Saturday, January 21, 2017

Quirky Keyer - The MFJ-493

The MFJ-493 has some cool tricks and some not so cool flaws

MFJ-493 "Super" Menu Driven Memory Keyer

Memory keyers do the repetitive and boring stuff

The bands have not been kind in this declining sunspot cycle and I've been sending out my call repeatedly on occasions before receiving a response.  I wanted to get a memory keyer to lessen the burden of repeatedly sending my call and to also give me opportunities to do a bit of contesting this year.

If you want a good memory keyer, the K1EL Winkeyer is the natural choice to go with, so of course, I chose to acquire a 23 year old MFJ product instead.   

Take the road less traveled and you'll find wonders or fall in a ditch, I always say

The MFJ-493 is no longer sold but you'll frequently see them available used for reasonable prices and MFJ still sells a less featured variant (the MFJ-492).

Memory keyer at the the ready

Features

Typical of many memory keyers the MFJ-493 let's you store messages in up to 8 memories of 4,000 character each using your paddle, an external keyboard plugged into the back or a terminal program via the serial interface.  If you make a mistake while entering a message you can send 8-DITS and it will erase the previous word and send the last word in the message so editing is fairly easy.  Messages can be constructed from other memories, i.e. you can store your call in Memory #1 and then use "/1" in other messages to reference your call.  Repeats and timers are available within the messages as well.

Any of the 8 messages can be sent with the press of a button, although to send messages 4-8 you switch to the second bank of memories.

I won't list all the features because I think they are relatively common across memory keyers and I've posted a link to the manual later in the post, but I will mention that I enjoyed the ability to vary the character AND word spacing sent in messages.  So you can create "Farnsworth" type messages that sound (to my ears) far more natural than the typical "squashed" sounding CW sent from most memory keyers.  I demonstrate that in the video review.   I know a contester would never want to slow down the CW sent from his memory keyer but I have different priorities.

Most of the functions are clearly visible on the front panel so you don't need to refer to the manual to operate most features.  Some of the commands are not listed on the front panel so don't totally ignore the manual.

Back panel
The back panel sports a couple interesting ports.. an external keyboard interface and a serial port interface.  The external keyboard can of course be used to generate Morse code without a paddle and can make programming memories easier.

The serial port can be used with a terminal emulator like PuTTY set to:

  • 1200 baud
  • 8 data bits
  • 1 stop bit
  • no parity
  • xOn/xOff flow control.


If you power up the keyer while it's attached to a terminal emulator you can see some interesting information:
MFJ-493 MEMORY KEYER VERSION 1.1.2C.        COPYRIGHT MFJ ENTERPRISES, 1993.
TYPE "[help]" (USING BRACKETS AND LOWER CASE LETTERS) FOR ON LINE HELP INDEX.
[help]
HELP INDEX FOR MFJ-493 MEMORY KEYER
1.  TYPE [help-program] FOR HELP ON PROGRAMMING MESSAGES
2.  TYPE [help-transmit] FOR HELP ON SENDING MESSAGES
3.  TYPE [help-setup] FOR HELP ON CONFIGURING YOUR MFJ-493
4.  TYPE [help-list] FOR LIST OF ALL COMMANDS
[help-list]
HELP-LIST INDEX FOR MFJ-493 MEMORY KEYER
[help]           LISTS GENERAL TOPICS
[help-program]   LISTS MEMORY STORING INSTRUCTIONS
[help-transmit]  LISTS TRANSMITTING INSTRUCTIONS
[help-setup]     LISTS KEYER SETUP INSTRUCTIONS
[help-list]      LISTS ALL COMMANDS
[start#]         STARTS KEYER MESSAGE NUMBER # STORAGE ROUTINE
[stop]           ENDS KEYER MESSAGE STORAGE ROUTINE
[{#}]            MARKS FILE FOR ASCII UPLOAD TO MEMORY
[send#]          SENDS MESSAGE NUMBER #
[show#]          DISPLAYS MESSAGE NUMBER # CONTENTS
[co]             STARTS KEYER COMMAND MODE
Among other commands.  There are also commands for printing out the contents of the memories.
So the keyer has a sort of built-in manual if you connect it to a terminal.  Very full featured at used prices.

Using a terminal to the keyer via the serial port also displays everything you send with your key as well as allowing keyboard (terminal) input to the memories or allowing you to send code by typing in the terminal emulator.

