Tag Archives: Cable Assemblies

Antennas, Guest Posts, News, Portable, QRP, Radio Field Craft

Comparing Coaxial Loss in RG-58 and RG-316

40 Comments

by Eric, WD8RIF

I recently decided that I would operate portable during the upcoming ARRL 10 Meter Contest and would combine this operation with a pair of Parks on the Air (POTA) activations, one on the Saturday of the contest and one on Sunday. While putting together my field station for this, I realized I wanted to see how lossy my RG-58 and RG-316 feedline cables were on 10m. Yes, I could have resorted to online charts of feedline losses, and I know that the RG-316 is lossier than the RG-58, but I thought it would be fun and more enlightening to make actual measurements, to empirically determine the losses in my particular coaxial cables.

The two coaxial cables in question are both 25′ in length and both are equipped with BNC male connectors on each end. The RG-58 cable is a high-quality cable that was originally manufactured to be a 10Base2 ethernet cable, but it’s probably now over twenty years old. The RG-316 cable was recently purchased from Tufteln (link) and includes an RF choke near one end.

To make my measurements, I used my Elecraft KX2 (link) to generate RF into an Elecraft DL1 dummy load with RF detector (link), using a digital multimeter to measure the voltage at the DL1’s measurement points. I used the formula that came with my DL1 assembly instructions to calculate the measured wattage:
P = (((V x 1.414) + 0.15))^2)/50

I made measurements in the CW portion of the 10, 15, 20, 40, and 80m bands, with the KX2 set at 5 Watts output.

My first set of measurements was made with the DL1 connected directly to the KX2’s antenna jack using a BNC union:

Direct (no feedline)
Band Volts Watts
10 11.62 5.498
15 11.59 5.470
20 11.61 5.489
40 11.63 5.508
80 11.63 5.508

My immediate observation was that the KX2 appears to be generating more than 5w when it is set to be producing 5w but also that the KX2 output is essentially same from 10m through 80m.

My second set of measurements was made with the DL1 connected to the KX2 through the RG-58 cable:

Direct RG-58
Band Watts Watts
10 5.498 4.809
15 5.470 4.844
20 5.489 5.004
40 5.508 5.184
80 5.508 5.276

My third set of measurements was made with the DL1 connected to the KX2 through the RG-316 cable:

Direct RG-316
Band Watts Watts
10 5.498 4.190
15 5.470 4.322
20 5.489 4.507
40 5.508 4.774
80 5.508 4.959

I was pleased to see to see that both the RG-58 and RG-316 behaved as I expected them to: the loss increased with increasing frequency.

Using the magic of MS-Excel, I created a table of Loss in Watts for both cables, relative to direct connection and to each other:

Direct Difference (Loss) (Watts)
Band Watts RG-58 vs
direct		 RG-316 vs
direct		 RG-316 vs
RG-58
10 5.498 0.690 1.309 0.619
15 5.470 0.626 1.148 0.522
20 5.489 0.485 0.982 0.497
40 5.508 0.324 0.734 0.410
80 5.508 0.232 0.549 0.317

In looking at this table, it was immediately obvious that RG-316 is much lossier than the RG-58, particularly on 10m. By looking at the row for 10m, one can see that I am losing nearly 0.7 watts in the RG-58 but I am losing over 1.3 watts in the RG-316.

For completeness, I added columns for Loss in dB to the spreadsheet:

Difference (Loss) (dB)
Band RG-58 vs direct RG-316 vs direct RG-316 vs RG-58
10 0.582 1.180 0.598
15 0.528 1.023 0.495
20 0.402 0.856 0.454
40 0.263 0.621 0.358
80 0.187 0.456 0.269

This exercise showed me that for my upcoming ARRL 10 Meter Contest POTA outings, I would do best by connecting my antenna directly to my transceiver, if possible, without using either coaxial feedline. If conditions at the operating site require me to use feedline, I will chose the RG-58 over the RG-316.

The tables also tell me that RG-316 is pretty lossy regardless of the band; for my regular field operating, unless I’m planning to do bicycle- or pedestrian-portable operations where weight and bulk is a consideration, I’ll carry RG-58 instead of RG-316. (I purchased the RG-316 specifically for bicycle- and pedestrian-portable operations, and I plan to continue to use the RG-316 for those applications.)

