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HamRadioNow: REALLY understand SWR, then celebrate Episode 200 (whohoo)

Discussion in 'Amateur Radio News' started by K4AAQ, Apr 24, 2015.

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  1. K4AAQ

    K4AAQ Ham Member QRZ Page

    [​IMG]
    [COLOR=#0000FF]HAM[/COLOR][COLOR=#FF0000]RADIO[/COLOR][COLOR=#0000FF]NOW[/COLOR][COLOR=#000000].tv[/COLOR]
    Episodes 198. 199 and 200!
    A crass little commercial,
    Standing Up for Standing Waves,
    and in 200,
    BS#3 (Media Edition)

    We've been busy here at HamRadioNow, so I waited to spam QRZ.com until the waves stopped rolling in.

    Episode 198 is the crass commercial. It's not for us, it's for the company that makes our "logo-wear." We're so non-commercial we won't even mention their name (but they also make the QRZ.com logo-wear). The episode features the long-delayed interview with the ham at the 2014 Hamvention who was the first to wear a HamRadioNow t-shirt. His 15 minutes of fame only took 4 minutes! HamShirts.com (oops) is also selling some cool plaques with your FCCish license on them, and they look really cool. Or you could get it printed on a coffee mug.

    Episode 199 is Standing Up for Standing Waves. It's a tabletop demonstration that lets you see SWR on a transmission line. If you want a quick idea, go here and scroll down to the preview. The program was presented by Bill Hays AE4QL way back in 2005, and the DVD was the first one I produced under the ARVN logo. But the technology doesn't change much, and the topic is evergreen, so we finally decided to put it on the web (but really, we need to shoot it again in high-def with multiple cameras).

    And finally, Episode 200 (woohoo)! is the third in the BS (Bull Session) series, though this one's just me, so I must be just dishing out the Bull in this Session. Newsline's Bill Pasternack WA6ITF was going to join me again, but he's had a medium-size setback after getting home from the hospital, and wasn't feeling up to sitting in front of his computer for a couple of hours. I'd prepped to review some of the ham and general media about ham radio, and as Bill would be the first to say "The show must go on!," so I ran through it on my own (I missed you, Bill!). I think I did OK, but Bill would make it more fun (and it would be a 3-hour show). I'll get Bill on in the near future – there's always something to talk about.

    Here in the box is #200 (woohoo). Bookmark the SWR show and watch it when you can (it's about 90 minutes, I think). And check out the goodies show (only 11 minutes), because Father's Day (and Mother's Day) is coming up, or maybe somebody's birthday, and even that holiday in December that I won't mention this early, but for the ham who has everything... I'm just sayin' ...


    [video=youtube;I47sToSZp7I]https://www.youtube.com/watch?v=I47sToSZp7I[/video]​



    Watch all our programs on our web page:
    HAMRADIONOW
    .tv

    HamRadioNow is supported by viewer contributions
    If you enjoy the programs, visit www.HamRadioNow.tv and "click the pig"


    [​IMG]

    THANK YOU to all our contributors!
     
  2. W1YW

    W1YW Ham Member QRZ Page

    If hams could easily measure gain, no one would have this obsessive interest in SWR.

    And we didn't--back 30 years ago. Its only with the finicky matching of solid state xcvrs and only marginally over engineered amps that SWR became an issue of the present magnitude. Before, a 2 to 3: 1 SWR was an annoyance, not a quest to vanquish.

    You need almost a 6:1 SWR to see a 3 dB loss in power to the antenna from mismatch...in most cases the insertion loss of long length of old coax is at least that. But we dont go digging up old coax every two years.

    My theory is that getting a 1:1 match makes us feel good about ourselves..

    73
    Chip W1YW
     
  3. W5NIO

    W5NIO Ham Member QRZ Page

    Gary, I'm 12 and have a license and I would like to say how good and interesting your videos are.
    73!
    Jack Paylor, KG5FBC
     
  4. K2NCC

    K2NCC Ham Member QRZ Page

    I try to eek out every dB I can. Just a couple can be the difference between copy and no copy with some modes. Finally got the entire station down to zero adapters for instance. Shortened and upgraded the coax and other little "fixes" here and there. To me, if you have a too-high SWR, then your antenna is broken! :) I figure a antenna "tuner" is more like a last-resort option.
     
  5. AA9G

    AA9G Ham Member QRZ Page

    Gary, congratulations on your 200th show. :cool:
     
  6. N9XR

    N9XR Ham Member QRZ Page

    I think you use this link... http://www.csgnetwork.com/vswrlosscalc.html

    You will get ~3dB loss with an SWR of 6:1.

    I use this link and get much less loss with high SWR. http://www.arrg.us/pages/Loss-Calc.htm

    I can get 3dB of loss with an SWR of 22:1 at 10MHz and 100 ft of Belden 9913.

    I have a few bridges for sale as well. Cheap.
     
  7. W1YW

    W1YW Ham Member QRZ Page

    5.8 :1 SWR gives a mismatch loss of 3db. I did not use any link.

    Buried coax deteriorates with time and for many types 3 db insertion loss after a couple of years of dew and ice is typical. Unless you can do S12 on old coax , to check it against a short reference length,I recommend chucking it out.

    I have no idea what your con artist ref is supposed to mean, and wont try.

    Chip W1YW
     
  8. W1YW

    W1YW Ham Member QRZ Page

    If you do the actual calcs for SNR and mismatch loss for SWR under 2:1, you will see the actual loss is trivial. Unless everyone starts using an IC 7700, with the very best xcvr RX of all, the marginal copy threshhold is dominated by other factors than, say, going from 1.2:1 to (ugh) 1:1.

    Most rigs cut back output power for moderate swr so the transistors dont fry....

    Your internal ATU probably contributes more insertion loss than you make up from midmatch when the SWR is already, say, 1.5;1 diwn to 1:1. But thePA transistors are happy...

    I wish we talked about takeoff angle as much as we obsess on SWR :)

    73
    Chip W1YW
     
  9. KA2CZU

    KA2CZU XML Subscriber QRZ Page

    Not sure if this diversion helps, but in my opinion, your 200th "show" still IS your 200th "show" no matter how many "videos" you have embedded within any particular "show".

    An episode, by definition, is "an event or a group of events occurring as part of a larger sequence; an incident or period considered in isolation."

    So, it can be construed as a collection of "videos".

    Basically, ignore youtube's count and just celebrate (albeit low-key due to your friend's health situation).

    Congrats!
     
  10. KA2CZU

    KA2CZU XML Subscriber QRZ Page

    Young ham of the year (I have no idea what criteria needs to be met);

    Hope, 8 years old
    KM4IPF [​IMG] USA
    Hope M Lea
    929 Still Harbor Circle
    Chesapeake, VA 23320
    USA

    She's been active on SO-50 this spring and has great operating technique!
     

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