Lastly regarding commands.. a useful command to know that's not on the front panel, is that you can reset the 493 to factory settings by holding the menu button down while turning it on.


Cool features not seen in other memory keyers

Two functions FCC Exam Practice and QSO Simulator are lots of fun.  The FCC Exam practice sends a standard FCC CW exam from back when code was required for license upgrades.  It varies up the messages but sends the standard elements required back then.  Good for practice.

But the super-cool feature is "QSO Simulator". This mode performs an interactive QSO with you.

Are band conditions getting you down?  No one answers your calls?  Have a QSO with your keyer!

I'll leave the video to do most of the explaining but basically, the keyer will listen to you send CQ and answer your call and then exchange information with you answering after the turn around.  You're expected to get the call it SENDS you correct or it won't answer you back.  If you send poor CW it makes raspberry sounds at you.  It's just a lot of fun to play around with and copy.

MFJ-493 "QSO Simulator" demonstration




Nits

A couple features that are completely useless are the "hand key" mode and the "semi-automatic-mode".   Once the hand-key mode is enabled you can use either paddle as a straight key but it is very unresponsive at anything over 5-10 wpm.  So keep your straight key wired into the output of this keyer.  Similarly the "semi-automatic" mode is supposed to simulate a bug, where the DITS are sent automatically but the DAHS are manual.  Well it's even worse than the hand-key mode, don't bother as it's for entertainment purposes only.

Another problem with this keyer is related to the weighting commands 'C' and 'W'.  If you have either of them set to a value other than zero you cannot accurately record a message into memory using the paddles.

I'd hoped to be able to run both my paddle and bug into the input of this keyer and switch it to hand mode when I wanted to use the bug and use it as a bug "de-scratcher" but it doesn't buffer the bug input and in hand key mode misses about a third of the DITS sent by a bug so no joy there.  I'll just keep using my old Ham-Keyer as my bug de-scratcher.

MFJ-493 Manual

Many thanks to Paul/N6MGN for sending me a copy of the manual and schematic for this keyer so I could share them.

View manual
Download manual

View Schematic
Download Schematic

So many connections

Adding this additional keyer finally made me break down and build a connection box for all my keys and rigs.  I have 4-5 CW keys on my desk at any given time and 3-4 radios.  Each of the two external keyers have female RCA jacks for output.  The Ham Keyer uses 2 independent 1/4" inputs for straight key and paddle while the MFJ-493 uses a 1/8" stereo plug for the paddle.  The Ham Keyer expects the DIT to be the tip of the plug and the MFJ (by default) expects the DIT to be the ring of the plug.

Arrrgh!

To top it off, each of my primary 3 radios expect different wiring from an external keyer.  
  • The Elecraft KX3 needs a 1/8" stereo plug with the ring terminal un-grounded
  • The TenTec Eagle needs a 1/8" stereo plug with the ring terminal grounded or a mono 1/8"
  • My TenTec Century/21 needs a 1/4" mono plug (my rig is modified, I believe a stock C21 needs a male RCA
So I took a project box drilled it for 5 phono jacks wired in various configurations for each of the rigs and keyer inputs.  I still can't leave the KX3 key plugged in when not in use because when that radio is turned off it presents a high impedance on the plug and makes the C21 think the key is down...  (nothing is ever simple) but now I don't have a bunch of 1/4" to 1/8" and stereo to mono plug connectors chained together like a box-cars on a train.


Video review

This video review demonstrates a few of the features and contains the same QSO in the video above at the end...



Summary

The MFJ-493 is a feature rich yet somewhat flawed keyer.  For the price I think it's a good buy but don't expect some of the more esoteric functions to work up to your expectations.



That's all for now

So lower your power and raise your expectations... and send your call a couple dozen times using a memory keyer

72/73
Richard AA4OO

Wednesday, January 18, 2017

Callsign lookup when portable

Obtaining callsign info when portable

When I operate portable I travel light and don't take a computer but I do carry my smartphone.  As long as I have a signal I can lookup callsign information using my phone.  One clean and simple website I've found to use while mobile is https://callook.info  

However a big drawback is that it is only for US stations because it is using the FCC ULS.  To lookup a US callsign call keep callook.info in one of your browser tabs open.

cal look.info website

QRZ.com?