At some point, I will repeat this exercise with RG-8X, a feedline that is very close in size to RG-58, is less lossy, but is also heavier and stiffer.

Accessories, Field Reports, Morse Code, News, Portable, POTA, QRP, Reviews, Videos

POTA with the Penntek TR-45L and importance of quality cable assemblies!

5 Comments

On the morning of Wednesday, June 14, 2023, I left the QTH with a goal in mind: fit in a POTA activation before taking my sweet mom to an appointment that afternoon. As I’ve mentioned in the past, there are about four park options that are easy detours off the 1.5 hour drive to my parents’ home, so it was very much doable.

I decided to go to Tuttle (K-4861) since it would be very close to one of my favorite lunch spots (Food Matters in Morganton). I figured I could fit in an activation, then grab lunch after, and still make the appointment with time to spare.

In almost every case, this is how I do POTA these days: it’s all about fitting in activations with weekly travels and errands. It’s rare that I simply plot out an activation or two the day before. More often than not, I schedule my activation a max of 30 minutes before I arrive at the park.

I arrived at Tuttle around 11:30 AM and had the park to myself. There were no other guests there, just park rangers. And lots of birds.

PSA: Buy/Build quality cable assemblies!

A couple days prior, I received a cable assembly sample in the post: a 25 foot RG-316 cable with BNCs on both ends and three series 31 in-line ferrites from ABR Industries. These slim in-line chokes are a new option ABR is offering, hence the reason they send me the assembly.

I speak about this at length in my video below, but I’ve been a customer of ABR Industries for well over a decade now. ABR is a USA supplier of high quality cable, cable assemblies, and other cable components. I’m a huge fan. In fact, I wrote about them separately on the SWLing Post a couple years ago.

Full disclosure: ABR Industries sent me this cable assembly (and one other I’ll feature in a future report) free of charge. They are not a sponsor (although I’d love for them to be) and I’ve no other relationship with them other than being a customer.

I go into greater detail in my video, but I learned a while back just how important it is to use high-quality cable assemblies, adapters, and connectors in the field and at the QTH.

As a field operator, I know my cable assemblies are essentially consumables. With all of the winding, deployments, packing, being outdoors, rough handling, etc. they will eventually fail. (In fact, Alan made a point of this in his latest field report when a mishap in the field broke a good assembly.)

High quality cable assemblies will not only provide better longevity and better durability, but also less loss and overall higher performance. It’s worth the cost because when I hike to a summit, the last think I want to discover is that my cable assembly has failed.

Note that I also build my own cable assemblies (indeed, I feel like all radio ops should learn this simple skill) and try to use quality components and best practices to make the best assemblies I can.

Take-away is: don’t skimp on your cable assemblies. I no longer buy my cable assemblies from random suppliers on eBay or Amazon, I buy them from companies that build and test their assemblies within our hobby; companies like PackTenna, Tufteln, Messi & Paoloni, and ABR Industries.

Here ends my PSA…let’s get on with the activation!

Tuttle Educational State Forest (K-4861)

I spent quite a bit of time talking about cable assemblies, then I moved straight into setting up my field gear. I launched a line and deployed my cannibalized 40m EFHW again and connected it to the Penntek TR-45L. Continue reading POTA with the Penntek TR-45L and importance of quality cable assemblies! →

Antennas, Morse Code, News, Product Announcements

QRPer Notes: Simon’s World Map Update, RG-316 Assemblies, My-Key-Mouse (USB), and Canary Islands VCAN

5 Comments

Because I receive so many tips from readers here on QRPer, I wanted way to share them in a concise newsletter format.  To that end, welcome to QRPer Notes, a collection of links to interesting stories and tips making waves in the world of radio!

Simon’s World Map

Many thanks to reader, Mike Bott, who notes that Simon’s World Map has been updated to V1.2.3.

Click here to download Simon’s World Map.

RG-316 BNC to BNC assemblies

Don (W7SSB) shares two announcements.

First, he notes that Chameleon Antenna is now selling RG-316 assemblies with in-line RF Choke options and BNC fittings . They have a number of lengths available:

https://chameleonantenna.com/shop-here/ols/products/cha-50-coax-with-integrated-rfi-choke-cha-50-cx-wth

My Key Mouse

Don also notes that CW Morse is now offering a USB-CW keyer/ device interface called the My Key Mouse. Check out the product description:

New for 2022! Morse Code Key to USB Adapter!

