Selecting Coaxial Cable To Use With That New Radio

Hey, Which Coaxial Cable Should I Use?

Coaxial cables are the most popular form of transmission line for getting our signals to and from our antennas. There are many types of cable to choose from and it can be confusing to chose the best one. In this article, we’ll cover the most common choices of cable to get you started. We’ll focus on the most popular cables, with 50 ohm impedance to match the output impedance of our transceivers.

Here’s the really simple, short story:

Type Diameter Usage
RG-58 type 0.194 in Standard cable for mobile installations
RG-8X type 0.242 in Larger and lower loss than RG-58 but still convenient for shorter cable runs and jumpers,Up to 50 feet in length at 50 MHz or below (Rule of Thumb)

Up to 25 feet in length at 146 MHz (Rule of Thumb)

RG-8U type 0.405 in General purpose coaxial cable, best for long cable runs

 

coaxial cable

Comparison of three commonly used types of coaxial cable.

At one time, RG-58, RG-8X and RG-8U were military standards but now these terms are used rather loosely and refer primarily to the size of the cable. Accordingly, I added “type” to the term to indicate that it is not a precise standard.

All three of these cable types will handle 100W or more at frequencies below 500 MHz, which covers most ham transceivers.  If you are running more than 100W, you should check the power specification of the cable you are using. Times Microwave Systems has a very handy online calculator for coaxial cable specifications, which I used for the calculations in this article.

Signal Loss

All coaxial cables will attenuate the signal as it travels down the cable and the signal loss can be significant. For example, 3 dB of signal loss means that you lost half of the transmit power as it propagates down the line. This loss applies for both transmit and receive… we’ll get less power out to the antenna and we’ll have less signal showing up at the receiver.

The cable loss will be determined mostly by the size of the cable (bigger is better), the dielectric used in the cable (the insulator between the center conductor and the shield) and the frequency of operation. As an example, consider a 100 foot run of cable for use at 146 MHz, which is high enough in frequency and a long enough run such that we’ll see some significant losses. According to the Times Microwave calculator, 100 feet of RG-58 style cable produces a loss of 5.5 dB, which means that only 28% of the power gets through the cable. (The percent power delivered is shown as Cable Run Efficiency in the calculator.) This is not good, so we would rarely (never?) want to use RG-58 for that long of a cable run.

The Times Microwave Systems attenuation & Power Handling Calculator is a convenient online tool for comparing coaxial cable options.

The Times Microwave Systems attenuation & Power Handling Calculator is a convenient online tool for comparing coaxial cable options.

Changing the able to RG-8X drops the loss to 4.5 dB, which is only a minor improvement. (4.5 dB loss corresponds to 36% of the power makes it through.) However, using RG-8U type cable decreases the loss to 2.4 dB (58% of the power makes it through the cable), so clearly the larger cable size has an advantage. Now let’s change the dielectric. LMR-400 is a popular cable that has the same diameter as RG-8U but with a lower loss dielectric (Foam PE). The 146 MHz loss through 100 feet of this cable is 1.5 dB, or 0.9 dB better than ordinary RG-8U. A loss of 1.5 dB means that we still lose 30% of the power.

Now let’s see what happens when we change the frequency of operation. If we use our 100 foot run of LMR-400 on the 20m band (14 MHz), the loss is only 0.5 dB. This means that 90% of our signal power makes it through the cable. You can use the Times Microwave System calculator to try out different combinations of cable length, cable style and operating frequency.

Other Specifications

There are a few other cable specifications that you may be concerned about, depending on application. Cables with solid center conductors are less flexible than those with stranded center conductors. The dielectric material and the outer insulating jacket can also affect the flexibility of the cable. For portable operations, I make it a point to get cable that is rated “flexible” because it is easier to handle and deploy. Direct burial cable has a durable outer insulation that will withstand being buried in the ground. The type of outer shield used in a cable can vary widely, with some cables providing much more shielding and isolation than others.

This is a quick introduction to choosing the right cable for your amateur radio station. I hope it points you in the right direction. Its always a good idea to buy quality cable from a reputable supplier and to read the specifications for that exact cable type.

73, Bob K0NR

 

ARRL Membership/Renewals

Arrl_logoWelcome to the only national organization representing Amateur Radio in the US. As an ARRL member you support the ranks of thousands of other ham radio enthusiasts shaping the Amateur Radio service today. If you consider yourself an active ham… you need ARRL now. If you are not presently an active ham… let ARRL help you.

