Nautel 60 KW Mediumwave TX

Discussion in 'Technical' started by NewWave, Jul 1, 2017.

  1. NewWave

    NewWave Member

    Hello guys, All fine on the other side off the lake?
    I'm just bought an almost never used Nautel 60 KW Solid State Medium Wave TX.
    It was 20 years used as backup for the main 600 KW TX here in Holland,
    and was used only 4 month during al these years, All parts looking like new.
    This TX is build up by 4 X 12 plugins in 4 cabinets, each 1.25 KW carrier. and contains two 50 KVA Power supplies.
    The whole PA stage is running by 72 Volts on the PWM section on every PA plugin has its own own PWM stage.

    Monday I have to load up this almost new TX and rent a 10 tons truck for it.

  2. W5HRO

    W5HRO Administrator

    Way cool!

    So it's class E with a pulse width modulator?
  3. NewWave

    NewWave Member

    It's Bridged D, two stages in parallel 400+Watts X 3 in each rack gives 1.25 KW carrier. Each Amp has his own PWM modulator stage plus driver. needs an TTL PWM signaal only. ( 70 KHz.)
    HF drive needs 20 Volts peak peak on each plugin..

    Below the truck I have rent for monday

    IMG-20170628-WA0012.jpeg 20170701_133009.jpg
  4. NewWave

    NewWave Member

    Nautel using only Bridged D in MW TX..
    4 plugins are symmetrical combined ...( picture below).. output combined gives 5 KW on 50 Ohms... 12 output in total going parallel in one Band Pas section and 50 Ohm loading cabinet.
    I bought this TX because he is like new..
    comes from the Dutch Broadcast society... I Was that time on the right place and at the right time... It's very special to get some like this..

    20170701_182008.jpg 20170626_134937[1].jpg
    20170409_113442.jpg 20170409_113747.jpg
  5. NewWave

    NewWave Member

    Like to keep one or two 15 KW units. in the USA and other coutrys there are much stations interested in plugins...

    20170409_113813.jpg 20170409_113719.jpg 20170409_113450.jpg
  6. NewWave

    NewWave Member

    The reason for bridges D concept is, no spikes in the output sections and no blocking capacitor changes in the Drain sections by frequency change, like you have in E a concept.. In almost every country on the globe you will find TX from this brand. The J 1000 (1KW) from Nautel is a popular backup TX, also in the USA..

    Everything looks new, even dust is not visible.

  7. W6MQI

    W6MQI Member

    So what are you going to use this for Hans? Planning on putting a shortwave broadcast station on the air sometime soon? Geez 60kw what's the power requirement to run this baby 3 phase 440v? Looks really cool anyway.

  8. NewWave

    NewWave Member

    Hi Dave, I've been working for two days now to dismantle and load in the truck. It is an MW transmitter and may be up to 1.85 MHz. There is a big combiner unit in it, and it is custom made for 747 KHz. Without variable capacitors, so it will be a problem to handle this all on different frequencies. but all 48 plugins 1.25 KW stages are broadband.
    All runs on 3 X 400 Volt by two 50 KVA step up transformers 54 Volt A.C. (72 DC).

    here some pic's from the 747 KHz. combiner..
    20170703_135605.jpg 20170703_135754.jpg
  9. NewWave

    NewWave Member

    little problem to take pictures on the right place by phone on the site..

    20170703_135631.jpg 20170703_135714.jpg 20170703_135547.jpg
  10. NewWave

    NewWave Member

    Already build up one rack with 12 PA's.. 15 KW. 4 PA's connect to one Combiner and go's out by 50 Ohm.
    Each PA has one blower and runs by 24 VDC 0.25 Amp.
    20170704_161745.jpg 20170704_185015.jpg
    4 Pa's connected to the combiner, in the middle 50 Ohm broadband 530 - 1700 Kc output. (combiner output is shielded by aluminum cover)
    This TX is special made for the 747 KHz. (one of our National Broadcast frequencies)
    Only the Big 60 KW combiner is tuned to 747 KHz. (by fixed coils / capacitors) , all other stages are broadband.
    After loading the whole TX in my 18 tons truck, i receive a present from the director....:icon_angel:
    20170704_182108.jpg 20170704_113104.jpg
    a very nice water cooled 25 KW dummy load... For free !!
    60 Hz..... 1.8 GHz. !! Connector is 3 Inch.. :eek:
  11. W5HRO

    W5HRO Administrator

    I think what he was asking Hans is if you are going to try it on the ham bands :mrgreen:

    Would be fun to try 60kW on 160 and/or 75-meters :icon_shh:
  12. NewWave

    NewWave Member

    Hi Brian.. (And all other viewers)

    All 1.25 KW pa plugins has 3 x 8 IRF 140 for 3 x 400+ Watts per plugin ( Three stages inside in each plugin) , by 30 ns rise time it must possible to run this on 1.85 and 3.5 Mhz. maybe by reduced Power... 800 - 1000 Watts per block.
    Wall Power is no problem, i can take 3 X 100 Amps / 400 Volts.
    I will take inside pic's from one Power plugin..

