Coax Cable, RG-316 Question

Discussion in 'General Technical Questions and Answers' started by K2WH, Oct 14, 2021.

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  1. K2WH

    K2WH Premium Subscriber QRZ Page

    I just happened to find some coax cable laying around and found this real thin, small diameter RG-316 only about .1" in diameter, yes that is 1/10" in diameter !

    Looking up the specs on it I find that at 50 Mhz, it will handle about 850 watts and it is 50 ohms.

    Can someone confirm this for me, I looked over various loss charts and cable specs but I find it really hard to believe this tiny width cable could handle that much power and what would be the loss on a length of only 3 feet.

    Last edited: Oct 14, 2021
  2. WA0CBW

    WA0CBW Ham Member QRZ Page

    At 50 MHz the loss for 3-feet would be .16db.
  3. K2WH

    K2WH Premium Subscriber QRZ Page

  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    It can handle lots of power because it's Teflon cable.

    It can generate a lot of heat (which of course is loss) without deteriorating. PTFE is also a good HV insulator so it can handle high voltage well despite the thin dielectric. It's rated 2000Vrms (2828Vpk). It's FEP jacket material is immune to UV radiation.

    I still wouldn't use it as a "transmission line" when even RG8X has lower loss and is easier to work with. But I have a lot of 316/U and have use it inside chassis, even in amplifiers (short runs, intrachassis).
  5. W9GB

    W9GB Ham Member QRZ Page

    RG316/U Coaxial Cable: Small Diameter, Large Fire Resistance
    Frequently used in Balun designs, matching transformation (antennas), and
    Small jumpers within equipment, where FEP insulation desired.

    RG316/U designates a special form of coaxial cable.
    This coax cable has a 50 Ohm impedance (figure 1), making it ideal for data transmission.


    RG316/U has a small diameter (0.098" nominal), is extremely flexible due to its stranded center conductor, and has an Fluorinated Ethylene Propylene (FEP) outer jacket with an operating temperature of up to 200°C.

    Fluorinated Ethylene Propylene, also referred to as FEP, is a form of fluoropolymer insulation.
    FEP is very resistant to chemicals, has a broad temperature range and it exhibits excellent electrical properties. Due to these physical and electrical characteristics FEP is an excellent choice for use in chemical, medical, electronic and aerospace industries.

    A common use for FEP in military applications (MIL-DTL-17 specification) would be in coaxial cables such as M17/113-RG316, commonly referred to as RG316 coaxial cable. FEP, also called Teflon® FEP, is a variation of Teflon®, which was invented by DuPont™.
  6. K2WH

    K2WH Premium Subscriber QRZ Page

    My intent was to use in a balun or phasing harness, I was just surprised at the power handling capability and yes, I have used PTFE sheets to demonstrate to students, the hold off capability or the dielectric strength of a sheet of it using a hipot.

    Had a 12" x 12" 1/16" sheet of it in a GE lab, and put the ground lead of the hipot under the sheet and the hot lead on top of the sheet and even at 50kv, it only flashed around the edge, of the sheet, it did not puncture !
  7. KB1CKT

    KB1CKT Ham Member QRZ Page

    Wish I had "a lot" of RG-316, instead I wound up with a lot of RG-174 instead (hey, when it's free, you take it) (wish I'd quit accepting all those free colds however).
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I buy military surplus cables from Apex, and have for >30 years.

    I went in there probably ten years ago looking for about ten feet of RG-316/U for a small homebrew project. Turns out they had so many 100' spools of it they were stacked to the ceiling. I think I paid $10 for the 100 feet and am still slowly using it up.:) Apex is about 12 miles from me, a 20 minute drive over there.
    WA9SVD and W9GB like this.
  9. KB1CKT

    KB1CKT Ham Member QRZ Page

    Quick shows two routes--I can use the 45 hour one, or the 48 hour one. Those 3 extra hours might be well spent avoiding Chicago, last time I was there I think it was 3 hours--and I was only skirting around the city...

    We had an electronics surplus place locally, but they must have been omniscient as they closed shop a couple months before the pandemic hit. All my RG174 was from work, we used to make some cables for internal usage, and they cleaned shop one day. I think about half the building engaged in some dumpster diving that day...

    N3RYB likes this.
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I'd take the 45-hour route that goes through Las Vegas because you could stop in a casino and win a lot of money so you can drive home with more stuff.

    Everybody wins money in Vegas if you ask them.:)
    KB1CKT likes this.

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