As a member of the ARRL, here are some of the benefits you will enjoy:

  • QST Magazine – your monthly membership journal
  • Online Services –
    • QST online monthly digital edition
    • QST Archive and Periodical Search
    • Product Review Archive
    • Email forwarding
    • E-Newsletters – delivered to your inbox
  • A voice in the affairs of ARRL and ham radio through locally appointed volunteers
  • Publication Specials and on-line course discounts
  • Emergency Communication Services
  • Technical and Regulatory Information Services
  • Operating Awards
  • Ham Radio Equipment Insurance Plan Available
  • Outgoing Foreign QSL Service
  • Plus much more!

Take the next step in being an active participant in the future of ham radio.  Join or Renew your Membership in the ARRL today through the Gulf Coast Amateur Radio Club (an ARRL Affiliated Club)!

Club Commission Program

Commission Terms

ARRL Affiliated Clubs receive a commission for every new ARRL membership and renewal they submit to ARRL Headquarters.

  • Clubs retain a portion of the dues for each regular membership submitted to ARRL Headquarters:
    • Clubs retain $15 for each new membership OR lapsed membership (of two years or more). A NEW MEMBER is defined as any individual who has never been a member of ARRL or any individual who has not retained a membership for two or more calendar years prior to the application submission.
    • Clubs retain $2 for each renewal. A RENEWING MEMBER can renew at anytime, even before their current membership term expires.
  • Family, Blind or 21-and-under discounted memberships are not applicable for any discount.
  • May not be combined with any other promotion or special offer.

Gulf Coast Amateur Radio Club Logo

<<< Help Us Help The ARRL >>>

(Click Below For ARRL Membership Application)

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Yes! check your membership card’s expiration date today.  The club gets money from the ARRL for all new memberships and renewals.  Contact Mike Christopher, W2IW, President GCARC

FCC Closing Some Field Offices

The Federal Communication Commission is confirming to Radio World that it
will begin closing field offices in January 2017. Offices in Anchorage,
Alaska, Buffalo, N.Y., Detroit, Houston, Kansas City, Mo., Norfolk, Va.,
Philadelphia, San Diego, San Juan, Puerto Rico, Seattle, and Tampa, Fla.,
will be closed as part of the agency’s modernization plan.

The FCC announced in July 2015 it was closing the offices and trimming up
to 44 positions to better reflect technological advances and in the face of
budget reductions. The modernization plan creates rapid response teams to
handle special enforcement issues. The FCC says the so-called Tiger Teams,
based out of Columbia, Md., and Denver, will be dispatched within 24 hours
of an interference crisis.

The restructuring plan has the National Association of Broadcasters and
the Society of Broadcast Engineers worried that the cuts in the field will
limit the FCC’s ability to mitigate interference complaints and leave
potential holes in the enforcement fence.

Before the plan could be implemented the FCC had to reach an agreement
over the projected job losses with the union representing FCC Enforcement
Bureau field employees. The National Treasury Employees Union has been a
vocal critic of the overhaul plan, openly questioning the commission’s
ability to safeguard radio spectrum going forward. An FCC spokesperson
confirmed on Thursday that the displaced FCC agents will have the
opportunity to apply for vacancies in the remaining field offices if a
vacancy exists.

FCC field offices will remain open in Atlanta, Boston, Chicago, Columbia,
Md., Dallas, Denver, Honolulu, Los Angeles, Miami, New Orleans, New York,
Portland, Ore., and San Francisco.

Weather Related Nets & Tools

Docket RM-11708 – Amendment of Part 97 of the Commissions Amateur Radio Service Rules.

Update!!!

Regarding the filling of comments opposing RM-11708

This is a response to comments sent from one of our members.  Make sure you send your comments to both email address.

The FCC is about to make this officially law, but is taking last ditch comments from now (up until October 5th or so) and then during a one month “Reply to Comments” phase. this is our LAST CHANCE to really get the base of CW/RTTY users to write in to ARRL and FCC officials to modify this law…. NPRM RM 11708 cannot be repelled at this point, only modified, unless a miracle occurs and ARRL recinds it – not likely unless tens of thousands of us write to ARRL officials while also filing comments.

