This is a view of the micro-shack where I have my own little world..... It must be a little
world because |
I can contact most of it from here.
I have two High Frequency Radio Transceivers, a very old (but faithful) YAESU 747 and an ICOM IC-
746 which is virtually a "shack in a box". There are two antenna tuners. (I don't know why we call them antenna tuners they are aerial tuners, an antenna is what sticks out of an insects head.) The one directly above my head is the NEVADA TM 1,000 with balun fitted internally. The black box on top of the Nevada (under the book) is the SGC Smartuner model SG-230. The Icom 746 has an automatic tuner fitted and it is pretty good, however I discovered that it is possible to connect either the TM 1,000 or the SG-230 in series
with it for really fine tuning. You will also notice what appears to be a ZETAGI HP 1000 Transmatch
well it is not a Zetagi Transmatch, it was, but I ripped the innards out and replaced them with a circuit of
my own design.
Below the Transmatch you will notice a long squat blue rectangle this is my version of the Tona Tuner
which enables me to accurately zero in on packet stations very quickly and accurately. The 747 is below
that and below the 747 is my faithful SE Automatic Counter / Timer Model SM 205 this was a quality
instrument in its day, as it still works perfectly it has a place in the shack.
To the right of the SM-205 you will see two switch boxes, these enable me to change over rapidly from
one computer to another. The switches also enable me to switch between the Internet and Fax, to the
Packet Modem, then through the Camera Interface to position four which is the Weather Station.
The black box under the Watson PSU is the IC-746 and to the right of that is the monitor for my small
computer. There are two modest computers in the shack the main computer was built by Mossbank and
the small computer is a special design also built by Mossbank. Neither computer are large machines or
even fast they were built for reliability and endless number crunching as required by SETI (Search for
Extraterrestrial Intelligence) which is what they do when I am not using them. You may ask why am I searching for extraterrestrial intelligence? The answer is very simple .... There is no evidence of it down here on Earth !!!
The strange dial sticking out of the right side of my head is a barometer for measuring air pressure, not
inside my head but atmospheric pressure. The other strange object sitting on top of the switch boxes will be immediately recognisable by a few strange people who have difficulty with one of their trouser legs.
I retired from my profession during 1995 and began building kites to further my hobby of Amateur
Radio, fortunately or unfortunately depending on your point of view the kite building began to take over
my life and I inadvertently found myself working full time again. I now only build kites when I feel like it, It's
only a hobby now and that's the way I intend it to stay.
There are three other VHF/UHF rigs, An Alinco DJ-G5 used for back packing and possible emergencies.. An Alinco DR-150E used in the car and a very simple Yaesu FT-23R which is exclusively used in the kitchen to monitor my favourite frequency S22, 145,550 Mhz. I am also a compulsive designer and builder, the debris in the shed is witness to that.
THE TM-1000 AERIAL TUNING UNIT REVISITED
I lost the circuit diagram my TM-1000 some time ago and opened the case to try and figure out the circuitry and the diagram below is my best attempt. ...
The TM1000 antenna tuner has been round for many years, it is a very old design which has stood the test of time. It is not often that a really good piece of engineering comes along and does exactly what it says on the tin. The tin or chassis of this unit is a substantial piece of steel finished with a crackle paint job. All electrical parts are big and strong well up to the job. It will take 500 Watts all day long and easily handle 1000 Watts for short periods of time. It will also work very well as a QRP tuner as the internal losses are very low.
There are two versions one with and one without an internal balun. With the balun installed it is simply a matter of moving a jumper bar (link) to the output you need either balanced or unbalanced. The ferrite toroid transformer has a very substantial core with reasonably stout
Enamelled Copper Wire (ECW) which looks to be about 1mm diameter.
The soldered joints are all very well made and should not fail under heavy operating conditions with wide temperature fluctuations. Any instrument which is constructed from metal will eventually tarnish and the bearings will eventually dry out. Where dissimilar metals come into contact there may be a small amount electrolysis this is not a problem at high power but will become apparent at very low power. On an old unit it is well worth checking that these connections are in good condition and a drop of oil on the bearings.
Do not be fooled into thinking that this is a simple piece of equipment the schematic circuit diagram would lead you to believe. Mechanically it is a work of sheer genius and must have taken years to develop. Circuits like this have been round since Marconi’s time and the mechanics have evolved over this time. This is not a piece of junk it is the Rolls Royce or Quad of the species. If you can pick one up grab it at any price and get to work.
The balun board is simplicity itself, switching between balanced and unbalanced is by moving the position of the jumper bar see # 01. Dust is another curse a soft brush is the best way to remove it from between the capacitor plates. The remainder can be removed with a vacuum cleaner.
Hopefully anyone finding this blog will get in contact and swap ideas and perfect the circuit where it is not correct.
The front panel of the TM1000. To refine the tuning I added two large 360° calibrated escutcheon plates which helps when noting down the settings for a particular frequency.