QRZ is one of the more popular websites for looking up callsigns but the website is not formatted for use on mobile devices.  It can be used but pinch-zoom is required and honestly the ridiculous number of blinking ads on the website is obnoxious so I stay away from it as much as I can.

Here's what QRZ.com looks like on my mobile phone...

Ugh!

There's an app for that...

These days there's always "an app for that".  There are a number of mobile apps that can lookup callsign information as well.  I've used QRZDroid with success and it is not limited to US callsigns.  I'm confident there's something equivalent for IOS devices.


QRZDroid mobile app

That's all for now

So lower your power and raise your expectations

72/73
Richard AA4OO

Sunday, January 15, 2017

Have KX3 - will travel

Porch Portable

During a break visiting relatives in Western NC I went outside and threw my end-fed antenna up into a tree and sat on the front porch swing and worked stations in Maine, Kansas and Cuba.


Elecraft KX3 -- Palm Single Key -- and Index cards for logging 


Portable Ease

The Elecraft KX3 is such a fabulously portable radio.  It is very totable with sidekicks panels and cover, the only exposed part during transport is the BNC connector.  I just make sure that's pointing "up" in the backpack.  I didn't take the time to put the internal batteries back in the KX3 so I carried a small 3ah gel cell battery, good for hours of operation.  My antenna is a 9:1 balun fed insulated wire.  I get it up in the tree using a throwing weight and heavy line, then untie the weight, attach the wire and pull it up.  The coax serves partly as a counterpoise, and I clip two more wires cut to different lengths for additional counterpoise.  

The KX3's built-in auto-tuner will tune a spoon so it was no problem tuning the end-fed

Operating

The North America QSO party was in full swing and I was looking for casual ragchews so I headed to 30m and heard a number of QSOs but signals were not strong.  Checking RBN from my smartphone I saw that I wasn't getting very good reverse beacon reports.  

Reverse beacon reports while operating portable

After sending my call out manually a few times I put the KX3's built in keyer memory to work sending out my call and eventually I received answers to my calls.

I only had about 90 minutes to operate but I had a good time working a few stations and listening to other QSOs.  Packing up the radio,  key and pulling the wire down didn't take long.  

I'm still thrilled to have the Elecraft KX3 for such opportunities.


That's all for now...

So lower your power and raise your expectations

72/73
Richard, AA4OO

Wednesday, January 11, 2017

Get a grip

The Navy Knob exposed

One of the more popular CW straight keys in the venerable Navy Flame Proof.  You grip this key using its Navy style knob.  The "navy style" is tallish and rounded on top, usually with a skirt underneath.  I demonstrate the "grip" used for the Navy style key in an earlier post.

But what's this old knob made from?  Compressed horse hair and tar?

Navy Flame Proof Key contains "fillers" in the bakelite material
As I photographed the key I noticed that up-close the knob of my old service key appears to contain fibrous material and it got me wondering about what material they used to make these knobs...

This knob is made of Bakelite

Bakelite is interesting stuff.  It was one of the first commercially successful "plastics" developed by the Belgian-American chemist Leo Baekeland in Yonkers, New York in 1907.  Leo incorporated "filler" materials in bakelite to give it strength.  

All sorts of ground up stuff went into bakelite including asbestos.  

So maybe my "Flame Proof" key really IS flame proof...

Bakelite factory

On the other "hand",  here's the Kent Hand Key knob for comparison...


Kent Hand Key up-close-and-personal


That's all for now...

So lower your power and raise your expectations

72/73
Richard AA4OO

Sunday, January 8, 2017

My TenTec Eagle sounds better than my Elecraft KX3

Your eardrums will thank you

Coming back to the hobby in 2015 I re-entered as a CW / QRP operator and I searched for a good QRP radio.  The Elecraft KX3 certainly qualified and it has been a great radio to use, especially when portable.

Elecraft KX3 -- stellar radio for portable QRP operations

But a few months after getting my KX3 an old TenTec Century/21 found it's way onto my desk and through numerous blog entries you may note that for some reason I kept gravitating to use it rather than my KX3 when I operated from the shack, even though the KX3 beats the old C21 technically in absolutely EVERY regard.  I just enjoyed operating CW with the old radio more than the KX3. I couldn't explain why.

