TEN-TEC Century 21 --- Vintage Novice CW Rig

TEN-TEC Century 21

A second HF rig has somehow found its way into my home.

Ten-Tec Century / 21 CW Only Transceiver

Since getting back into HAM radio with my focus now on CW and QRP I find that many of my contacts use old and/or homebrew equipment.  Maybe it's because I often call CQ with my straight key rather than paddles that results in most answers to my CQ being operators using a straight key or a bug.   It seems these operators tend to not use the latest piece of shiny gear, which made me an anomaly; sending with a straight key while using my SDR-in-a-box like the Elecraft KX3.  Maybe for this reason I've found myself being drawn to less sophisticated types of equipment.  I'm not talking about wanting to go back to spark gap and gravity batteries, but sometimes the KX3 is just too easy to use.

In the same way that I'd prefer to send CW using a Straight Key to a keyboard since it's a greater challenge, I think that the older, less sophisticated equipment can bring more satisfaction to the hobby.

Vintage... like bell bottom jeans and corduroys 

Now don't get me wrong, I'm not suggesting that the only "real" radios are those with discreet components or tubes, nor am I saying no key but a straight key.  I'm just moving through some stages of the hobby that I missed because I didn't grow up with this older equipment and I think the challenges can be fun to learn and operate.  

I didn't get into Ham radio until 2006 and the commonly available used equipment of the time was microprocessor controlled rigs with digital displays, optical encoders, DSP filters and seemingly endless menus for configuration.  I went through a few HF radios over a couple of years: a Yaesu FT-857, ICOM 730 and lastly, a ICOM 746 Pro, before I sold the radios and dropped out of the hobby. At the time none of those rigs held any "magic" for me, they were just tools with increasing levels of functionality and ease of use.   However the ICOM 730 did hold copious amounts of stale cigarette smoke and nicotine from the previous operator that it would release into my room as it warmed up.  Not really magic, more of a non-corporeal element let's say.

If you've read my earlier posts you may recall that although I like my Elecraft KX3 immensely I have some strange fondness for TEN-TEC equipment.  Ten-Tec has made some quirky radios with legendary full break-in QSK and supposedly smooth, quiet receivers for CW operators for a few decades now.  So when a Craigslist posting leaped into my browser window (I don't know how that happened) advertising a seemingly pristine late-70s rig that had supposedly been reworked to a perfection, all for $140, I just couldn't pass it up... well at least the price in the ad was accurate.

The Ten-Tec Century 21 is an interesting transceiver.  In the simplest sense it was an ideal radio for the Novice Licensed HAM operator of the 1970s.  It is a CW only transmitter.  It doesn't require fiddling with a resonant tank circuit of the typical tube radios of the era to work out resonance.  It has a built-in power supply that runs off 115-120v mains.  It doesn't use a superheterodyne receiver but a direct conversion receiver (Ten-Tec called it a double direct conversion receiver).  This resulted in a simplified design and good selectivity but without the IF there is no AGC so be ready to work those RF/AF gain knobs.  It also has easy band changing and nice filtering.  From web searches and reviews its most common problem is a PTO that has to be rebuilt every few years.  The Ham I purchased mine from said it had been rebuilt.  It doesn't slip (yet) but it's kinda stiff so I expect a PTO rebuild to be in my future.  I spoke with a ham I work with who has rebuilt one and he said it's not difficult, simply time consuming (but he repairs electronics all day so YMMV).

Operation is relatively simple:  

1. Start with the radio off.
2. Turn the Drive knob down (counter clockwise), select your band 
3. Turn the radio on by pushing in the RF Gain knob (it is the on-off switch).
4. Find and open frequency (wait, listen, wait again, listen) and while holding the Set Drive button apply just enough power using the Drive knob to give you some RF out for matching your antenna.  Better yet use a frequency analyzer to tune QRM free.
5. After you're matched up you can bring the power up to where you want to operate.  Unfortunately this can't necessarily be done into a dummy load unless you're match is near 1:1.  The SWR will affect how much output drive you can use.  If you're going to run QRP then no worries because you won't be running the power input up to a point that could trip the final, Maximum input power is marked by the thick line on the Input Power meter (about 70w).  This results in differing output wattage dependent on antenna resistance and frequency.  I found that into a 50ohm dummy load I could generate up to 40w output for 80m, 35w output for 40m, 30w output for 20m and so on, down to about 15w output on 10m.  As I plan to use the rig for QRP this is mostly academic.  It certainly can provide more than QRP output levels if conditions warrant.