The rear panel of the TM1000 is relatively uncluttered. If you look carefully between the balun output connectors you will see faint writing.
This is the name of the chap (A Radio Amateur ) who built this unit together with his call sign and home address.
I looked him up on QRZ and he apparently still lives at that location.
The inner workings of the TM100 .... what a testament to his craftsmanship.
Don't worry about the two pigtails touching one another, there is at least two inches separating them. The balun winding appears to be an auto transformer type but I can't be sure without first disassembling it. If you can give enlightenment I will print it here.
This page has provoked some questions which need answers which I am not qualified to give. However in the interests of the Amateur Radio fraternity I think one solution is to publish the questions here in the hope that soloutions may be found.
I just picked up a TM1000 ATU minus the toroid. Looking at your web page is that a 9:1 balun in there.
I want to put it back to it’s original condition and need any info I can get.
I think it's a 4:1 balun with roughly 24 turns on a large ferrite ring. (TOROID)
A large ring can be made using two stuck together. It is preferable to use the
biggest toroid that you can find as small ones tend to get hot.
I came across your web page regarding the above ATU, I acquired one recently, unfortunately, not in very good condition. It was damaged in transit, the bottom corner of the case is badly dented so I have striped the unit to repair the case and get it re-sprayed. I wonder if you could help with the following queries.
1) Could you supply a copy of the original manual, I will gladly reimburse any cost?.
2) Do you know the value of the small and large capacitor capacitance?
3) The turns counter dial on the roller- coaster is damaged beyond repair, do you know where I might obtain a replacement. Nevada were of no help they don’t know anything about this unit because of its’ age?
4) Have you had any problems with high resistance on the roller-coaster bearings, unless I am mistaken electrical contact is taken through the ball bearings of the end bearings. I once built an ATU using the same roller-coaster and I had to fabricate a different method of connection. The resistance through the bearings was several ohms, not good at high powers.
Sorry to bother you, I got your email address from QRZ.com.
Hope you can help.
I purchased the unit from Nevada over thirty years ago and the circuit
diagram came with it, unfortunately over the years involving change of
address it somehow got lost. When I say lost it is probably stored
safely in one of my back issues of Practical Wireless ..... It consisted
of a photocopied A4 folded. That's Q1 sorted.
Re Q2 I believe they are 500 pF's
Re Q3 http://www.minute-man.com/acatalog/Vernier_Dial_for_Potentiometers.html
there is an image of the "Vernier Turns Counter" at that address.
use ....Vernier turns counter on Gooooogle.
Re 4 High resistance on bearings. ........
Depends on the wiring of your unit and its use.
If the unit is used frequently resistance is only measurable
using the four point method and should be less than .001
1/000th Ohm. or a small fraction of a dB.
Do not remove the bearings add a rotating compression contact
QRZ has a lot to answer for.
Good luck with the refurbish.
It’s me again! Just an update and some queries. First of all I’ve ended up getting the ATU free of charge!! The guy sent me my money back because of the damage in transit, although that was clearly not his fault. He was claiming on the insurance so he must have been pretty sure the claim would be upheld. I told him to hang on until he received a cheque from the insurance company but his cheque with a full refund including the postage arrived next day. I must say it restores your faith in human nature. I managed to straighten out the case and have now had it stove enamelled. It was a funny sort of browny grey colour I asked for it to be painted dark grey, it is now a funny sort of bluey grey colour. Still, it now looks like new and you have to look very hard to find any trace of the previous damage.
Finding a suitable turns counter is going to be a problem. I packed the damaged one with grease and it is now a lot smoother so I think it will be useable in the short term.
The ball bearing caged bearings on the rollercoaster, I decided I would clean them in a small ultrasonic cleaning tank, the resistance through the bearing is now worse!! but I am not connecting to earth and the other end I have a copper disc attached (by the convenient M6 thread in the end of the shaft) with a sprung silver contact bearing on it so that should overcome the “high” resistance.
Now the query, the large capacitor, looking at the photograph of your unit, is connected one end to one of the stators and the other connection to the other stator. There is no direct connection to the rotor, the two stators are insulated from each other and are coupled by the rotor, am I correct in this?
Sorry to bother you, hope you are still working the world. I understand 10m has been pretty lively recently but I can’t work that band at the moment, hopefully the ATU will assist in that SOON!!
The circuit may be as in the above diagram the lower earthy end of the inductor
may not be connected as this will avoid circulating RF currents. We badly need to get this diagram perfected.
Amateur Radio is a "Society of Friends" we all help each other.
I am doing a paint spray job at the moment on a model aircraft,
I decided to use VW Lahasa Metallic which is a dark charcoal.
I rebuilt my 25 Amp Power supply and was pleased with the
result of using that paint.
Anyway.... back to the subject....
There is the potential for circulating currents as shown on the top sketch.
