Both 65 Foot Masts Go Down In Storm

Both the north and the south 65′ aluminum masts went down in the snow storm Sunday.  They both failed in almost the same place about two-thirds up.  What a mess.  First the south mast, then the north.

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Plans for what to do next are not worked out.  KC0RF has made several suggestions:  slopers from the tower, a 43 foot vertical, a HyGain Hytower, and replacing the masts with 65′ Telrex tubular crankup masts.   We’ll use EZNEC to help us evaluate these suggestions and maybe come up with some of our own.  One of my ideas would be to replace the .058 tubing with .12 inch.

A Plan Emerges Finally

Consider this: they both failed at about the two thirds point and the highest level of guys had been moved up to the top of the mast against the DX Engineering instructions.  The top would not have been supported per the instructions and surely would have failed with  antenna ropes pulling horizontally.  That’s why the guys were moved up.  Unfortunately it left too large a section unguyed.  Armed with this analysis the next attempt will be to guy exactly per the instructions and then add a fifth set of guy ropes to the very top.  Replacements for the bent sections will be ordered.  Only one mast will be done this way as a test.

January 27, we salvaged the north mast and re-purposed the tubing that wasn’t damaged.  Taking one of John’s suggestions we made it into a 43 foot vertical.  The North mast now:

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So far performance has been excellent, working quite a bit of dx.  Next upgrade will have to be a higher power tuner (MFJ 998RT) so we can run a few more watts to make up for the inefficiencies.  Frankly, I’m surprised at how well this antenna performs.

South mast:  A week later we cut off the bent top sections.    South mast now:

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A road grader in the background is building an access road in the easement next to our property.  Progress I’d be happy to forego.

Unfortunately with John’s help we tried to raise the repaired 65 foot south mast complete with 5 guy levels and it collapsed when it was about 90 per cent up.  This makes the fourth time one of these aluminum masts has collapsed.  You know what they say.  Four strikes and you’re out.   No more 65′ masts at W0QL.  Next we’ll look for some suitable solutions closer to the ground.

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Taller Vertical Antenna – “North Mast”

The main 56 foot low band vertical has been extended to 65 feet.  It took a full day to do it because of it’s unwieldiness and a constant 16 mph wind.  Thanks to John, KC0RF for giving up a full day to help.  Here’s what it looks like with the additional height and a small top hat to resonate to 3.573 kHz  (the FT-8 freq). This is both a vertical antenna and the north mast which is planned to hold up two dipoles.  The south mast (below) is planned to have the other end of one of the dipoles attached.

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The 30″ top hat is very hard to see when it’s 65 feet up in air.  A better picture is coming soon.

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The antenna is designed as a full quarter wave on 80 meters.  Using a MFJ 259B  the impedance at 3.573 kHz reads 55 -j0.  SWR is 1.1.   Apparently we hit the resonance perfectly but the ground screen needs to be improved to bring the resistance down to 36 ohms.  The match was planned to be a direct match for a 50 ohm coax.  As an experiment we left the existing tuner installed and tried it on other bands.  It works on all bands, 160 through 10 meters even though the take off angles may be awful and the tuner losses may be especially high at the even harmonic frequencies.  We’ll leave the tuner in for a a few weeks to see where it works and where it doesn’t.

 

Amplifier.

Once in a while a little extra help is needed to obtain a contact with a DX station.  That extra help can come in the form of a few more watts.  When a difficult DX contact is completed we call that being deserving, as in, “We are among the deserving” (Where Do We Go Next, Martti Laine, OH2BH).  Here is a photo of the new amp and my silly grin shows a combination of emotions.  Sheepish for adding power to a weak signal mode but thrilled at the same time.

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(Actually the emotion is more, “Can I get this damn cell phone to take a selfie”.)

Design contraints of a remote base off grid quickly narrow down the choices of linear amplifiers.  The SGC  SG-500 was the obvious choice because it changes bands automatically using rf sensing, runs the finals at 12 volts, and has a remote on/off switch ability.  Luck was with us when we found this pristine SG-500 at a good price online at QRZ Swapmeet.

The amp can draw up to 90 amps.  We rearranged the battery banks to dedicate one bank to the amp.  Everything else is on the other bank. Testing showed up no problems except a tired SO239 coax connector.  We escaped replacing that by using a PL259 with a slightly longer center pin so it would push against the solder cup at the back.  Deferred maintainance.  With 10 watts input the output is 150 watts with no complaints from anything else in the station.  On to the first on-air test.