To Tune a Station prior to the QSO

This seems more complicated than it should be but I'm guessing after I've done it a few dozen times it will become automatic.  

The Offset Knob

The CW tone you hear is the difference between the current PTO tuning and the position of the Offset knob.  The Offset knob can be an offset to either side of the current frequency (think of this as CWR depending on your band).  In other words the zero position of the Offset knob applies zero audio offset to the currently tuned frequency so you wouldn't hear a tone from a signal with zero offset.  You should have the Offset knob slightly to the left on 80m and 40m (LSB offset) and slightly to the right of zero for the USB bands.

The Zero Beat Knob

So with the information above in mind... Pressing the Zero Beat button defeats whatever the Offset knob is set to (effectively zeroing the offset).  When you are exactly on frequency with a signal the audio from the signal nulls (goes silent).  This null / silence is your indication that your transmitter frequency matches the other station.  

However I've found that the Null or Zero Beat is quite broad, such that you could be up to 250Hz off frequency based on where you leave the PTO in the Null. 

For my radio, on LSB bands, I press the Zero Beat button, find the null and then go past it (turning the knob to the left) and then just tweak it back into the null.  At least for my radio that works.  Maybe other Century 21s have a finer Q on the Null.  

After you have zero beat the signal you can use the Offset knob like a RIT. The range on that knob is really broad.  I think the manual said 5kHz so just a touch goes a long way unless you like to listen to CW with a ear piercing 2kHz, high pitched tone.

Here's a video demonstrating operating the rig...

TEN-TEC Century 21 -- Front Panel Controls

QSK

The Century 21 has full break-in QSK on at all times.  It is extremely clean with no discernable pops or artifacts.  One complaint I have is that the pitch and tone of the sidetone itself is fixed.  You can vary the volume through a little hole in the bottom cover to turn a thumb wheel, from very loud to just loud but you cannot change the pitch and it's a bit harsh sounding. 

The headphone jack on my particular radio is broken.  I need to open it up to resolve that before the wife uses a large heavy object on my beautiful new transceiver.

Selectivity

This video demonstrates the receiver selectivity of this old radio. 

Where is the S-Meter?

This is a bare bones transceiver with just the basics necessary for CW communication.  As far as information for the operator: Well there's an analog dial that gives you a rough indication (within 5kHz) of where you are transmitting, and an input wattage gauge for the drive and that's all.  Notably missing is a Signal Strength meter so the signal reports you send will be based on your ear, or how generous you're feeling at the time.

It's a little funny to me that I'm enjoying using this radio given it's lack of... well just about everything compared to my Elecraft KX3 whose tiny display indicates Signal Strength, Signal Relative to Zero Beat, SWR, RIT Offset, VFO A/B (down to a 10Hz range) Time, PA Temp, etc.  It just goes to show you how much modern rigs have that, when it comes down to it, isn't actually necessary for communication.

Specifications

A bit of history about TenTec QRP radios and the C21 from a 1977 magazing article...

https://archive.org/stream/73-magazine-1977-12/12_December_1977#page/n29/mode/2up

General

• Frequency Coverage: 3.5 to 4.0; 7.0 to 7.5; 14.0 to 14.5; 21.0 to 21.5; 28.0 to 28.5; 28.5 to 29.0 MHz. (Crystal not supplied for 28.5 to 29.0 MHz, but available as accessory, Model 273.) Note - Early models only included crystals for 3.5, 7, and 14 MHz bands. Crystals for 21 Mhz and 28 Mhz bands were available as optional Models numbers 271 and 272.
• VFO Frequency Stability: less than 20 Hz change per degree Fahrenheit, averaged over a 40^o change from 70^o to 110^o, after 30 minute warmup. Less than 20 Hz change from 105 to 125 VAC line voltage.
• Direct Frequency Readout: Marked in 5 kHz increments from 0 - 500 kHz, MHz markings for each band displayed.
• Tuning Rate: Approximately 17 kHz per revolution of main tuning knob.
• Power Requirements: 105 - 125 VAC, 50-60 Hz. 10 watts receive, 100 watts transmit.
• Semiconductors: 25 transistors, 26 diodes, 5 integrated circuits.
• PC Boards: 4 plug-in types, 6 integral.
• Construction: Rigid aluminum chassis and sub-panels. Aluminum case. Grey front panel, black textured vinyl cover.
• Dimensions: HWD 6.125" x 12.5" x 12"
• Weight: 15.5 lbs

Receiver

• Sensitivity: 1 uV or less for 10 dB S+N/N.
• Selectivity: Three position; 0.5, 1.0, and 2.5 kHz.
• VFO Frequency: 5.0 to 5.5 MHz. Double Direct Conversion.
• Antenna Input: 50 ohms, unbalanced.
• Audio Output: 1 watt @ 8 ohms, less than 2% harmonic distortion. Built-in speaker; PHONES jack.
• Offset Tuning: Approximately +/- 5 kHz, defeatable with ZERO BEAT switch.

