630 Meters

Authorization Letter

October 23, 2017

 

Dear Mark Edwards (W0QL),

We apologize for the delay, this notice is being provided to approve your proposed amateur radio station in the 472.0 – 479.0 band(s) at the following coordinates:  39⁰ N 35’ 40”, 104⁰ W 18’ 55.600000000000001”.   UTC has determined that your proposed amateur radio station would not operate within a horizontal distance of one kilometer from a transmission line that conducts a power line carrier (PLC) signal in the 472.0 – 479.0 bands. 

Please direct any questions to the undersigned.

Mike Etzel

Mike.Etzel@utc.org

202-833-6839

End of Letter

 

630 meters (and it’s partner, 2200 meters) were given official permission by the F.C.C. to operate as of October 16, 2017.  I hope to operate 630 meters with JT9 and WSPR (and maybe even FT8).  A process to register a station has been implemented to notify power companies of amateur operation.  Of course, W0QL filed an application immediately.  The FCC notice started off a long list of action items to get done before we can get on the air.  We made some quick decisions.

  • Antenna:  Possibility one – The existing 6 meter antenna is mounted on a 39 foot aluminum mast.  That mast could be pressed into service right where it is as the vertical portion of an inverted L antenna.  The plan is to lay radials around the base of the vertical after cutting the weeds to make room.  A thin wire will run from the top of the mast over to the top of the 20 meter tower about 200 feet away.  Plans came from this article: http://www.wd8das.net/630mPractical.pdf   Possibility 2 – There is an unused ground screen in place we could erect a vertical over.  It was used unsuccessfully for the 6BTV vertical. Possibility 3 – Use existing big vertical with a relay to switch from current operation to 630 meters.
  • A variometer will be built to resonate and match.  The variometer is under construction using scrap pvc pipe.  Plans for the variometer came from http://www.g0mrf.com/variometer.htm.

IMG_2081

  • img_2082.jpg
  • Rig:  Possibility 1 – Luckily the existing Kenwood TS-480 receives down to the operating frequency for 630 meters, 474 kHz.  Antenna port 2 can be used leaving antenna port 1 in tact for the existing station.  A 630 meter downconverter has been built that provides 20 watts output from 1 watt input.  The TS-480 minimum power output is 5 watts so we will need an attenuator in the line when transmitting.  With a relay driven by the PTT line the attenuator can be bypassed for receiving.  Possibilit 2 -Also under consideration is the K3 because it can put out 1 watt and wouldn’t need an attenuator.  Possibility 3 – The Yeasu FT-817 puts out a 1 watt or less signal in the 80 meter band that could drive the downconverter.  This arrangement has been bench tested and the output is 15 watts at 474.2kHz.  Perfect.  The FT-817 already has the necessary hardware interface and software running on a Intel Compute Stick from an earlier wspr project.  It can be diverted to 630m use.

In all cases possibility 3 seems most viable.

U.S. Amateurs will be allowed to run a maximum of 5 watts EIRP, which is about 1.6 watts ERP.  The short antenna will be inefficient relative to a full size dipole (991 feet long) and should keep us legal.  Radiation resistance is estimated to be .4 ohms and ground loss 6 ohms.  That gives us efficiency of 6.25 per cent.  Our 20 watt downconverter would radiate 1.375 watts erp and be compliant with the regulations.

The magnet wire arrived in the mail today.  This will become the winding for the variometer —  325 feet of 16 awg.

img_0016

The coils are wound:

IMG_2167IMG_2169

UNfortunately, the coil only measures 800 micro henries and we need 1900 according to the online calculator.  The eBay listing said the diameter of the wire is 0.0520″.  Two hundred turns would be about 10.4″. I might try it temporarily on the big vertical in Strasburg.

 

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