love me some metering, any negatives to having a volt and current meter for the drain supply?

The main reason to put the meters in the modulator is so that you may have two or more RF decks on multiple bands, sharing the same modulator, so you will not have to purchase meters for each RF deck.  it is simply a matter of economics.

On the 24-FET transmitter I'm building, I'm mounting the 4 drain current measuring shunts along with one for measuring total IXDD driver current on the RF deck. To save space I'm mounting them vertically. I think they all cost me a little over $20 shipped from China. The 75mV meters are about the same cost.

In my opinion, mount away!

Jon

Actually, here's what I'm going to do for my meters. They'll be mounted in a 4" channel from Home Depot and have a blue LED strip to illuminate the meters. It's meant to be remote and sitting by itself, but I'll set mine next to the transmitter.

Jon

How will you make the holes for the meters? I look at nibblers but they are not easy on thick (1/8") panels, or more likely, my hands don't like a lot of linear inches nibbled a tiny bit at a time.

This is the material I was thinking of. It’s thin and would reflect light pretty well. I’ll weld up a frame for it to be mounted to since the metal is flimsy like tin.

Jon

Those are steel 2x4.  Used in commercial construction.  Typically 22 to 26 gauge

They can be cut with tin snips and chop saws with the appropriate blade.

You'll be fine with a nibble in that. I agree with using a backup or other piece of metal for rigidity.... Otherwise they REALLY flex.  One of those things where individual parts suck, but the system is really strong kind of things.

--Shane
KD6VXI

There is no particular reason to put the meters on the modulator other than the fact that you only have one set of meters to calibrate.   And the RF amp can be smaller (which for me is a factor).

Otherwise, in theory, they can go anywhere.

I finished welding the frame and mounted metal stud to it. I ordered the 7 meters that'll be mounted there and the blue LED strip.

Jon

I painted the panel black and mounted the LED lights. I'm just waiting on the meters to arrive.

Jon

Looks good!

I mounted the meters and shunts in the RF deck, more because there was space in the RF cabinet.  I also think it better to monitor each module and would prefer one wire pair to feed the deck (DC) rather than 4.  I bypassed all wires going in/out of the RF deck, the fewer the better.

~ps

The meters arrived! 

Jon

UV!

I like the lights in the meters!  Is that stock, or did you add that ?

Oops, guess I answered my own question - you did the lighting.  Very nice.