Transmitter

• DC Input Power: 70 watts
• RF Output Power: 25-30 watts, typical.
• Output Impedance: 50 - 75 ohms, unbalanced.
• T/R Switching: Full break-in cw with PIN diode switch.

QSO

Sample QSO... Listen to the lovely receiver but the horrible sidetone.

Update: Here's another QSO I made a few months later into learning the Code.

And here's yet another from Straight Key Night 2017.

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Some of this old beauty's insides...

As I use the rig more I'll try to make some recordings and post them in subsequent blogs but that's all for now.

So lower your power and raise your expectations

73 / 72

Richard

AA4OO (formerly N4PBQ)

The Perception of Power

Power... or lack thereof

I had a good afternoon playing radio on 40m, 30m, 20m and 17m

I like 30m because that band seems to be more laid back and I seem to have some of the longest ragchews there.  One of the QSOs began with a fellow in CT using a K2 at 80w while I was running 5w.  

As the QSO progressed he was surprised by how well he could hear a QRP station.  This seems to be repeated often enough to me that I asked him to lower his power and see how it goes.  

He lowered his power from 80w to 50w and I gave him a signal report that didn't differ from his original.  Then he came down to 20w and I dropped him a point. Eventually he lowered his power down to 5w while I went to about 1w.  We continued to have our QSO although QSB started to make copy difficult but the main thing was that he was very surprised that he could come down to 5w and have me hear him and that he could still copy me at 1w.  We were both using wire antennas and he was about 500 miles north of me.  Solar Flux was only 107 today so it wasn't particularly stellar (pun intended) and it wasn't grey line by any means.

I think QRP operators should encourage QRO operators to try lowering their power just as an experiment.  After all we are supposed to use just enough power for communication, rather than all that we can generate.  I generally start at 5w and if a station is having difficulty or gives me a 339 I'll turn it up to my scorching 12w.

Save power, save the planet.  Maybe we can design a CW key that generates enough power to run our milliwatt rigs.

So lower your power and raise your expectations

73 es 72

Richard

N4PBQ

Telegraphers of the Civil War -- Book

Brass Pounders

I just read "Brass Pounders -- Young Telegraphers of the Civil War" by Alvin F. Harlow.

Available on Amazon  Brass-Pounders-Young-Telegraphers-The-Civil-War

It is a collection of stories I assume to be mostly true of the young men and their adventures in their service as telegraphers during the Civil War.  There's really not much in there about telegraphy in particular, more just about the gumption of those young men (boys really).   Also this was long before radio-telegraphy so it has nothing to do with amateur-radio or CW but some may find it an interesting read.

It certainly was a different time and different sensibilities regarding the independence of boys and what they can accomplish.  It's certainly no great literary work but it is an interesting read.  

It does show the growing recognition of the importance of the telegraph in war-time communications.  

Some of the telegrapher's became well known such as Jesse Bunnell who later designed an improved sideswiper key to deal with telegrapher "glass arm"

That's all for now.

So lower your power and raise your expectations

73
Richard
N4PBQ

Morse Code... is Only Mostly Dead

Morse Code is getting Old--er

As a new CW operator I find questions concerning CW-Morse Code operators and learning Morse Code interesting. In particular the AGE of CW-Morse Code operators interested me. When I completed my 100th CW QSO as a new operator I decided to gather some statistics on age of  Morse Code operator with whom I had QSOs.

I took my log and wrote a program to query QRZ database.  I used the python-hamtools library as the basis of parsing my ADIF log and performing the QRZ database lookups.  In order to query QRZ you need a subscription.  QRZ doesn't have the birth year for all operators but it had it for 58 of the original 100 CW mode contacts.

Here is the birth year summary for CW operators in my log:

Average Age: 68 

Min Age: 35 

Max Age: 99 (yes, 99 he's a ham in TX)

I am in my 50s and just learned the code. I find the average age of 68 pretty indicative that there don't seem to be a lot of young CW operators.  As CW operators die off who will replace them? 