Did you know that there is an ever growing list of Software and Apps that allow you to practice and/or learn Morse Code using Computers, Laptops, Tablets, Android and other devices? Truly a great idea, but, if you’ve ever tried using a mouse to send Morse Code, I am sure you’ll agree that it is makeshift at best. But why?

Because It takes the right tools for the job!
To Send Morse Code it takes a Proper Built Key Or Paddle.

Now You can practice with a host of software and apps using your own device!

Click here to read more.

Many thanks to Jesus Alberto de Lorenzo who shares a link to a fascinating field activity based in the Canaries: VCAN — a Volcano program!

Click here for full details.

Thanks to everyone for the tips!

Antennas, POTA, QRP

The importance of quality cable and connectors

4 Comments

Note that this post was originally published on the SWLing Post, but I feel like quality cable is especially important for those of us who are into field activities like Parks On The Air (POTA) and Summits On The Air (SOTA) where our gear gets a lot of handling and outdoor time.

Two radio accessories I often forget to mention in my posts and reviews are cable and connectors. When a cable functions well, it’s taken for granted and easily overlooked.

You’ll hear me say that a radio is only as good as its antenna and while that’s true, the important link in the system is your antenna cable and connectors. If you have a fabulous antenna and a benchmark radio, but you connect the two with substandard cables, it will create unnecessary losses and even shorts if you’re not careful.

But let’s be honest: it’s easy to cheap out on cables.

When I first started using tabletop receivers and transceivers in my youth, I had a tight budget. When I would go to a local hamfest where I’d find excellent prices on cable assemblies from those accessory retailers who sell a little bit of everything.  You know…the tables with everything from $10 multimeters to $5 blinking lights–? I’d find their prices for cable assemblies too attractive and would grab them.

No more.

Back when I owned my original Yaesu FT-817, I used one of these cables on Field Day and blew my finals due to a small short ono a connector end (if memory serves, braiding was touching the conductor). From that point forward, I decided I’d invest in quality cables.

ABR Industries

At the Hamvention in 2010, I found ABR Industries’ table. The only thing they had on display were cable assemblies and a handful of cable accessories. I picked one cable up and inspected it–I could tell it was good quality. Although I know how to make my own cable assemblies (with PL-259s, at least) I appreciate professionally-built assemblies.

I spoke with the representative that day and learned about their company and how they go about making standard and custom cable assemblies in the USA for the consumer, commercial, and government markets.

Although the price was at least double what I would have paid at one of the discount retailers, I never looked back.

From that point forward, I’ve only purchased ABR cables typically at Hamvention, Universal Radio, or even directly from ABR’s website (when I ordered custom assemblies).

The quality of ABR cables is second to none. I have never had one fail at home or (especially) in the field.

For my QRP POTA activations, I started investing in ABR316 and ABR100 BNC to BNC assemblies. I’m especially fond of the ABR316 assemblies (above) because they’re so resistant to memory when I coil them.

You pay for what you get

I suppose this is on my mind because I’m about to do an assessment and make another ABR order so that my new field radio kits have their own dedicated cable assemblies with correct ends (so I’m also not forced to use BNC or PL adapters for matching).

I’m also replacing some of my 3 foot cable assemblies with SMA connectors to PL-259 for my bank of SDRs. This is a part of achieving one of my goals for 2021. I’ll know then that each receiver will have a quality link to my antenna splitter and antenna.

My point here is don’t skimp on your cable, adapters, or cable assemblies.

If you have the skill to build your own, buy quality components and take your time building them.

If you prefer purchasing pre-made cable assemblies, talk with your local ham radio retailer, or seek out cable assembly houses like ABR Industries. I’d avoid purchasing cheap cables you may find on eBay or Amazon.com, for example. That’s not to say that there aren’t quality discount assemblies out there, I just prefer buying from a company that takes pride in their work and stands behind the quality.

Click here to check out ABR Industries. 

ABR Industries isn’t a sponsor of the QRPer (although I’d love to add them!)–I’m just a long-time customer who is happy to plug their products. I can recommend them without reservation.

I’ve also bought numerous long cable runs, wire, DC cable, ladder line, paracord, and sealant from The Wireman. I also highly recommend them.

ABR isn’t the only quality cable assembly house–there are many others throughout the world. Who do you recommend? Please leave a comment and links to your picks!