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Adaptation for 2200m Rx/Tx

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by WQ2H, Oct 26, 2018.

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  1. WQ2H

    WQ2H QRZ Lifetime Member #214 Life Member Platinum Subscriber QRZ Page

    I'd like to see if I could utilize my 160m full wave loop (horizontal ~30' high) for Rx/Tx on 2200m.

    My first thought was to un-hook one end, redirect it away from the feed point, and then load the feed point with a variometer (~1500uH + or - a few hundred uH) . I would probably also build one of M0BMU's tuners to help get the load right. I'm not an EE, but it does look fairly straight forward.

    Any other (simplier) ideas or suggestions?

    73
    Jim, WQ2H
     
  2. K8JD

    K8JD Ham Member QRZ Page

    But it's so tiny ! :eek:
    2200 M band wavelength is about 1.1 Miles !
     
    KA2RRK likes this.
  3. WQ2H

    WQ2H QRZ Lifetime Member #214 Life Member Platinum Subscriber QRZ Page

    Obviously. :rolleyes:

    The thought was to attempt a loaded radiator - similar to a shortened dipole, vertical., or endfed. You'll never get anywhere near full efficiency, but if tuned properly with an integrated variometer - you might end up with something that has a reasonable SWR.

    Open to suggestions, but I think a 1500uH load might do it ??
     
  4. AA7QQ

    AA7QQ Ham Member QRZ Page

    What about using a tube audio amplifier, with impedance transformation up to 50 ohms? Of course, there will be changes, but you would then be able to operate into such a low impedance that you would see (I think) with better efficiency.
    12.5:1 transformer from 50 ohm transmitter & then add a tank circuit to make it work.
    Am I off base?

    Ed
     
  5. K6CLS

    K6CLS Ham Member QRZ Page

    Get the RSGB book "LF Today", which covers both 2200m and 630m.

    There's no reason to reinvent the wheel. This has been understood for 100 years.

    My pixel loop does a great job for just listening on these bands.

    For a variety of reasons vertical is better on these bands. Yes it needs a variometer. On 2200m, use a 50 gallon plastic trash can, and wrap around that. Use Litz wire for the inside coil. The audio amp is a good suggestion, also consider building a class E amp, much smaller and cooler and more efficient.

    I understand the biggest thing on 2200m is to manage the arcing and Coronas, so the mast and nearby trees and your house doesn't catch fire!!

    Very precise frequency control of the LFO is crucial. Like, to the milliHertz and better. Google for "time nuts" to understand the challenges. Just like on microwave frequencies.

    Enjoy!!
     
    KA2RRK likes this.
  6. WA7F

    WA7F Premium Subscriber QRZ Page

    Wow, I never would have thought that arcing and Coronas would be a problem at 1W EIRP. The antennas are probably a bit lossy though. How much power does a guy need at the amp to get one watt out of a typical 2200m antenna?

    I could fit a full wave loop for 600m easily enough but, 2200m is another story.
     
  7. WQ2H

    WQ2H QRZ Lifetime Member #214 Life Member Platinum Subscriber QRZ Page

    Thanks for the advise, and I do understand there is a huge difference between Rx and Tx this low.

    I already have a 50W transverter transceiver for 2200m, so I've got somewhat of a leg up. There is also tons of LF antenna projects on the internet. Maybe it's not possible, but I was trying to adapt an existing wire.

    Never had an HF/LF vertical before, but this may be a good opportunity to build one.

    73
    Jim, WQ2H
     
  8. K6CLS

    K6CLS Ham Member QRZ Page

    Wow!! Can you post some details / pictures too?
     
  9. WQ2H

    WQ2H QRZ Lifetime Member #214 Life Member Platinum Subscriber QRZ Page

    Yes I will certainly do so. I've also ordered that book - thanks for the suggestion. (ARRL was out, so had to go Amazon) Looking forward to reading it.
    Keep in touch !
    73
    Jim, WQ2H
     
  10. WQ2H

    WQ2H QRZ Lifetime Member #214 Life Member Platinum Subscriber QRZ Page

    Last edited: Nov 18, 2018

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