First QSO

Wow, amazing, superlatives are not enough.  Noticing a big pileup for a station with the call 3D0AY (Swaziland) I found a clear frequency and clicked the transmit button.  Seven others were calling at the same time.  With only four calls, on the 4th transmission he came back to me!  Here is the proof.

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As soon as Swaziland anwered my call another station jumped on our frequency.   I found another clear spot and tried to complete the qso with Swaziland.   He came back again and we completed the contact.  Another station immediately jumped on the new frequency.  A difficult qso but my station joined the “deserving”, thanks to the new amp.  I’m hooked.  I’ll be using this whenever a pileup is tough.

Unfortunately there has been no second qso using the amp.  It seems to be malfunctioning.  It began immediately switching off and the high vswr warning light came on.  Changing to manual PTT got rid of the vswr alarm but no rf comes out of the amp.  It draws a large amount of current but where are those amps going?  It will probably have to go back to SGC for a look.  For the time being we are not using an amplifier.

Update:  I tried the amp using a different radio and it works perfectly.

 

 

South Mast Erected

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Sixty-five foot mast from DXEngineering completed today and looks amazingly vertical.  Getting it up was like raising a wet noodle.  Here’s what it looks like on the ground.

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The secret is to never let the attachment point get below the bow point.  Lift the upper sections first and keep them under upward pressure so a downward facing bow never forms.

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When it’s all over it looks like the top picture. This will be the south support for a 40 meter dipole and possible for a 630 meter antenna.

Revitalizing The Antennas

Adding a tuner to the 20 meter yagi didn’t work out so well for 15 meters and 17 meters.  Next trial is erecting end fed half wave verticals for those two bands today.  We are using LNR PAR EF-17 and EF-15 antennas mounted on two fiberglass poles.  Below is the 17 meter version.

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Preliminary testing has been successful when compared with the yagi/tuner combination.  We attempted to answer cq’s from Japan with the yagi on 17 meters to no avail.  Switching to the end fed half wave produced an immediate qso with JN8QNF.

Adding A Tuner To 20 Meter Yagi.

By adding a tuner to the 20 meter antenna system it is now possible to operate on 15 meters, 17 meters, and 30 meters in addition to 20 meters.  The 20 meter yagi acts like a dipole on the new bands.  No gain or much directivity but a dipole at 60 feet is a big improvement over the verticals that have been in use.  The tuner is a LDG Electronics model RT-100 remote automatic tuner mounted in the shack. This is similiar to using the tuner in a transceiver except this has wider coverage.  A conjugate match can be made anywhere along a transmission line.  However, any time a tuner is located at other than the antenna feed point there is loss introduced in the form of coax loss due to swr and cable loss.  This is an experiment to see how well the concept will actually work in practice.

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Our installation consists of 160 feet of LMR 400 coax between the transmitter and the antenna feed point (100′ to the base of the tower and 60′ up the tower).  If the tuner was moved to the base of the tower 100 feet of coax would be bypassed.  For these calculations we use the KV5R.com web site.  At 17 meters for example, total loss at 160 feet is 2.8dB (coax loss plus swr loss).  For 25 watts out from the transmitter the antenna would receive 13 watts.  Moving the tuner to the base of the tower would improve the loss to 1.2dB. The antenna would receive 19 watts.  We ignored the loss in the  100 feet of coax from the transmitter to the tuner.  That loss would be .5dB (or 3 watts in this example) with virtually no swr loss.  Therefore the coax would deliver 22 watts to the input of the tuner and the antenna would receive  3 watts less..  With 1.2dB of loss the antenna was receiving 19 watts.  Now it would receive 16 watts.  In conclusion if we moved the tuner to the base of the tower the antenna would receive 3 watts more power  or .5 dB (16 watts vs 13 watts).  Is it worth moving the tuner to gain 3 watts (or .5 db)?

SWR Loss at 18.100 MHz

 100′       LMR400     =     3 watts

Update:  It seems to work on 17 meters.  FT8 contacts with Europe have been made.  For the next experiment it would be fun to try a better tuner, such as the MFJ 998RT, at the base of the tower.  This tuner would have less loss plus allowing bypass mode and tuning a wider range.  It is expensive and putting a up a second antenna might be less money.

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.

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  • 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.

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The coils are wound:

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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.