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Thread: ALC cable to linear?

  1. #1

    Default ALC cable to linear?

    I want to upgrade to a linear amp for a little more punch. My transceiver is an old Yaesu FT-847 which has an STBY out jack to connect 4 different linear amps (HF, 6m, 2m & 70cm amps) It also has a ALC jack out, but the manual says I need a Si diode in-line in the positive line of the RCA cable at the amp end, but it does not specify the value of the diode needed. Does anyone know what value Si diode I should use? I have a 1000v/10A diode. Will that work?

    My second question has to do with an email from Ameritron. They said I do not need to use a ALC cable at all, because my FT847 only puts out 100 watts; just use my STBY cable to connect to their ARB704 interface. Is this wise? Should I use an ALC connection cable between my transceiver and a linear or not?

  2. #2

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    Quote Originally Posted by MitchellB View Post
    I want to upgrade to a linear amp for a little more punch. My transceiver is an old Yaesu FT-847 which has an STBY out jack to connect 4 different linear amps (HF, 6m, 2m & 70cm amps) It also has a ALC jack out, but the manual says I need a Si diode in-line in the positive line of the RCA cable at the amp end, but it does not specify the value of the diode needed. Does anyone know what value Si diode I should use? I have a 1000v/10A diode. Will that work?

    My second question has to do with an email from Ameritron. They said I do not need to use a ALC cable at all, because my FT847 only puts out 100 watts; just use my STBY cable to connect to their ARB704 interface. Is this wise? Should I use an ALC connection cable between my transceiver and a linear or not?
    Hello Michelle,

    The one question I have is, Is the RF Linear Amplifier Tube or Solid State (Transistors)? Generally all RF Linear Amplifiers produce the Negative Voltage that feeds back into the FT-847 transceiver. After studying the Operators Manual I see that RCA Cable where they inserted the Diode, you'll need to build one, apparently YAESU Parts no longer stocks the cable. I believe your 1000VDC at 10 Amps is slightly an overkill. I would use a 1N4004A or NTE 116 http://www.nteinc.com/specs/100to199/pdf/nte116.pdf in place.

    Dan
    WA9WVX

  3. #3

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    Quote Originally Posted by WA9WVX;35360

    The one question I have is, Is the RF Linear Amplifier Tube or Solid State (Transistors)?

    I believe your 1000VDC at 10 Amps is slightly an overkill. I would use a 1N4004A or NTE 116 [url
    http://www.nteinc.com/specs/100to199/pdf/nte116.pdf[/url] in place.

    Dan
    WA9WVX
    Thanks Dan. I do not have a linear yet. I am still shopping. I am leaning towards a tube amp like the Ameritron AL811 due to costs. I am not opposed to buying a legal limit used amp, but I am not sure I want to chance buying someone else's boat anchor since I only know enough about electronics to make me dangerous. I have a STBY cable and just ordered a used Ameritron ARB704 interface from fleeBay. I figured I would have to make my own ALC cable (if I need to use one), but was surprised at the email from Ameritron that I did not need one. Seems like a simple cheap enough cable, compared to the costs of a linear. But the FT847 manual did not tell me the value of the diode needed in the cable. Thanks for the diode suggestion. I'll probable get some of those.
    KX4AU

  4. #4

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    Hello Michelle or is it Dalmer M Badgett,

    As you might imagine I'm a bit confused who I'm really consulting with as I went out to the QRZ.com website and discovered this information.

    At this time I would hold back from purchasing a Solid State 1500 W RF Linear Amplifier because you'll need a +50 VDC at 50 to 60 Ampere Power Supply and these are NOT inexpensive compared to a traditional Tube Amplifier. An ARB-704 will interface with your FT-847 transceiver and practically any RF Tube Amplifier and I believe it does the ALC Detecting / Converting to the lower -4 VDC that the FT-847 requires. Since you have stated, "since I only know enough about electronics to make me dangerous" that doesn't give me a Warm & Fuzzy Feeling so be very careful when you're dealing with a high power RF Amplifier as they're Very High Voltages within the Amplifier cabinet. Safety First! These voltages are high enough to kill an individual ... I've always worked around these kind of voltages in my former career in Electronics & Radio Communications. You can make some mistakes but learn and respect the High Voltage!

    Dan
    WA9WVX
    Elgin, Illinois

  5. #5

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    Quote Originally Posted by WA9WVX View Post
    Hello Michelle or is it Dalmer M Badgett,

    As you might imagine I'm a bit confused who I'm really consulting with as I went out to the QRZ.com website and discovered this information.

    At this time I would hold back from purchasing a Solid State 1500 W RF Linear Amplifier because you'll need a +50 VDC at 50 to 60 Ampere Power Supply and these are NOT inexpensive compared to a traditional Tube Amplifier. An ARB-704 will interface with your FT-847 transceiver and practically any RF Tube Amplifier and I believe it does the ALC Detecting / Converting to the lower -4 VDC that the FT-847 requires. Since you have stated, "since I only know enough about electronics to make me dangerous" that doesn't give me a Warm & Fuzzy Feeling so be very careful when you're dealing with a high power RF Amplifier as they're Very High Voltages within the Amplifier cabinet. Safety First! These voltages are high enough to kill an individual ... I've always worked around these kind of voltages in my former career in Electronics & Radio Communications. You can make some mistakes but learn and respect the High Voltage!