    But... I'm wondering about the Power transformer, this is not isolated, there are three taps for 54 Volts AC on the Primary 400 Volts side !! Followed by three neg. and three pos. 500 Amp rectifiers... That's All !!
    I've never seen this before... Canadian way to build it cheaper ??

    IRF 140 Datasheet.PNG Trafo nautel.PNG

    TX price was 160.000 Euro (early 90's) including three weeks for build it up at location.
  13. NewWave

    NewWave Member

    1.PNG 2.PNG
    1.25 KW plugin...
    4.PNG 5.PNG
    (Left pic) Rear side, below the symmetrical output, at the top,
    the 72 Volt DC, RF drive, PWM drive, low voltage plug.
    One coil for tuned input section to eliminate harmonics from drive stage.
    One small Blower is needed for cooling this three PA's, HF efficiency PA's is around 85 - 87%

    (Right pic) bottom view, by three output transformers. (in series by 4 x mix 87 cores) 2:6 and the input rail.
    On the left side, the 40 Amp. metering shunt.
    The PA section is Positive Grounded, all other inputs Neg. grounded.
    Also three Big Capacitors each 18.000 uF / 100 Volt in parallel on the top of the modulator (72 Volt side)

    One PA stage: Bottom, PWM filter (70 KHz.).. Print board, by two input transformers. (3:2) mix 43 cores.
  14. NewWave

    NewWave Member

    8 X IRF 140 for the HF Stage, and two IRF 130 for the PWM modulation (left)
    30 Fets in one PA plugin. in total 360 Fets in one cabinet, 4 cabinets contains 1440 Fets. for 60 KW output (Carrier)
    every plugin has three modulators, 36 in each cabinet, total 144 modulators in 4 cabinets.
    72 Volts on the modulator top, 30 - 33 Volts gives the modulator out for carrier without modulation.
    (PWM Duty Cycle 40-60)
    Modulation is 100 % and 140% by using neg. peak limiter.
    All plugins looking like new, this TX was located in a temperature / humidity controlled room.

  15. NewWave

    NewWave Member

    Fun by areal radiation to Brian ?:icon_crazy:
    At least 50 / 100 meter 7/8 or 1-5/8 Coax line between antenna and TX I think.. 8)
  16. W6MQI

    W6MQI Member

    With that kind of power Han's will be arm chair copy here in the states heck we might even hear him here in Kalifornia he'll burn right through that 160 meter aurora donut that stops most euro stations from making here to Kalifornia. Han's will make his own propagation with 60kw if doesn't blow himself up first.
  17. NewWave

    NewWave Member

    Propagation is for QRP Power levels like Brian's 1000 Watt important only ..LOL..;)
    Like to know what kind of reactions there comes by amateur stations here in Europe, if they hear a signal, and realized afterwards, there was no antenna connected :eek:
    But.. The exciter is running to 1700 Kc only, :surprised: so i have to put something else on it. 8)

    Have to build an variable final combiner for one one cabinet first, (three 50 Ohms combiners comes parallel out). 50 Ohms / 3 = 16+ Ohms to 50 Ohms out, in two steps i think.

    Like to build up, one cabinet first, there is no more room here... So if there is a amateur who has a big boat and a 200 KVA generator on board... Please let me know..;)
  18. W5HRO

    W5HRO Administrator

    Do you have room for a curtain antenna? :razz:

  19. NewWave

    NewWave Member

    Nice work Brian...:icon_thumbup:
    4 x 4 dipole for... 10 - 20 MHz. ?
    Including reflector i see... very nice, what is the gain from this antenna?
    I use an antenna with one or two DB Gain... All other gain comes from the TX...:icon_angel:

    Here in Holland we use for UHF 470 - 860 MHz. Television reception the same idea.
    10 - 12 DB Gain..

    Raster antenne, chanel 21 - 68 ... 470 - 860 MHz..PNG
    Nothing is cleaned.. Looks like....:icon_thumbup:
    Left side the connector terminal, three Teflon coax go's to the HF input, other three for the PWM input.
    And three wires for the 72 Volt input..
    On the top the tuned input coil, 4 taps for the AM broadcast band..
  20. NewWave

    NewWave Member

    1.85 MHz. Load.PNG 1.85 MHz..PNG
    Something like this Brian ?
  21. W5HRO

    W5HRO Administrator

    Curtains have been around forever. Years back I use to listen to Radio Netherlands a lot because they had one of the strongest signals here into the U.S. They used an HRS curtain design, or at least they did before shutting down in 2012.


    "Curtain arrays were originally developed during the 1920s and 1930s when there was a lot of experimentation with long distance shortwave broadcasting. The underlying concept was to achieve improvements in gain and/or directionality over the simple dipole antenna.