Fast forward to late March of 2016.  I purchased a used TenTec Eagle from my friend AA4XX and began using it as my primary radio when I wasn't portable.   Here again the KX3 trumps the Eagle in nearly every technical aspect and offers dozens more features.  I just kept gravitating to use the TenTec radios rather than the Elecraft.

I used the my KX3 for Field Day in 2016 and after I packed up and brought it home the KX3 stayed in my backpack and only came out for portable outings.  It did not go back on my desk.  The KX3 cried little electronic tears while the Eagle gloated...

Ten-Tec Eagle -- compact / simple HF transceiver

Why no love for the KX3?

Time passed, and over the new year break I got to thinking about what I missed about having my KX3 on the desk; like its RX/IQ output for HDSDR and the ease working DX splits using it's dual watch capability and it's integration to logging applications like the ability to trigger CW macros from my logging software.  The list of "nice-stuff" goes on and on since the KX3 contains multiple kitchen sinks...  So I re-organized my desk to make room for the KX3 again and operated with it exclusively over the past few days...

I was getting ear fatigue and my ears rang in the evenings.  This was not the sort of ringing in the New Year that I wanted. I had been previously operating the same amount with the Eagle over the past month without the earaches.  Something was amiss.

Had I finally discovered why I keep going back to my TenTec radios?

Audio, Audio, Audio

So over time, even when I switched back and forth between radios there was a subtle "ouch" occurring when I used the KX3.  I enjoy CW and digging out weak signals can be fun... or it can be painful.  I guess when I sat down to use a radio and my hand hovered between the "Oh-so-feature-rich" KX3 and the "Nice-personality" Eagle my brain was saying "choose the nice personality" you're happier that way.

But there was a underlying reality to the choice I was making.

Just the facts mam

I used an audio frequency analyzer to capture audio from each radio by sandwiching the microphone in my headphones.  It hears what I would hear.  And the graphs tell a tale.

Below is one graph for each radio.  The RED graph line in each chart is the averaged "peaked" frequency output audio during the same QSO.  Ignore the green line as it was just the instantaneous  audio at the time I froze the display between takes.  The CW sidetone on each radio is set to 620Hz.

I re-ran this capture for each radio a few times during a lengthy ragchew between two stations.  The signal strength was around S5-S7.  It wasn't a strong signal which is typical of what I work, especially as the Solar cycle winds down.

I tried the captures with and without noise reduction on each radio.  The RF was rolled off as evenly as I could determine for each and both were set to a DSP filter bandwidth of approximately 400Hz.  Both radios were using the same antenna and everything was as similar as I make it.  RCVR EQ was set flat for the KX3.



Elecraft KX3 CW audio (ignore green graph line)
Ten-Tec Eagle CW audio (ignore green graph line)

The CW audio output from each of the two radios is distinctive

KX3 audio demonstrates
shoulder noise
Eagle has clean audio
There's clearly a CW signal peak around 620Hz in each radio but the KX3 shows a significant shoulder of audio just 9dB down from the peak below the center frequency 

Whereas the Eagle has a clear peak presenting a narrow tone range at the sidetone pitch with narrow shoulders down to the filter width.





Confirmation of my subjective tests

When I saw this I literally said "Aha!"   

This confirmed what my ears and my subconcious had been telling me.  The KX3 is more fatiguing to listen to than the Eagle because it presents more noise in the audio or at least a wider audio signal given the same DSP filter setting.  I've always remarked about my TenTec radios that their CW seemed to float above the noise.  I believe it's related to the cleaner audio filtering. The TenTec Eagle just has cleaner audio out of the box. It has no audio adjustments beyond AF and NR, no menus for fine tuning.  My old TenTec Century/21 sounds the same when using its 500Hz selectivity setting. 

In my opinion Ten-Tec just got CW right.

Yes, I have tried using the KX3 RCVR EQ settings to reduce that lower frequency noise and the problem IMO is that the EQ is more for SSB audio.  I think the Q for each setting is too broad and when I try to reduce the low frequency noise IMO it just makes the audio sound mushy.  I just can't get as "clean" sounding CW tone out of the Elecraft as I can the Ten-Tec.

OK, "sound" is a subjective thing.  No two people will hear the same thing the same way and frequencies that bother me may not bother you, but it seems pretty clear from the graphs that the CW audio from the KX3 doesn't match the Eagle.