Here is what RM 11708 will enable, if it is passed into law as the FCC is proposing in its NPRM 11708 published on July 28, 2016. Note the FCC ignored ARRL’s request for a 2.8 kHz bandwidth to replace the 300 baud limit, and instead is proposing an **unlimited** bandwidth limit with no baud rate limit. Unfortunately, neither the ARRL or FCC have recognized the resulting interference that will occur to the narrowband CW and RTTY users, and have never once considered a 200 Hz bandwidth emission limit on the lower 50 kHz and 500 Hz emission bandwidth limit on the lower 100 kHz of every HF band (That is what is needed for protection, and we must write in by the tens of thousands!!! To ARRL and to FCC! See footnote 37in their July NPRM, very short shrift given to this argument!). Here is what will happen if CW/RTTY apathy continues:

1. SSB and other voice operations will be freely allowed in all the CW/Data/RTTY segments of HF with unlimited bandwidth, as long as the signals are digitized into data first. This NPRM opens up digitized voice to the CW/RTTY lower end HF bands — digitized voice using 12.5khz c4fm stations will be allowed, since the FCC has not proposed a bandwidth limitation. And this is not a conspiracy theory, its real.

2. If the rule passes without any bandwidth limit, or with the ARRL’s suggested 2.8 kHz bandwidth limit on the low end, Pactor 4 will be permitted and conversations will be encrypted as part of the protocol. And if there were to be a way to listen in, it’s going to require a the purchase of a Pactor 4 modem which is not cheap. Meaning you have no ability to identify the call sign of a station short of engaging in a Pactor 4 based conversation. No way for OO’s to find offending station since no CW id is needed.

3. A lot of the Automatic Data stations (the auto repeaters that are already causing great QRM) are tied in with the watercraft and boating crowd. Which means the stations would ring the coastline using new data services in the CW/Data part of the band to log into Facebook, check weather, and make dinner reservations. So unless you are beaming north, you are going to be pointing toward one of those stations.

4. At about 2.4 Khz per station for Pactor 4, and with MANY more stations active (the P4 speeds make email via HF a lot faster and less painful, which will drive more users after this NPRM is legalized), it won’t take much to swamp all the traditional RTTY segment. That pushes the RTTY guys down into the top of the CW segment. And not to even mention digitized voice signals that will be allowed there, too!

No matter how you slice it, even with voluntary band plans, this means trouble for the RTTY operators right up front, and more congestion for the CW bands as a result. Of course, the SSB guys successfully defeated essentially the same proposal 10 years ago (ARRL TRIED TO PASS RM 11306 in 2005, but rescinded it in 2007 because the SSB operators made enough noise to get the ARRL to pull it from the FCC consideration—Check out RM 11306 and — CW and RTTY apathy has failed to make enough noise, and now this is about to become law). It has gone too far, and CW/RTTY people have not been heard, and this is about to remove the enjoyment of our bands forever! Please get active. This is real. Please don’t take this lightly and do nothing, please get your CW/RTTY friends engaged. Read the NPRM! See Footnote 37. See what the FCC is about to sign into law. You only have 2 months to move the ARRL and the FCC to modify this rule.

Lets give Pactor 4 and Winlink its due at 100 kHz and above from the low end of HF, but lets also preserve the lowest 50 kHz for CW and lowest 100 kHz for RTTY by urgently requesting bandwidth limits that preserve CW and RTTY.

Tell your ARRL official and write in to the FCC about the need to have narrow bandwidth protection in the low end of HF if they remove the 300 baud rate — we need tens of thousands of thoughtful responses! I am copying Brennen Price, ARRL’s CTO and PVRC member, here. And I hope you and others will similarly write him and all ARRL officials while you submit your short, focused comment to the FCC on RM 11708 and WT 16239 to seek interference protection on the low part of HF, as well.

What we are asking you to do is to contact the FCC and express your opinion of this proposed rule. We have until October 11, 2016 to submit comments and reply comments by November 10, 2016.


Amateur Radio Code

hamradioopThe Radio Amateur is …

CONSIDERATE… never knowingly operates in such a way as to lessen the pleasure of others.

LOYAL… offers loyalty, encouragement, and support to other amateurs, local clubs, and the American Radio Relay League, through which Amateur Radio in the United States is represented nationally and internationally.

PROGRESSIVE… with knowledge abreast of science, a well-built and efficient station and operation above reproach.