    In the early 1920s, Guglielmo Marconi, pioneer of radio, commissioned his assistant Charles Samuel Franklin to carry out a large scale study into the transmission characteristics of short wavelength waves and to determine their suitability for long distance transmissions. Franklin invented the first curtain array aerial system in 1924, known as the 'Franklin' or 'English' system.[2][3]

    Other early curtain arrays included the Bruce array patented by Edmond Bruce in 1927,[4] and the Sterba curtain, patented by Ernest J. Sterba in 1929.[5] The Bruce array produces a vertically-polarised signal; Sterba arrays (and the later HRS antennas) produce a horizontally-polarised signal.

    The Sterba array was used by Bell Labs and others during the 1930s and 1940s. The Sterba curtain is however a narrowband design and is only steerable by mechanical means. However, as far back as the mid-1930s, Radio Netherlands was using a rotatable HRS antenna for global coverage. Since the 1950s the HRS design has become more or less the standard for long distance high power shortwave broadcasting (> 1000 km).

    Curtain arrays were used in some of the first radar systems, such as Britain's Chain Home network. During the Cold War, large curtain arrays were used by the Voice of America, Radio Free Europe, and Radio Liberty, and analogous Western European organizations, to beam propaganda broadcasts into communist countries, which censored Western media."
  22. NewWave

    NewWave Member

    We have in the 60 - 80's the same four section curtain antenna for 174 - 216 MHz. Band 3 Television reception. A large antenna system on the roof !! a small Powered German TV station, my dad receive it, sometimes with much snow on channel 9 and and was located in "Langenberg" Germany. The VHF Pre amp ECC 84 in TV receivers was not the best pre amp. but.... there was nothing 1960..:icon_problem: Now i have the same Philips TV receivers from the 50's and 60's, complete restored in my collection. And not only the outside is restored.

    Bestand_001 (1).jpeg 20151220_142240.jpg
    Right the picture in close up. video signal over the 5 MHz on the picture tube's Cathode.

    The Pal video system, 625 Lines, was the best system in Europe, AM video, FM sound carrier. (5.5. MHz)
    1952 Philips... The same like my dad's one !!
    Bestand_006 (1).jpeg Bestand_005 (2).jpeg
    1951 Philips B/W receiver. picture tube is like new , Full emission!!
    Chassis complete rebuild.. all tubes new..

    About the TX....

    I would like to build up a half TX for experiments, have 4 combiners each 5 KW for broadcast on different / amateur freq. (20 KW carrier) the other half with the fixed combiner on 747 KHz. I would like to collect it in original condition.
    So i have to connect a second exciter and a variable 50 Ohm Combiner / Pa section. Power supply and other power capacitors / coils, i have in stock..
  23. NewWave

    NewWave Member

    RNW is unfortunately HISORY !! To much costs... They had a very nice location, curtain antennas to all directions, and Powerfully by (water cooled) tubes in the final..

    But Brian... Maybe there comes a New Wave over the US....8)
  24. W5HRO

    W5HRO Administrator

    That's one of the side effects of the new modern Internet technology, it's slowly putting all of the old and faithful AM BC stations out of business and they keep going off of the air. Sorta like Amazon has been killing the big retail chains.

    RNW was one of my most favorite BC stations to listen too. When they pointed their HRS array to the U.S. and broadcasted in English they came in like gangbusters for hours and hours for many decades. When I got back into AM around the mid 1980's with the vintage equipment again I listened to them, another BC station in Germany, and then Radio Moscow before the Soviet Union collapsed. By the time I acquired all of the National receivers I had 3 of them on 24/7. I left the HRO-50 with the AA coil on 10-meter AM, the NC-183D on Radio Netherlands, and the HRO-60 on 75-meter AM.

  25. NewWave

    NewWave Member

    Radio Netherlands World Broadcasting, was located below sea level, on a dry-laid sea, the groundwater level is very high, for Hf use extremely well.

    In the 60's -70's-80's there were several radio ships for the coast of the Netherlands. Radio Veronica was the first. Radio Nordsea international was the second, this boat was big and had SW 49 mtr. (10 kw), FM (5kw), MW (50 kw) on board. Then came the last, Radio Mi Amigo, (Harris 10kw), where I was a transmitter technician, which ended in early 1981.
    All these ships were 12 miles off the coast, in international waters..
    RNW 5.PNG
    Radio Veronica on 192 meters, later they moved to the 538 meter. 2 Continental 10 KW TX on board.
    When you look at the USA Continental site, you will see posters of this boat. This factory was very proud because their Transmitters were on board. Radio Veronica was Very .. Very popular in the 60's and 70's.!!

    Many programs were on tape, only every hour news came live from the boat. In summer, the programs came live from the boat as well.
    Radio Veronica was so popular that even a German radio factory indicated this station on the dial !!
    The Dutch Philips was forbidden to do this, by a hypocrite Dutch government.. Unbelievable !!

    RNW 7.PNG
    The Mebo 2, from RNI international.. MW antenna is over 70 meters high..

    People always talk about "pirate ships" but outside the border in international waters everyone is free ..