QRP kit for 630m

Discussion in 'The Low Bands - 630/2200 Meters - VLF' started by K3RW, Jan 25, 2018.

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  1. K3RW

    K3RW Premium Subscriber QRZ Page

    Last week on Ebay I saw a ham selling what looked like a kit for 630m. He listed it for "600m" and it had "508KHz" written in pen on the board.


    This should link to the historic listing even though it has now been sold.


    I couldn't tell from the picture (I can only find the thumbnail now) if this was a kit for a different band, or if someone purpose-built it for 508. From what I could tell in the original photos the board had no trademarks or any info on it. CW only, if I had to guess. It seems to have a lot more than a QRP Frog Kit, which like this one also use the BNC connector out.

    I've often wondered why there is no board out there for the low bands. I can even source a 160m QRP kit. You'd think that someone by now would have the low band kit out there.

    Thought I'd share, and curious if there is a low band kit I've overlooked. I got my approval for the low bands but will probably mod the 7100 to do it short of a cheap(er) kit on the market. Juma is way out of budget for something I might try a few times.
  2. K8JD

    K8JD Ham Member QRZ Page

    If there is a 160M kit , u just need to triple the inductance of all the coils to get on 630M
  3. K3RW

    K3RW Premium Subscriber QRZ Page

    For a transceiver? If so, that's better than re-inventing the wheel. But I wouldn't mind chipping in a few dollars and crowd-funding a board if someone can design it. I've built the CW Pixie kit for 40m for less than $5. Any better designed board would just about have to be easier to solder.

    I see receivers that use a 475KHz crystal in them, but I've not yet found the 160m kit that I saw earlier this week.

    I'm not considering WSPR for the low bands, though there are kits for it. I'd like a more traditional CW QSO exchange.
    Last edited: Jan 25, 2018
  4. K3RW

    K3RW Premium Subscriber QRZ Page

    This isn't the one I saw last week, but here is another 160m transceiver kit--$47.


    Here's another--the Pixie II. Claims it operates 160-10m with the right crystals, though I now notice there's no info on the 160m part, and all the crystals are sold separately. Maybe it comes with the 160m one and I'd have to change to a different crystal for other bands (?).

    Pixie II:

    Receiver kits, I see lots of them. But 160m transceiver kits, seem to be far fewer under $50. Most I've seen are $100+
    Last edited: Jan 25, 2018
  5. N1BCG

    N1BCG Ham Member QRZ Page

    I'm looking into Class D FET transmitter designs. They work very well at low frequencies. Interestingly, there are a lot of inexpensive DDS VFO boards available online. For those who like crystal control, a simple "divide by 4" flip-flop circuit can turn a 160M xtal into a 630M xtal (1900kc/4=475kc).
    K3RW likes this.
  6. K3RW

    K3RW Premium Subscriber QRZ Page

    I've thought about that too. Sort of related--but how does one run a standard tube amp on 630m? Probably a silly idea, but wondered if running it on 160m and trying to run balanced line would actually work on the low bands, or if that's SWR no-no. Going to 2200m, I figured that's way too far, but who knows--maybe someone got it to work at a low level.
  7. N1BCG

    N1BCG Ham Member QRZ Page

    That works too, but L/C values are pretty big. I have a homebrew 100W tube rig that I'd like to put on the 630M band but the plate choke will have to be formidable. Fortunately, the band is so narrow (7kc) that fixed value caps can be used with only the need for small changes in C for fine tuning.

    W7UUU and K3RW like this.
  8. K3RW

    K3RW Premium Subscriber QRZ Page

    I read that I can disconnect the diode in my 7100 and it will transmit both low bands. I wonder about the implications of doing so, especially at any significant power level (burn up a final?). More inclined not to. But I'd have to get way out in the country to run a reasonable antenna, which would require me to modify my low-band license grant to that location. Running here in suburbia I doubt I'll make any QSOs other than a fellow ham across town, but I'd be happy to say I did. Trying to work ALL bands eventually.
    W7UUU likes this.
  9. N1BCG

    N1BCG Ham Member QRZ Page

    I dunno. The outputs are broadband, but only to a point. 630M is pretty low. Perhaps there's enough output to use it as an exciter.
  10. N1BCG

    N1BCG Ham Member QRZ Page

    Not necessarily. I'm a huge advocate of ops giving it a try and there are tons of low power NDBs (Non-Directional Beacons) in the 200-400kc range that can be heard a remarkable distance at night. Many use 25 Watts and a 50' vertical with capacity hat. That's pretty reasonable by amateur standards.

    Use this site to ID the stations you hear: http://www.dxinfocentre.com/ndb.htm

    There are two beacons in the 25W class that are about 30miles away that come in very well here day and night.

    Incidentally, a simple "L" match circuit will do wonders for reception. Use about 200mH in series between a 50' wire and your rig and a standard b'cast band 365pF cap from the ant end to ground. I wound magnet wire on a cardboard paper towel core (only needed 1" worth).
    Last edited: Jan 25, 2018
    K3RW likes this.

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