Summary

Admittedly, my test involved a very small sample size of one radio from each manufacturer.  It's just that I'd put the KX3 back on the desk after a many month absence and my ringing ears got me to investigate the cause a bit more scientifically.  

I will continue to use the KX3 for portable ops because it is a great self-contained radio and when I work portable I usually operate for much shorter periods so the audio doesn't become an issue.

Man, I hope Ten-Tec can come back from the grave. They sure made some fine radios for CW operators.


That's all for now...

So lower your power and raise your expectations

72/73
Richard AA4OO


Saturday, January 7, 2017

What's in your log?

Peeling the ADIF onion

I try to keep a log of my contacts, mostly to know if I've previously worked someone and for keeping up with my SKCC awards.  I also keep notes from each QSO in my log so I can reference them during followup contacts. I'm not a contester or a DX chaser although I occasionally will take a look at the cluster spots and see if I can work someone across the pond if they're sending slow enough for me to copy.

Mostly I just send out my call and see who turns up. 

But with the new year I was curious about how many States I'd worked in the past year and a half, during casual contacts.  Turns out I've worked all US states except Nevada and Nebraska (but I could swear I've had QSOs with Nebraska).  Unfortunately my logs are incomplete.  I've had computer screw-ups where I've lost logs and for about 2 months last year my logging software stopped working due to a Windows 10 update issue and I kept trying to log using the QRZ online site but I found it difficult to use.  Also, when I'm portable I rarely transfer my paper records back to electronic logs.  I usually just scribble down some notes during my Portable QSOs.  So I'm likely missing a few dozen QSOs here and there.  I know I should get my logging act together but then the hobby starts to seem like work.

Anyway, poking through my log led me to wonder if I could generate some statistics.  I'd previously written a Python application using python hamtools after my first 100 QSOs to parse my log and determine the average age of operators that I'd worked.  I wrote about those results in http://www.hamradioqrp.com/2015/09/morse-code-is-only-mostly-dead.html  But I couldn't find the program I wrote back in 2015 (I'm not very organized) and as I started to write a new parser it got me thinking there must be existing applications to analyze my log and provide insights.  

So how do you analyze your log file?  By exporting it in ADIF format.

ADIF

ADIF stands for Amateur Data Interchange Format.  Most Ham logging programs can export and import data using this format.  It can have lots of fields here's an example record:

<a_index:1>7 <ant_az:3>334 <ant_path:1>S <state:2>MI <band:3>30m <call:4>K8BZ <cont:2>NA <country:13>United States <cnty:7>GLADWIN <cqz:1>4 <distance:4>1045 <dxcc:3>291 <eqsl_qsl_rcvd:1>R <eqsl_qsl_sent:1>R <freq:8>10.11403 <freq_rx:8>10.11403 <gridsquare:6>EN73SX <ituz:1>8 <lotw_qslsdate:8>20170105 <lotw_qsl_rcvd:1>R <lotw_qsl_sent:1>Y <mode:2>CW <my_country:13>United States <my_cq_zone:1>5 <my_gridsquare:6>FM05OP <my_itu_zone:1>2 <my_name:4>Rich <name:25>Steven C Wuelfing (Steve) <operator:5>AA4OO <station_callsign:5>AA4OO <qso_date:8>20170103 <qso_date_off:8>20170103 <qth:7>Gladwin <rst_rcvd:3>599 <rst_sent:3>569 <rx_pwr:1>0 <time_off:6>191503 <time_on:6>185344 <tx_pwr:2>5 <k_index:1>3 <lat:7>43.3504 <lon:8>-84.5603 <notes:97>rig ic7600 ant g5rv, rainy temp 38f, lil snow, left hand sending with single lever, likes my pics <pfx:1>W <sfi:2>73 <app_log4om_validated_callsign:1>Y <eor></eor></app_log4om_validated_callsign:1></sfi:2></pfx:1></notes:97></lon:8></lat:7></k_index:1></tx_pwr:2></time_on:6></time_off:6></rx_pwr:1></rst_sent:3></rst_rcvd:3></qth:7></qso_date_off:8></qso_date:8></station_callsign:5></operator:5></name:25></my_name:4></my_itu_zone:1></my_gridsquare:6></my_cq_zone:1></my_country:13></mode:2></lotw_qsl_sent:1></lotw_qsl_rcvd:1></lotw_qslsdate:8></ituz:1></gridsquare:6></freq_rx:8></freq:8></eqsl_qsl_sent:1></eqsl_qsl_rcvd:1></dxcc:3></distance:4></cqz:1></cnty:7></country:13></cont:2></call:4></band:3></state:2></ant_path:1></ant_az:3></a_index:1>

A web search for ADIF parsers and generators abound.  There was a promising Excel macro but it didn't work for me.  A bit more searching turned up a really cool site...

