RFS DragonSkin & GD&T? Toughbook vs Dell Rugged? 7 RF Questions From the Field

I’ve spent roughly eight years specifying and installing RF transmission line systems—mostly tunnels, transit depots, and public-safety radio projects. This article answers questions that actually came up during a 2024 radiating cable replacement: RFS company names, DragonSkin cable, GD&T callouts, the 117 multimeter in my toolbag, and the Toughbook vs Dell rugged debate. If you’re about to order similar gear, I hope these notes keep you out of the same trouble.

The topics are in the order I’d ask them before a project starts: Amphenol/RFS legal entity, DragonSkin cable, the GD&T confusion, connector tolerances, the 117 multimeter, Toughbook vs Dell rugged, and the installation mistakes checklist.

1. What is RFS Inc.? Is it the same company as Amphenol?

RFS stands for Radio Frequency Systems. Back in 2019, Amphenol completed its acquisition—I remember the letterhead change more than the exact date. That’s why you’ll now see “An Amphenol Company” near the RFS logo, and why some quotes or invoices arrive with both names.

Here’s the part that cost us two weeks. I wrote “RFS Inc.” on a purchase order, but the supplier’s legal entity in our system was Radio Frequency Systems Inc. The invoice didn’t match, accounting put a hold on it, and a pallet of connectors sat in receiving while payment was stuck. Now I check the legal name on the quote before creating a PO. It’s boring, and it saves a week.

2. What is RFS DragonSkin cable?

DragonSkin is the RFS cable family that includes flexible radiating cable—what we still call leaky feeder. You run it along a tunnel, mineshaft, or large building corridor and it radiates signal along its full length, which makes it useful where you can’t install a regular antenna every 50 meters.

From the outside it looks like flexible coax, so crews used to standard corrugated feeder tend to treat it the same way. The reality is different. Radiating cable has intentional slots and a construction designed for flex; crush it, pull it against a sharp edge, or bend it past its rated radius, and the RF damage may not show up in a DC measurement. Read the RFS datasheet for the exact DragonSkin product. Attenuation and coupling loss values are product-specific. As of January 2025, I still check the frequency column on every new part number instead of trusting “this one is the same as last project.”

3. RFS GD&T? What does RFS mean on a drawing?

This is one that makes people think I’m joking. Search “RFS GD&T” and you get two different answers: RFS-brand datasheets, and ASME Y14.5 tutorials where RFS means regardless of feature size. Both are correct. Context matters.

On a connector drawing from RFS, the company name sits in the title block. Inside a feature control frame, though, RFS means the geometric tolerance applies regardless of feature size. Under ASME Y14.5-2018, when there’s no material condition modifier such as “M” or “L” shown, the default is RFS—no bonus tolerance just because the actual feature departs from maximum material condition.

I once assumed every “RFS” on a drawing was a brand mark. I was wrong, and a part came back with a position tolerance interpreted at MMC instead. We only caught it during first article inspection. The letters near a diameter symbol or inside the tolerance block are not a company stamp.

4. Why does GD&T matter on RF connectors?

Because an RF connector is two things at once: a mechanical part and part of the transmission line. If the center pin’s true position drifts relative to the outer conductor, the air gap changes, the characteristic impedance changes, and return loss gets worse. At higher frequencies, tenths of a millimeter show up in the measurements.

This matters when you order connectors from one manufacturer and cable from another. “It will mate” is not the same as “the interface tolerance is verified.” On transmit systems, a marginal connection can also create passive intermodulation, which is one of the most expensive problems to chase on a tower. So yes, GD&T on a connector drawing looks like paperwork—until the day it’s the reason your sweep passes instead of failing.

5. Can I use a 117 multimeter to test an RFS cable run?

I still carry a Fluke 117 multimeter. It’s a great meter for building electrical work. But it’s not an RF test set, and it will not tell you whether a radiating cable or feeder run is actually good.

In September 2022, I signed off on a radiating cable run because continuity looked clean on the 117. The return-loss sweep later found a crushed section about 40 meters from the feed point. The DC path was fine—the inner conductor was still continuous—but the impedance around the crush wasn’t. A good portion of transmit power reflected at that point.

The 117 cannot measure VSWR, return loss, insertion loss, or coupling loss because it has no RF source. It’s built for electricians: AC/DC voltage, resistance, continuity. That’s all. Use a calibrated cable and antenna analyzer for the RF sweep, and keep the multimeter for DC checks. One does not replace the other.

6. Toughbook vs Dell rugged: which one should RF crews carry?

I’ve used both on actual site work, so I won’t pretend one brand is always the answer. In 2024, a Toughbook survived a drop down an access hatch with just a cracked corner. A Dell rugged unit spent a season in a service truck and never missed a beat.

From the outside, all rugged laptops look like tanks. The real difference is configuration, weight, and service. Panasonic tends to keep legacy ports and long-term replacement parts available, which matters when you need serial connectivity for older radio infrastructure. Dell rugged hardware tends to cost less, weigh less, and feel easier for an IT department to manage.

My opinion: if the laptop mostly lives in a truck and an office, buy Dell rugged and put the savings into spare batteries. If it’s carried in the field every day, the Toughbook’s durability and service package is worth the extra money. The firm advice I’ll give either way: compare service turnaround time. When your only laptop is dead, five days without it costs more than the price difference.

7. What are the most common DragonSkin installation mistakes?

I’m including myself in the “we” here. In November 2023, we terminated 32 radiating cable ends on a transit project, and 14 failed the final sweep. Connector kits had to be cut off and redone. The cost was roughly $3,200 in parts—I’d have to check the exact chargeback—plus a week of schedule.

The root cause was a bad assumption. We used a prep tool meant for standard corrugated feeder because that’s what the crew had always used. DragonSkin is a flexible radiating cable with a different construction, and it needs its own connector system and prep procedure.

Here’s the checklist that now lives on our whiteboard:

• Confirm the exact DragonSkin part number and order the connector kit designed for that cable family.
• Read the connector assembly drawing—strip length, insertion depth, torque—instead of working from memory.
• Check the GD&T block on the interface drawing, especially true position of the center contact.
• Use the approved prep tooling with fresh blades. Don’t borrow the tool from another cable line.
• Inspect the connector interior for shavings or debris before assembly.
• Torque the coupling nut to the documented value with a calibrated wrench.
• Do a return-loss sweep before sealing everything up. Use the 117 for DC sanity only.

It looks like a lot, but the full check takes about five minutes per connector. Cutting off and redoing a bad termination takes much longer. I know, because I’ve done it.