Without the lower inductor connection the unit will still function.
Regarding the high resistance on the clean bearings ....
Nyogel or Servisol if they are still available should help, ..
however both should be used sparingly.
Try comparing the circuitry in your machine with the diagrams
below I could have drawn it incorrectly, ... If so I will modify
the diagram on the web page. Incidentally that page is very much
out of date as the shack was abandoned after the lightening strike.
Stevie B wrote:
I got a Nevada TM1000 Atu with the balun removed and would like to find out where you got the 360 degree calibrated plates for it. Also looking for circuit diagram and advice on to service it as it squeaks like a mouse when tuning the coil. Do I just clean the wheel slide and use a light oil or Vaseline ? Many thanks for your help.
The calibrated plates came from a Military machine of some description.
I say that with tongue in cheek as I am not sure.
Many years ago there was an electronics scrap merchant who specialised
in purchasing / flogging old military equipment .... The infamous “TV McDonald” who
let me root through his stock and I found the plates in their original grease
proof paper, purchased them from him for 20P, the pair.
My vernier also squeaks and it is the slow motion drive I believe is the cause.
The drive unit is susceptible to this ..... Years ago Maplin sold similar vernier
slow motion drive units and they all squeak eventually. Don’t oil
the vernier as it uses a friction clutch arrangement. What I have noticed is
that the squeak diminished if used frequently. Clock oil is the only oil
to use on the other parts as it does not evaporate and become sticky.
Google the following:-
vernier slow motion
Thanks for your e-mail and answers to my queries
I just wondered what tuning procedure if any, was recommended in the original instructions.I have copies of two articles “Getting the Most Out of Your T-Network Antenna Tuner” QST January 1995 and “A General Purpose Antenna Tuning Unit” RadCom January 1987 both very interesting. More than willing to send you copies of these copies if you are interested. With regard to the circuit diagram you traced I am sure I have read some where not to earth the bottom end of the coil because as the earthed slider moves up the windings it effectively creates a shorted turn which degrades the Q of the coil. When I built the ATU some years ago now I didn’t earth the bottom of the coil and it seemed to work OK, but I never did any comparative performance measurements. Incidentally, I overcame the high resistance of the bearing in exactly the way you suggested. I think one of the bearings is OK resistance wise on the Nevada ATU so I will use that on the “business” end of the coil.
I have looked on ebay for turns counters, they are very expensive (around £50) and they won’t fit, I’m talking about the ones with the rectangular escutchion face.Looking at the plastic gear teeth on the Nevada turns counter a bit of judicious use of a needle file might just do the trick.
Anyway, thanks again, I will try not to bother you any further on this subject
When using a tuner such as the TM1000 there is an infinite number of settings and there is no point in relying on memory, notes must be made. Eventually you will have so many notes that you will need to use a computer spreadsheet. Excel is as good as any but there are many other spreadsheets out there and available for free. The spreadsheet enables you to sort out the settings into order of frequency which speeds up searching through lists.
I had a search on the internet and I found this US Patent which looks exactly like the TM1000 circuit schematic.
I have re-drawn it using the UK parts I understand, the only difference is that the twin gang Tune capacitor is not split by the rollercoaster inductor, only the lower half of the tune capacitor goes to earth.
We still have the potential for circulating RF on the earthy side of the inductor.
The printed circuit board has now been made more obvious.
We may be getting closer to the original circuirt schematic which would be a good thing as this machine can tune a barn door.
Note the Nevada TM1000 predates this US patent by several decades.
Data de publicação 29 maio 2007 The patent reads:-
In a T network tuner, a variable shunt capacitor is provided between the signal input and ground that is ganged to the variable input matching capacitor. The operation is mechanically arranged such that, as one decreases the capacitance of the variable input matching capacitor, one increases the capacitance of the shunt capacitor to assist in high frequency matching, both to increase the maximum matchable load resistance and to decrease the minimum matchable load resistance. The variable shunt capacitor therefore assists at the high frequency ranges to bring the antenna impedances down to the transmitter output impedance, thus to establish an extended matching range tuner capable working between 160 and 10 meters.
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Two simple Lightening Detector Circuits.
My home was struck by lightning on 8th June 2003 and cost my insurance company several thousand
to replace my computers and radio equipment. Lightning is a terrible force of nature and a warning of its approach
will give you time to disconnect everything, hopefully in time before a strike hits. I have also recently taken up hill walking which represents another chance of possibly being struck so I decided to do something about it. The circuit I am now using is my version of http://www.techlib.com/electronics/lightning.html which I have updated to more readily available transistors 2N3906 and 2N3904. All I need from this unit is for a buzzer to sound each time there is a discharge and to turn itself off immediately to await the next discharge. The original SCR version would not reliably turn off when using a DC supply but this more complicated version is be very economical powered by two AA cells, or with the addition of a 78L05 a miniature 12v lighter battery.
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