I recognize that these statistics aren't too meaningful without knowing the average age of all licensed hams in the QRZ database. If I knew that then I could make more meaningful comparisons.

Where will new Morse Code Operators come from?

So based on the statistical age from my CW QSO logs; Morse Code doesn't seem to be considered relevant by most folks under half a century old. 

A Google Search of "Morse Code Alive" returns 286,000 hits. Conversely, a Google Search of "Morse Code Dead" returns 733,000 hits. 

So statistically, Morse Code is considered mostly dead... Yes I like this movie...


My kids consider me nuts for taking the time to learn and use Morse Code. I haven't been able to convince them of its relevance or even the relevance of ham radio. They point out to me that they can communicate with all their friends just fine via Google Chat or Texting. Even my lovely wife, who is a licensed Ham, doesn't see the point in learning Morse Code.

So... my question is; can we bring relevance back to Morse Code to a younger generation?  Yes it's fun, yes it's a challenge, yes it uses the least amount of radio spectrum for communication, yes it allows the furthest communication on the least amount of power... 

Will Morse Code die with the generation(s) that use it today?

And on that somber question, I'll await some comments (hopefully constructive).

So lower your power and raise your expectations

73
Richard
N4PBQ

UPDATE March 2017:
I found this graph from my Youtube viewer demographics interesting...

100+ Morse Code QSOs as a new CW operator

Passing my 100+ CW mode QSO goal

Last weekend my 100th CW contact was with Terry K8EHE

It took me about six weeks from my first on-air QSO to reach this goal.  I created a map of my world wide QSOs.  Some stations are represented more than once on the map because I had contacts with them on subsequent days.

For some reason stations with a slash in the call failed to generate locations on the map due to a bug in the program I'm using to generate the KML. So some of the stations (at least a few of the DX stations) aren't displayed.

World Wide QSO map (excluding stations with slash in their call)

This map shows the US contacts so far...

Operators in the Midwest must not answer my CQ

Encourage new CW operators

Last night I had the opportunity to be the first CW contact for Larren KE0CGB, so it's good to hear other new CW operators coming on the air.  I made sure to QRS to a speed he could comfortably copy. 


That's all for now

So Lower your power and raise your expectations

73
Richard
N4PBQ

Suburb Antenna

The "New Carolina Windom" in North Carolina

My location is in a typical new-construction, American suburb and doesn't allow for ideal antenna solutions.  My subdivision was built on a field previously growing tobacco, beans and cotton, depending on the crop rotation.  So when the house was built (2002) the tallest point on the property was the peak of the roof.

Arial view of QTH as built

There were a couple of sticks in the front yard about 8ft tall that the builder called trees.  I wasn't licensed as a Ham yet so I wasn't in the mindset where I'd hang an antenna. 

By the time I was licensed as a Ham some things had grown up around us but they were mostly other houses.  The trees just hadn't grown much in 5 years.

QTH at the time I was licensed

I started off with a couple of attic antennas.  I first had a 20m Carolina Windom and a Tarheel Screwdriver in the attic.  The Little Tarheel would tune 40 but my counterpoise system was poor so it didn't perform well.  The Little Tarheel screwdriver antenna actually performed better on my vehicle working European stations on phone band while mobile than in the attic.  The 20m Carolina Windom in the attic made contacts but electrical noise from the proximity of wiring was pretty bad.  I tried a number of other antennas in the attic and in general none worked very well.  I needed to get an antenna outside. 

I don't have strict covenants but towers and push up poles are prohibited so I need to attach a wire to the house in some way. The tallest point on my house that was semi-accessible was the peak of the roof on the Southern facing side.  I had a window in the third story attic just under that peak.  At the time I didn't have an antenna tuner so I read about multi-band wire antennas that supposedly didn't require tuning for multiple bands.  A fan dipole could have been a good choice but I had to have the antenna in an inverted V and there was nothing of height in the rear to keep the lower elements of the fan far enough above ground.

I settled on the "New Carolina Windom" 

Schematic for New Carolina Windom

This antenna had a number of advantages for me.  It is multi-band and theoretically doesn't require tuning for 40m, 30m, 20m and 15m.  I ordered a 4:1 balun and a line isolator, wire, rope and coax and got to work.  Since I my antenna had to be inverted originally it turned out to not tune as well as I'd like.  The antenna tuned under 3:1 on all the bands and under 2:1 on 40m in the phone segment.  I used the antenna for a couple of years back when I was doing QRO phone and digital modes until a mishap brought it down and it laid under the bushes up next to the house for 6 years.

