Christmas Tree Antenna

WA1ABI, John, in Portsmouth invented a new mode a couple of years back — Christmas Tree to Christmas Tree QRP.  Today I had my outside tree wired up to a remote antenna tuner and gave the XMT2XMT mode a try.  The photo below shows the remote tuner in the circled area on the bottom left.

TreeFeed

The photo below shows the tuner to Christmas Tree light feed — BNC to Banana Plug to Alligator Clips to the plug end of the lights.  The green extension cord is disconnected but the U Ground pin can be used as an earth ground if needed.

Feed2Tree

And, of course, my trusty KX3 running the show (LDG Remote Tuner box on the right — note I didn’t want to waste power in the feedline by using the tuner in the KX3)

Rig

While I wasn’t able to raise WA1ABI, or Bruce NJ3K, I heard them both, and the RBN was hearing me.

The oldest RBN was with feedline across prongs of lights.  Newer entries were with hot lead of feedline onto one wire of lights, and the shield to AC Power Ground via extension cord.

XMTREE

Here is an audio recording of Bruce and John in QSO.  All of us were running KX3s and using Christmas Trees for antennas.

 

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K1 Assembly Burp #3

I spent 65 minutes fabricating three SMT replacement for a SA612AN chip that is no longer available in through-hole.  The process involved in stripping 24 1″ wires, somehow holding them in place while soldering them to an adapter that is about 0.3″x0.4″, not having the wires fall out of the holes during the process, not shorting them out, etc, etc, etc.

Had the DIP parts been available (and they are in small quantity from several vendors on the internet like this on:  http://www.thepartsplace.k5nwa.com/index.php?route=product/product&product_id=164 ), three of them would have taken 5 minutes to solder to the PCB.  But in fairness to Elecraft, they are not available in the larger quantities.

So Elecraft did a smart thing by making an adapter to use the SMA chip (something I have done many times for end-of-life products in my work place).  However Elecraft burped big time by not doing one simple thing — putting the holes on standard 0.1″ spacing, and using a dual male header.  This would have saved at least 45 minutes of assembly time.

So add another 27 components to the assembly and 65 minutes.  Here are the basic items required for each chip (insulated wire is stripped and cut to create 8 legs):Burp-3-1

Somehow the adapter has to be held, the wires kept in place, and solder applied without shorts — easy to do if you have four steady hands.  Almost impossible with two.  So I used needle nose pliers to hold the adapter, and put it into my PanaVise so that it was mostly parallel to an arm, which acted as the stopping point preventing the wires from falling out. Note: Elecraft’s suggestion of bending the wire at the top is NOT practical as the wire will rotate and create shorts between pins.Burp-3-2

The final Rube Goldberg product looks like this (very un-Elecraft-like:Burp-3-3

In the spirit of not complaining without providing a solution, how about something like this (SMT adapter PCB mated to 8-pin screw machine male-male adapter?K1-Burp-4

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Another Surprise From the ARRL

I guess the January 2016 QST is hot off the press.  I received an express envelope with three pristine copies today as a courtesy for a brief piece in Technical Correspondence [pages 72 & 73].

My father was a journalist, working for the Lexington Herald Leader for many years after owning a small weekly paper in Tennessee.  If he were still with me, I suspect he’d be smiling.

QST Jan 2016

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K1 Assembly Continuing

The K1 RF Board assembly continues to move forward.  Today, 24 components were installed in 70 minutes.  Only a third of the RF board remains, with a bit under 16 hours spent so far.

IMG_3604

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K1 Assembly Burp #2

I had a chance to install a dozen components today, but it took about 50 minutes.  This was because the two adjustable caps (C13 & C20) as supplied do not match the manual description or silkscreen outline.  Elecraft specifies a particular mounting orientation.

Examination of the schematic shows that both caps are trimming oscillators, and neither leg is ground referenced, so I’m not sure why there is a concern over orientation.

Like many small trimmer caps, the adjustment screw (rotor) is attached to one of the two pins, and the stator is on the other.  So approaching the screw might couple in some stray capacitance making it hard to set things.  Usually one tries to have the rotor ground referenced to avoid that.

