Had some fun today......

[guitar_199]

Got in here and finished my RF sampler for my test bench. It is certainly no "gold standard" but it is generally within 1 db from about 3.0 MHz to about 40 MHz..... plenty good enough for me.

Here are the insides....

and here is what is working for the first time ever...

the old Boonton 102F handles the RF generation for the receive side and it is working as well.

I don't know how to act......

 

[TheRealPorkchop]

Parts list, instructions and where you acquired your parts please, for scientific reasons, ya know...

 

[guitar_199]

First order of business, this link is to the PDF that I used as the basis for this whole thing.

http://www.collinsradio.org/wp-content/uploads/2015/05/Build-a-Quality-RF-Power-Sampler-Jackson.pdf

That said, in my opinion, it makes it look a little tougher than it is in reality.

Let me follow up in a short bit with some more photos and I'll put some explanations with them.

I'll also dig up the links to what parts I bought (if I can find them!)

Parts list, instructions and where you acquired your parts please, for scientific reasons, ya know...

 

[guitar_199]

I apologize for stringing this out....but I am trying to apply some order to how I send all of this....

First, the parts I used.... (sorry I could not find a way to put links in. They kept getting changed to some MEDIA type that did weird things!!!)(I tried again and it seems like any time I put a link that goes in to Amazon... gets changed when I make the post.)

So.....first the Amazon Parts

Then, some special resistors I ordered from Mouser and these are fairly critical. More explanation to come....

On these resistors I ordered spares more than I needed because they were cheap.

Parts list, instructions and where you acquired your parts please, for scientific reasons, ya know...

 

[guitar_199]

One of the things that was confusing to me was the "Faraday Shield" part. Not so much what it was doing....but how they implemented it.

This pic says it all....

All that is is a short piece of RG-58 just long enough to bridge between the tip connections of the So-239s. What is important is that I cut the cable to length, then stripped off the jacket, THEN slid the shield off of the wire. then I stripped the wire ends so that they were ready to solder in place. then cut the shield to where there was about 1/8" of wire insulation sticking out at each end and slid it back on to the wire. Then...AT ONE END ONLY... I soldered on a drain wire for the shield... long enough to reach the BNC. Then I took some PVC pipe tape...(plumbing type) and wrapped it around the sheild, then slid the toroid transformer core on to the shield.

Note that: The end of the shield that has the drain wire soldered on.... establishes the INPUT. So the transmitter feeds that SO-239 and the other goes to the dummy load.

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

the magic resistors......

The three resistors are 10 ohm 1%, 47 ohm 1%, and 270 ohm 1%.

I took this straight out of the PDF.

The 47 and 270 paralleled together are 40 plus a little extra... very close to 40 ohms.
What you see in the picture.... the 47 and 270 are soldered together, one end soldered in the BNC. At the other end, the 10 ohm joins them...and goes to ground.

The two transformer leads go to each end of the 10 ohm. (So one lead essentially goes to ground and the other at the joint of the 40 ohm (pair) and the 10 ohm.
That's it!

So in my mind it was easier to do than this PDF makes it sound.....

But...the key is....

for CLOSE TO -40 db, the toroid gets 10 turns of the wire.....
for CLOSE TO -50 db, the toroid gets 32 turns of the wire...