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.


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.




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.


(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


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.


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.