Now where did I leave that antenna?

When I became interested in QRP and CW again a few weeks ago I had a portable end-fed long wire but nothing for the home QTH.  I remembered the Windom buried under the bushes.  In the six intervening years my trees had gained a bit more height so it was not quite as inverted as it used to be.  Strangely now that the long segment (41ft) is more or less flat-top and the short segment is inverted it tunes 20m under 2:1 and 40m is now 3:1.  30m SWR is now about 6:1 but I have a tuner to handle that and it's been quite effective on 30m QRP.  Actually there is one more change. The original vertical coax segment of 10ft was unusable after all those years under the bushes and I used the only other ready made, short coax segment that I still had amongst my cache of antenna supplies. That vertical radiator segment is now 12ft rather than 10ft so that may be the reason for the tuning difference.  This is certainly not a well designed experiment.  

I'm confident that if I took the time to trim the wires to proper length and get the vertical radiator segment the correct length it would tune under 2:1 in all the bands it's designed to operate on but for now I prefer spending my time making contacts.  When it cools down here in NC I'll do some more antenna work.

My point is that this antenna (even with the misconfiguration) seems to work fairly well on 40m, 30m and 20m  I've never made any contacts on 15m with it but I don't hear much on that band.  

It outperforms my 40m doublet at the same height (~25ft) by 2S-Points from some limited tests and is definitely quieter on receive.  I've worked Chile, Spain and Eastern Europe with QRP CW.  The wires are not in-line as there is about a 15deg angle toward the South.  I have worked Utah in the US from NC but that's as far West as I've gotten on CW.  I tend to not stay up late enough to work the gray line propagation heading in that direction.  The ends of the antenna head West and East so that null to the West may be an issue.

I understand that anecdotal reports aren't terribly useful as some may be able to report that they've worked Madagascar using a spoon with one watt but this antenna works for me. 

Here is a view of the antenna as it lives today.  The 4:1 balun hangs from a dacron rope attached to the peak of my roof far enough down so that I can retrieve it back in the 3rd story window for maintenance and detach it (that is the extra rope you see heading to the window).  From there the vertical radiator goes to a choke.  I didn't want there to be stress on the coax of that vertical radiator due to the weight of the choke so I have another dacron rope running down that coax and attaching the choke to the upper balun as stress relief for the coax.  The long segment of the New Carolina Windom heads off to the now 25 ft tall tree in the from yard and the rear element slopes down to a bean pole in the garden behind the house.  From the front of the house the antenna is not visible and my next door neighbor who can see it doesn't seem to mind.

View of the balun and choke at the end of the vertical segment

So if you're looking for a reasonable performing multi band antenna and you need one segment shorter than the other based on your QTH restrictions I can recommend the New Carolina Windom.

--- UPDATE Nov 1, 2015 ---

Since this review I replaced the 40m New Carolina Windom with a standard 80m Windom (OCF Dipole) at the same position.  It is resonant (requires no tuning) on 80m, 40m, 20m and 10m.

80m Windom 4:1 Current Balun

Long side of Windom (89') attached to fiberglass pole @12' agl

So the 40m Windom is no-more.

That's all for now

So lower your power and raise your expectations

73

Richard

N4PBQ

QRP Antennas

Lower your Power and Crank-Up your Tower

QRP means low power but not limited antennas

This antenna site is used by a group of local QRP operators (part of the KnightLites group) to work DX (for example working Hawaii on 160m with less than a watt).  In addition to a beam, the 72ft crank up tower normally supports a number of wire antennas that go to the surrounding ring of trees including a half wave delta loop for 160m.

Excalibur

The site is out in the woods, located away from urban RF interference and is battery powered via a solar array.  It is an ideal location for pulling low powered QRP signals out of the noise.

A lightning strike a few years back badly damaged the shack and it was decided to tear it down and restore the site.  The shack was de-constructed last year but the debris was still on site.  We spent the morning carting away 3 pickup truck loads from the de-constructed shack and cleaning up the site, making it ready for use again.  The tower appears to be sound but Paul plans to have it checked out professionally before taking it back up to full height.

Dick assuming the DOT worker pose

Our cleanup disturbed the homes of some wildlife

Taking debris to the recycling center

Richard and Paul at the base of Excalibur

Recovered antenna elements ready for reassembly 

I'm looking forward to the opportunity to connect my QRP radio to some serious antennas at the Fall QSO party.

That's all for now.

So lower your power and raise your expectations

Richard
N4PBQ