572B Tubes

Discussion in 'Amateur Radio Amplifiers' started by AG4RT, Nov 3, 2015.

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  1. KA9JLM

    KA9JLM Ham Member QRZ Page

    What type of aircraft did you work with ?

    Most of the flight stuff I worked with, all wire was tested for out gassing. Many types you listed would never fly.

    What does cable have to do with 572b tubes ?
     
    Last edited: Dec 19, 2015
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    LMR cables from Times are excellent quality and professional installers use them a whole lot; but hams don't always use them the right way.

    I have seen amateurs use multiple layers of overlapping vinyl tape, pulled tightly, to bond them to tower legs. That's not a good idea. Using metal clamps or zip-ties pulled tightly is an even worse idea. And of course driving over it at Field Day is a super bad idea.

    Used properly, it's great stuff.
     
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The PTFE coax all would, and that's all we use in flight systems. The PE cables can outgas, but the LMR cables would outgas more.
     
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    That was the only type I have seen or used on air or spacecraft.

    It is harder to work with but tough to break after installed properly.
     
  5. KM1H

    KM1H Ham Member QRZ Page

    Who gives a rats a** what you did in flight test including deliberately or clumsily damaging cable?

    Im trying to relate it to ham and other 2 way and similar radio installations.where Ive seen more unusable RG-213 and 9913 and only rarely a poorly assembled LMR connector.
     
  6. VK3BL

    VK3BL Premium Subscriber QRZ Page

    I have to agree with Carl completely on this one. The "RG-213" we have in Australia is pure rubbish. The dielectric is incredibly hard, and prone to snapping in older cables; to the point I consider old RG-213 to be unusable. I'm much more cautious when using RG-213 over LMR-400 or equivalents.

    The people who talk about damaging LMR 400 with tightly wound electrical tape must be dreaming. The foam dielectric is significantly harder to compress than vinyl tape is to stretch.

    If you really think LMR-400 is easily damaged, cut open a length, extract the foam dielectric and experiment. I've got a section that I was bending into all kinds of shapes to amuse my children; despite the abuse, when straightened you can hardly tell it has been messed with.

    As far as I'm concerned, RG-213 is antiquated rubbish, and 99% of the available stock in my country at least is cheaply manufactured by no name companies. The same goes for RG-58.

    I'm sure I could source brand name versions, but why would I? Literally no one uses either of them professionally anymore. It isn't even significantly cheaper.

    My shack uses 100% LMR-195, LMR-240 or LMR-400, or reputable equivalent brands.

    As Carl also mentioned, there are some lovely connectors available for LMR that nearly anyone could terminate the cable with to a high standard.

    Time and time again I come across Hams who will just use whatever coax they have lying around, and then get fussy about tuning their linears up for the last 50 watts. I just don't understand that logic - they're happy to lose 2dB in their cable run, but need to ensure they get that last 1/8th of a dB out of their amplifier!

    Perhaps we need to start telling other Hams what feed line we use on air; maybe if feed line came with bragging rights people would start caring.
     
    Last edited: Dec 19, 2015
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    Nobody really.

    What does any cable have to do with 572B tubes ?

    You can use RG6 with those.
     
  8. VE7GPG

    VE7GPG XML Subscriber QRZ Page

     
  9. KC9VFO

    KC9VFO Ham Member QRZ Page

    I have accidentally kinked LMR 400 by not paying attention...it happens. I cut it at the kink and solder pl 259's and a barrel connector. Easy fix.
     
  10. N8VIL

    N8VIL Ham Member QRZ Page

    I have 100 feet of Davis BuryFlex to my HF antenna. About 35 feet of it is buried. I check it once a year with my MFJ antenna analyzer for any faults. It has been out there for about 6 years now and no problems. I also have 5o feet of it to my VHF antenna and have good performance. I believe it to be on par with the LMR-400 but less expensive. Appears to be a good quality cable to me. The braid is tinned and makes connector installation easier. It has to be good with a name like "Davis"
    Sean Davis
    N8VIL
     

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