FRIENDLY… slow and patient operating when requested; friendly advice and counsel to the beginner; kindly assistance, cooperation and consideration for the interest of others. These are the hallmarks of the amateur service.

BALANCED… radio is an avocation, never interfering with duties owed to family, job, school or community.

PATRIOTIC… station and skill always ready for service to country and community.

— The original Amateur’s Code was written by Paul M. Segal, W9EEA, in 1928.

Amateur Radio Parity Act

New – Consensus on Bill Language – June 2016

ARRL and the Community Associations Institute (CAI) — the national association of homeowners associations (HOAs) — have reached consensus on provisions of the Amateur Radio Parity Act, H.R. 1301. ARRL and CAI have worked intensively since February to reach agreement on substitute language for the bill in an effort to move it through the US House Energy and Commerce Committee. Read the complete story here.

The full text of the substitute bill is here.

<<< Important Update From ARRL >>>

Subject:  ARRL Urgently Requests the help of Members in Florida To Support of the Amateur Radio Parity Act

To All Our ARRL Members in Florida –

I am writing to you today because we are at a critical juncture in our efforts to obtain passage of The Amateur Radio Parity Act in the U.S. Senate (S.1685).

Senator Bill Nelson (D-FL), is not yet supporting the legislation despite the recent agreement between ARRL and the Community Associations Institute (CAI). This agreement is supported by all parties to the issue and leaves no visible opposition to the bill.  However, Senator Nelson’s support is critical to the success of our efforts.

You are one of well over 40,000 licensed Amateur Radio Operators living in Florida. Many of you already live in deed-restricted communities, and that number grows daily.

If you would like to have the opportunity to have an effective outdoor antenna but are not currently allowed to do so, or you already have outdoor antennas and want to support your fellow hams, then we need you to reach out to Senator Nelson TODAY! Right away.

Please go to this linked website and follow the prompts. The link will provide you with a letter that you can send to Senator Nelson.

https://arrl.rallycongress.net/ctas/contact-senator-nelson-regarding-amateur-radio-parity-act

Thank you.

73,
Rick
– – – – – – – – – – – – – – –
Rick Roderick, K5UR
President
ARRL – The national association for Amateur Radio™

Skywarn Spotter

NWS Tampa Bay SKYWARN® Program

skywarn logoThe impacts of hazardous weather are experienced by many Americans each year. To obtain critical weather information, NOAA’s National Weather Service (NWS), part of the U.S. Department of Commerce, established SKYWARN® with partner organizations. SKYWARN® is a volunteer program with nearly 290,000 trained severe weather spotters. These volunteers help keep their local communities safe by providing timely and accurate reports of severe weather to the National Weather Service.

Please see http://weather.gov/tampa/?n=wx4tor for information on amateur radio networks and frequencies

 

Spotter Network LogoMetEd Logo

 

Take One or Both of these FREE Online SKYWARN Spotter Trainings

Three Training Options to become a Spotter for NWS Tampa Bay.  Spotters should renew every 3 years.

  1. Attend an in-person training (see schedule below)
    • These are few and far between and run from October through April
    • We do our best to do a training in each county every year
  2. Join the Spotter Network at http://SpotterNetwork.org
    • Create an account
    • Take their SKYWARN Spotter online training and pass quiz to become a member
    • Click on “Member Networks” in left hand menu, then join “Tampa Bay, FL (NWS/TBW)”
    • If you would like a NWS Tampa Bay Spotter ID, send us an Email after you’ve joined our member network and we will mail it out in 1 to 3 weeks.
  3. Take the MetEd SKYWARN Spotter online trainings above
    • Email your county location and both certificates to both daniel.noah@noaa.gov and jennifer.hubbard@noaa.gov
    • Check box to notify local WFO
    • It may take 1 to 3 weeks to receive your Spotter ID, but we will acknowledge your Email when we receive it

Tuesday Morning Coffee Break

When: Every Tuesday (Starts April 19th, 2016) at 10 AM

Where: McDonald’s (11542 US Hwy 19 N, Port Richey, FL 34668)

Every Tuesday morning at 10 AM (excluding Holidays) the Gulf Coast Amateur Radio Club will hold its informal coffee break at McDonald’s on US Hwy 19 N across from the Flea Market in Port Richey, FL. Hope to see you there.

73,

Michael Christopher, W2IW

President GCARC

<<< Come Join Us For Your Tuesday Morning Coffee Break >>>