In both cases, one side of the cap is attached to the crystal, and the other is going into a pin on the SE612 mixer/oscillator chip.  While I don’t think it will matter much, I figured avoiding having the rotor end on the crystal would be best.  In the photo below the stator is colored red and is a rectangular bump, so maybe that is the “flat” side.  in any event, the flat side on the silk screen goes to the crystal.   So this is how I installed them, red side to the flat.

K1 Burp 2

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K1 RF Assembly Continuing

After 2 hours 20 minutes of assembly time, there are 81 components on the RF board (a rate of about 1.75 minutes a component).  With 251 total components on the RF board, I’m about a third of the way away.  Some 48 of those (transformers and SMA chip adapters) require quite a bit of fiddling.  So call it another 5.5 hours of assembly time to go.  As I have 14.5 hours invested so far, that would be a total of 20 at the current rate.

RF at 2h20m

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K1 RF Board Assembly Underway

It’s been about 5 days since I did any work on the K1.  This time of year it’s important to keep the family happy, and that means lots and lots of Christmas decorations.  I hate the thought of landfilling the many sets of lights we use each year, so I insist on repairing them.  This year I replaced several hundred lamps, which occupied my time for several days.  But the lights are up, the house is festive, and my time is my own again.

Today I began the assembly of the K1 RF board.  I estimate that this one card is about half the total assembly effort — lots of parts.  But I surprised myself today by spending about 70 minutes to install 40 components; under 2 min/part.  When I did the inventory of the RF board parts, the tiny caps were a devil to read, so after accounting for each one, I put them into individually labeled bags.  I still verify them, but at least I don’t have to look through dozens of identical looking caps to find the one I need.  And I discovered that the resistors, which had been sequenced on tape as if for automatic assembly, were in the order that they are installed.

RF Begin

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SCS DR-7400 Modem and the Icom IC-9100

I haven’t been able to get my Icom IC-9100 and SCS DR-7400 P4 modem to play nicely together.  No matter what I’ve tried, the modulation level was too high, showing substantial ALC action, which would lead to a distorted transmit signal.

Some investigation last week indicated that the DATA2 connector on the back of the IC-9100 expects a VERY low level of audio, something on the order of 30 mvpp.  The minimum audio output level on my DR-7400 is about 41 mvpp (max is about 3200 mvpp).

The solution will be to make a small adapter cable (Male miniDIN-6 to Female miniDIN-6 — the same connectors used on a PS2 keyboard extension cable) with a voltage attenuator built in.  Something on the order of a 470 ohm resistor across the IC-9100 audio input line and ground, with a 3300 ohm resistor in series to the audio out line of the DR-7400.   Combined with the 1K output impedance of the DR-7400, that will produce a 10-1 voltage division.  So 300 mvpp from the DR-7400 (one order of magnitude above the minimum and one order of magnitude above the maximum), will produce about 30 mvpp at the IC-9100 input (a range of 3 mvpp to 300 mvpp).

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A Surprise From the ARRL

A large envelope from the ARRL arrived this weekend.  It look suspiciously like the kind they send out awards for states or sections in various contests, but I didn’t recall submitting a log recently.  I was pleasantly surprised to find a nice letter and a certificate inside:

ARRL Author's Certificate

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K1 Front Panel Completed

The Front Panel assembly had 75 components and took 265 minutes of assembly and verification time.  That works out to 3.5 minutes per component and 4.4 hours.

At this point, I feel that I’m about halfway finished with the build based on the number of components installed so far.  If so, I’m at 8.7 hours of assembly time, which would double to about 17.5 hours.  Add in 3.5 hours of inventory time, and it looks like it will take 21 hours to assemble.  I have no idea how much time the testing/alignment will take, but 24 hours is seeming like a pretty reasonable estimate for a completed K1.

By the way, the K1 front panel is 5″ across, and 2.25″ tall — we are talking a tiny QRP rig!

FP Front Done

FP Top DoneFP Bottom Done

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