Measuring Return Loss and SWR with a HP 415E, HP 778D or HP 8470B

I was asked to show how to use the HP 415E meter from my 415E Perf Testing video ( • HP 415E SWR Meter Perf... ) and while thinking about it I decided to expand the scope a bit to cover measuring return loss and calculating SWR with a few other pieces of HP test gear. You can measure return loss with an SWR Bridge, a dual directional coupler such as the HP 778D or via a HP 8470B Crystal Detector.
The AT&T Archives video is located here:
• AT&T Archives: Similia...
W2AEW's Visualizing RF Standing Waves video is here:
• #208: Visualizing RF S...
[BTW you should subscribe to his channel]
Finally, CalESG's video on a slotted line lab is here:
• Slotted Line Lab

[@TheJHSound]

Great Video! Thank you for creating this awsome content and giving the hint on the AT&T Archives Channel. The Similarities of Waves Video is just great

[@tgsoapbox]

Glad you enjoyed it - I've spent hours just browsing through those AT&T videos - They're simply outstanding.

[@PelDaddy]

Thanks for sharing. Love the old classic gear.

[@tgsoapbox]

Glad you enjoyed it. It's good to see this stuff still working and being really accurate.

[@ismarudinalkadri5639]

PelDaddy q11

[@ovalwingnut]

Always interesting 👍😎
A bit over my head (but so was my first GF in Jr. High:) but that's what makes this a mega-uber learning event for me. Enjoy the style of the videos and your xlint post production choices and decisions. Like pizza. I just can't get enough.

[@tgsoapbox]

Glad you're enjoying the videos - I ended up acquiring a slotted line so you should check out that video as well.

[@adeletanner2262]

Thank you for an excellent video. As a 50+ year amateur radio operator I've spent countless hours building antennas of various types and obviously dealing with SWR, using different SWR measurement device technologies over the decades. I must admit, however, that I am at loss in seeing the best practical application of what you are doing here... Testing cables? Circuit losses? UHF antennas? Can you please educate me as to what the best practical use of this test equipment is? Thank you much and best regards!

[@tgsoapbox]

Hey Adele, thanks for watching - At their time these were the gold standard of measuring SWR/Return Loss. They can do everything you mentioned with a degree of accuracy that was unmatched outside of Network Analyzers - The additional benefit is that they could extend up to very high frequencies that you might not have direct measurement tools available for.
Today all this stuff has commercially been replaced with Vector Network Analyzers and in the hobby market by things like the NanoVNA - The video was really just an example of how to do it with this old kit rather than showing something that was unique - Let me know if that doesn't answer the question.

[@davideisenberger6197]

Thank you for taking your time to make this excellent video! My question is shouldn't you have checked the Directivity of that smaller coupler first? And for some reason, it "appears" to me that were only seeing the Return loss of the load? 73's David

[@tgsoapbox]

Hey David - Thanks for the comment and taking the time to watch the video. This is a great question and I didn't cover it in the video. To measure the directivity on an ideal 3 port device you would measure the return with an ideal short on the DUT port and then with an ideal load. The difference in the two values is the directivity of the coupler.
Seeing that ideal is impossible, the measurement will have errors from the internal load, the external load, the short and the sensor. I should have shown using the proper load (SWR of 1.05 to 4 Ghz) and the short to prove that directivity was greater than 20dB (this is a rule of thumb for directional couplers). I didn't do that, sorry, I took that for granted.
Doing the measurement however shows that the RL of that BNC load corresponds to an SWR that was close to what my VNA measured so it implies the coupler directivity was good enough.
Does that answer your question?

[@TAC19jm]

very good！！

[@tgsoapbox]

Thanks - Glad you enjoyed it.

[@yenaurapourtoulmonde]

11'45" for introduction! Don't you think this is much too long?

[@user-uv4xe3cq2y]

It's hard for my eyes to focus on objects darting in and out of range of the camera, objects like sensors, papers etc. It tends to disorient me. Otherwise, thanks for your video.

[@tgsoapbox]

Thanks for the feedback - Will try to slow down a bit.

[@kayclaydancesupply1933]

I always cring when I see someone rotate the standard and not the nut. Doing so wears off the plating. Hold on standard and rotate the nut!

[@tgsoapbox]

Yes I know, for whatever reason I'm just not always great on that - It impacts the connector and shouldn't be done - I know this and yet I still do it...