Operating on the 630 Meter Band by John Langridge KB5NJD

About a year ago, US hams were given access to the 630 meter band. This slice of the spectrum is below the AM radio band at 472 kHz. You may have heard some bits and pieces about operating here over the past year, or two.

John Langridge KB5NJD recently visited the South Canadian Amateur Radio Society's (SCARS) monthly club meeting and set the record straight on 630 M. In this presentation, John has been running this band for over 5 years with an experimental license. Here he talks about how this band works and how you can get involved. He discusses receivers, transmitters, amplifiers, antenna tuning, and antennas for this band. He even describes the easy UTC notification system that's required to operate here.



More information about operating on the 630 meter band can be found on the SCARS 630 meter page, https://w5nor.org/630m/ that includes links to the content that John talks about in his presentation.

He's issued a challenge to Field Day crews to include a 630 transmitter at your next Field Day activity. SCARS is planning to set one up for the Winter Field Day activities as our first entry into this band. We've already notified the UTC for our normal Field Day site. Listen for W5NOR on 630 M on January 26th/27th. And make plans to join us there!

 

Really cool. I did watch the vid and will keep an eye on this. I'll probably never hit this band but still, really cool to dig into the technicals.

 

Like every band, it's a set of frequencies that will be approached experimentally, by the brave operators who go forth before the rest of us; establishing characteristics and propagation. Home-brew will expand into it, and QRP will reign supreme, until the big guys offer kits--then assembled transceivers that include this new frontier. I, for one, am grateful for the opportunity to check it out. I'm also grateful for the expansion--without sacrificing another band.

 

You might be surprised how little it takes to operate down there. I have a backyard vertical loop that operates at 475 kHz with about 2,000 pF of resonating capacitor across it. My back yard is 30 ft deep and 60 ft wide. The loop itself is 16 ft vert by 40 ft horz. The (six 4-ft mil tent pole segments) fiberglass poles holding up the loop are only 22 ft tall.

With 5 watts RF out of an Icom radio (yes, an Icom, I won't say which one ATTM) I worked (got spots) from a number of stations across the US using the WSPR mode using an exp lic granted about 3 and 3/4 yrs ago.

The WSPR map showing the WSPR spots is on my QRZ bio page. The loop is the same one I use for 160 meters but with a different matching network.

Oh, I live in "the city" too. That accounts for the little back yard.

 

Again, very interesting stuff. I did check out your QRZ; impressive stuff. I have the winter to think about the next leg of the hobby for me and certainly going to keep up on this band. I really like the idea of lower power and resident antennas - no tuners. They just fool your radio into thinking you measured twice and cut once.

Thanks again,

Jim

 

I'm assuming that you intended to say "resonant", not "resident", antennas.

 

Nope, I meant resident! They all are in my yard don't you know... Yup, it was late; red squiggle line, right click, send. I have a HEX antenna on the brain too but will stick with my 100 watts and wire philosophy.

 

Why not mention the radio? Many are looking for that sort of info.

IMO we need to get more technical people involved on this forum that can delve into various manuals and come up with ways to open up those locked out frequencies.

Ive been heard in Sweden and the West Coast with 5 W of CW starting with an old HP-606A signal generator and one of those /experimental licenses. A T top vertical hung off the side of a 180' tower and tied into the elevated radials for a phased pair of 1/4 wave 160M verticals sloping from that tower appears to do the job.

Im not going any further until I find out how to get some 630M RF out of the transverter ports of a TS-940 or TS-950SD.

Carl

 

Here's one difference that I can see between us Carl -

Me -- https://www.google.com/maps/place/7...ea1f48d7dd4482!8m2!3d33.0960711!4d-96.6508877

Carl - https://www.google.com/maps/place/1...79fedd8e67fda6!8m2!3d42.7491872!4d-71.3634407

See that dinky little lot I'm on amongst that "mass of humanity", very, very much like 99.9999% of the other hams living here in the Metroplex known as Dallas-Ft. Worth? Some would say I'm lucky to operate 160 like I do, let alone 475 kHz ...

 

What does any of that have to do with my radio question?

As far as location you have 25+ dB over me using WSPR vs my CW. I wasnt trying to belittle your results either, just thought you would get a kick out of my rather basic CW TX (into a 6AQ5 amp simply since I had all the parts vs going SS. The tower simply means I dont require an amp to radiate 5W and that ERP rule makes all us on 630 equal if we want to build an amp in order to radiate that.

 

I thought you wrote "A T top vertical hung off the side of a 180' tower and tied into the elevated radials for a phased pair of 1/4 wave 160M verticals sloping from that tower appears to do the job." which would seem to indicate to a fair-minded individual adequate space (or more) to erect same. Many of us have a lot less land to 'work' with. Frankly, I never expected to have the results I have had on 160 meters the last few years, working the Top Band Hams net on 1900 kHz where net control resides up in Pennsylvania. It was a 'fluke' that brought me to 630 meters, and after the 'fluke' I secured the exp lic with which I could do actual experimentation. You mentioned radio again. Well, I really don't want to be 'flooded' with a lot of follow-up questions that are sure to result from the disclosure ...

 

FYI - I have an old Icom IC-735 that is opened up for general coverage xmit and it seems to put out a few watts down there.

I only live on a city lot too but this week may see the 160m wires re-attached to the 30 ft high 80m vertical T top hat, and an attempt to wind up some added loading inductance to see how close to resonance on 630m it can get. Wonder if any "spots" can be generated

 

Good info, thanks.

Whatever works and the key is what leaves the antenna and not how much was required to do it. With WSPR, etc, that is a huge equalizer anyway and you should be heard well...just try to get some efficiency in the ground system.

It is hearing the other guy that will be a problem on small lots full of all sorts of RFI.

Good luck.

Carl

 

Would be much smarter to use the 735 transverter interface, with a transmitter for the band. The pi network on 735 doesn't do a good job on 474khz.