QScope to the rescue

QScope (https://qscope.org) is a website that allows you to upload your ADIF file and provides a bunch of statistics and charts.  There is standard stuff like "Stations worked", "Bands" etc. and for contesters there are statistics for QSO rates (i.e. how fast are they logging contacts).  I was actually more interested in how many of my QSOs were over an hour but it didn't have a statistic for that :)

So here is a small sample of statistics and charts that QScope was able to tell me from my log...

Basic Statistics

Number of QSOs 1304
Number of Dupe QSOs (same Call, Band, Mode) 254
Imported on 2017-01-06
First QSO at 2015-07-29 19:25:17+00
Last QSO at 2017-01-05 00:04:46+00
Event duration 525 days 04:39:29
Distinct callsigns 911
Distinct CQ Zones (if specified in the ADIF log) 20
Distinct ITU Zones (if specified in the ADIF log) 24
Distinct DXCC (if specified in the ADIF log) 56
Distinct Locators/Grid Squares (if specified in the ADIF log) 863

 QSOs per band




Where is your antenna beaming?

This chart is very interesting to me.  It shows that 93% of my QSOs are from antenna bearing between 270-300 deg.   An OCFD and a Doublet should not be this directional so I'm very curious.



Cool stuff with Maps

The Google map KML support is impressive.  You can download KML files generated by QScope and watch animations of your contacts over time and groups of stations contacted in each DXCC region.



Summary

There's a lot of information in your log.  So if you're a new operator like me take some time and determine if there are states you haven't worked or if there's a state you overwork (most my contacts this past year were in Ohio).  

For starters I'm going to figure out if there are SKCC operators in Nevada and Nebraska that I can schedule some QSOs with to complete my WAS.  I'm not looking for an award or a plaque, I just think it would be cool to say that I've worked every state in the US QRP.


That's all for now

So lower your power and raise your expectations

72/73
Richard AA4OO

Wednesday, January 4, 2017

The ground is not beneath your feet

Yet another article about proper grounding (yawn)

It seems as though one of the biggest misunderstandings in amateur radio is the issue of "grounding". I have probably read more than a dozen articles about grounding and sprinkled a little from each regarding setting up my station.  But there always seems to be more to learn.  This time I learned more about electrical grounding rather than RF grounding.

Situation

I generally try and send my CQ calls at 5 watts RF output or less. If I receive a really poor signal report from the answering station I'll raise my power if I'm able to 20-40w to give them 6-12 more dB to make it more pleasant for them to work me.  Propagation has been really poor for me over the past few weeks and I've found myself getting lots of 339, 459 reports etc. and I've been using the Eagle to bump the power into QRO range of up to 80 watts sometimes (gasp).  

However whenever I raised my power in such a situation my TenTec Eagle would behave oddly...

After I'd finish keying there would be a brief audio drop and sometimes a pop as the audio came back.  I thought an under voltage situation was occurring so I measured the voltage from the power supply to the rig while transmitting into a dummy load.  The voltage only dropped from 13.8v down to 13.6v so that didn't seem to be the problem.  Even transmitting QRO levels into the dummy load sometimes resulted in the audio pop but it was always after I un-keyed, never during the actual transmission.

I was perplexed.  So I put my question to the TenTec Eagle Yahoo Group.  Over the past year I have learned more from the technical discussion in that group than pretty much any other single forum...  A frequent contributor to the TenTec Eagle Yahoo Group, Bob, K4TAX, answered my question:
Yes, the Eagle chassis is "floating up" that is to say the DC negative is not really at zero volts as current increases with higher power.   I suggest a dedicated ground from the Eagle chassis ground terminal to the power supply ground terminal.  For all of my ground jumpers I use #10 AGW auto primary wire to which I crimp and solder a proper lug to each end...
I did already have the station ground connected to the AC service ground via a fused connection but it was a small guage wire and apparently insufficient to tie the radio back to the power supply ground.  So what did this mean?  Bob, K4TAX followed up with an email a couple days later to see if I'd resolved my issue...
 Many, I find, believe the DC Negative is adequate between the radio and power supply.   In as much as the radio ground system internally has in effect two ground systems, one being for digital ground and one being for analog ground, we commonly find that the resistance between the power supply and the analog ground does allow the radio to float up above zero volts when in transmit.  To test for this condition, measure the voltage between the power supply ground and the ground terminal on the radio.   Put the radio in CW and key down.  The voltage should be less than 0.25 VDC.   If it is greater than this, the voltage drop is caused by the resistance in the DC power cable or the ground method used for the station.    For this reason it is strongly suggest one have a dedicated ground connection between the radio and the station power supply.  
When I performed this measurement I saw that the DC negative between the radio and the station ground was in fact "floating up" by more than 0.5 VDC.  When I shortened the DC cable to only 18" between the power supply and the rig that resolved the float but the proper answer was addressing my DC electrical ground.

Station and A.C. Electrical Service Grounding





  1. If not already in place, add Chassis Ground terminal to your Power Supply, and internally bond chassis ground to D.C. negative terminal.
  2. Connect all station equipment chassis grounds direclty to P/S chassis ground. See Figure 1 below.
  3. P/S MUST have three wire A.C. connector, plugged into mating receptacle with ground tied back to A.C. Main Service Entrance ground.
  4. The P/S chassis ground is your Station ground. The A.C Power connector ground bonds to your A.C. Main Service ground.


Figure 1 below depicts ground wire from each piece of equipment is tied back to the Power Supply Chassis Ground.

The Power Supply MUST have Service Ground on A.C.Connector to complete an effective Station AND Service Ground.




The fix


My station grounding was somewhat haphazard.  As I'd added equipment I'd added ground straps between new components and whatever was nearby.  I had different gauge wires, and sometimes used RF straps for DC grounding and... well it was a mess.  Armed with new knowledge from Bob I went to Home Depot and purchased 50ft of #10 AWG with #10 AWG terminal eyes and #10 AWG butt connectors.

I cut a 6ft piece of the #10 AWG wire and every 18” along the length solder/spliced in a 10# AWG wire adding a butt connector resulting in 18” jumpers that allowed each piece of equipment to be attached via a jumper with the butt connector. Each jumper had a male butt connector on one end and a terminal connector to connect it to station grounds at the other.  That allows me to easily move equipment around the station ground without unscrewing the ground lugs.

I now have all the radios, tuner, switches and power supply bonded together properly. I also bonded to the chassis ground of my filtered power strip that feeds AC to all the components.

Also at Bob's recommendation I disconnected my station from the separate ground wire that ran to my outdoor ground rods.  My outdoor OCF Dipole comes back through an Alpha Delta spark arrestor that still ties into that ground rod system which is also tied into the house service entrance ground.  

The result

I'm happier than a slinky on an escalator... Ok I've used that one before but it's applicable again.
  1. First, there is no longer a rats nest of ground wires running between everything.  Ok, points for neatness.
  2. I can individually disconnect a component without removing the ground wire through the removable butt connector.  Points for not fighting with the ground lugs when I need to pull a component or re-configure the station.
  3. My Eagle can run QRO up to 100 watts out if required with no DC floating issues.
  4. Here's the phenomenal bit... the band noise at my station is now One S-units lower on 40m and 20m and Three S-units lower on 30m.  Honestly I have a hard time believing that re-working the DC ground and disconnecting from the long outside ground wire made that big a difference in my noise levels but it has.

Summary

There is so much to learn in this hobby.  My "aha" moments just keep coming.

So if you're like me and didn't know that your radio may have separate Negative VDC voltages between its power and its chassis and what the ramifications could be if they were unmatched, well now you know.  Just a few Ohms difference between the power supply negative ground and radio chassis ground can have side effects inside your radio.  You may not even know there are problems brewing inside there, so ground that station properly for VDC!

Also, if you're running a long ground wire to your station separate from your AC mains safety ground then you're creating a ground loop of at least a few Ohms that gonna cause problems.  

I am not saying that you shouldn't (if your run to ground is short enough) run a ground for an antenna grounding system.  But that is RF grounding and its a very different topic.


That's all for now...

So get rid of that long ground wire, properly ground your station to your power supply and make proper use of your AC mains safety ground.

72/73
Richard AA4OO