    Dan
    WA9WVX
    Elgin, Illinois
    I'm not sure where you got the Michelle from. Friends call me by my middle name, Mitchell, and my log in name is MitchellB, but you are right about my first name being Dalmer. Generally I'll answer to Hey You also. I was five years old before I knew my name was not dam-it-boy.

    I used to be a welder in my former life, so I know about the heat, sparks and the funky dance routine electrical energy can create, but it never hurts to be warned. Thanks.

    So with the ARB704 interface, you agree the ALC cable is not needed?

    If I buy new, I am leaning with the Ameritron AL811 (600 watt max out), which I believe has the power supply built in. That will about max out my toy funds right now, but I am not in a large hurry and may save up for something nicer.

    If I buy used, I'm still trying to familiarize myself with what ever I run across as to value, condition and whether it will work with what I got. I do not have a problem replacing components, but I am not real good at figuring out what needs to be replaced when it is not working. Thanks for the tips and sorry you got confused about my name.
    Mitchell

  6. #6

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    Hello Mitchell,

    OOPS! My mistake on your name ... I looked at your Avatar and assumed (this is very dangerous) that you were a girl / woman, then researching your call letters on QRZ.com I was even more confused. This was strictly my fault and I'm truthfully Sorry it happened.

    Okay I just skimmed over the AL-811 RF Amplifier specifications and MFJ says it produces 600 W PEP Output "almost 2 S Units" which is a lot of baloney being 600 W PEP Output will increase your 100 W PEP from the FT-847 transceiver a + 6 dB to 400 W PEP Output or 1 S Unit plus an additional 200 W PEP Output which is equal to a +3 dB or .5 S Units. Don't get me wrong as the average ham station needs 600 W PEP RF Output to be heard on the other end with our current Propagation / Band Conditions.

    Years ago will say in the 1970s, 1980s & 1990s it was possible to turn your transceiver on 20 m any time day or night with 100 W PEP RF Output and work people all over the world with +10 to +20 over S9 signals, the HF Bands were HOT with the higher Sun Spot numbers and these were average conditions. If the Sun Spot numbers increased which they would from time to time, your signal reports would be +40 to +50 over S9 using only 100 W PEP RF Output so as the Sun Spot decreased there were only two ways to improve your signal, by adding a RF Amplifier and/or putting up a Multi-Band Beam Antenna or both.

    I just read that you'll need a PNP-5M Interface Cable between your ARB-704 Box and the FT-847 transceiver and a homebrew RCA (M) with a Diode to another RCA (M) Connector for the ALC Function to insure everything works correctly with the Ameritron AL811 RF Amplifier.

    Please don't use a heavy duty welding torch on these miniature connectors as I envision them to melt using too much heat. If you have a 50 to 100 W Ungar Soldering Iron and some 60% / 40% Solder that will do the job. The newest Tin Solder is Junk, the connections break all of the time and this is something you don't want to use. Newest doesn't mean it's better, it's only Rohs compliant for the manufactures. Thirty Five years in the Electronic Industry & working for Motorola on Land Mobile Products taught me a whole lot about components and soldering techniques. Good Luck on this RF Amplifier Purchase and installation.

    73,

    Dan
    WA9WVX
    Last edited by WA9WVX; Tue 17th Oct 2017 at 03:24.

  7. #7

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    Quote Originally Posted by WA9WVX View Post
    Hello Mitchell,

    OOPS! My mistake on your name ... I looked at your Avatar and assumed (this is very dangerous) that you were a girl / woman, then researching your call letters on QRZ.com I was even more confused. This was strictly my fault and I'm truthfully Sorry it happened.

    Okay I just skimmed over the AL-811 RF Amplifier specifications and MFJ says it produces 600 W PEP Output "almost 2 S Units" which is a lot of baloney being 600 W PEP Output will increase your 100 W PEP from the FT-847 transceiver a + 6 dB to 400 W PEP Output or 1 S Unit plus an additional 200 W PEP Output which is equal to a +3 dB or .5 S Units. Don't get me wrong as the average ham station needs 600 W PEP RF Output to be heard on the other end with our current Propagation / Band Conditions.

    Years ago will say in the 1970s, 1980s & 1990s it was possible to turn your transceiver on 20 m any time day or night with 100 W PEP RF Output and work people all over the world with +10 to +20 over S9 signals, the HF Bands were HOT with the higher Sun Spot numbers and these were average conditions. If the Sun Spot numbers increased which they would from time to time, your signal reports would be +40 to +50 over S9 using only 100 W PEP RF Output so as the Sun Spot decreased there were only two ways to improve your signal, by adding a RF Amplifier and/or putting up a Multi-Band Beam Antenna or both.

    I just read that you'll need a PNP-5M Interface Cable between your ARB-704 Box and the FT-847 transceiver and a homebrew RCA (M) with a Diode to another RCA (M) Connector for the ALC Function to insure everything works correctly with the Ameritron AL811 RF Amplifier.

    Please don't use a heavy duty welding torch on these miniature connectors as I envision them to melt using too much heat. If you have a 50 to 100 W Ungar Soldering Iron and some 60% / 40% Solder that will do the job. The newest Tin Solder is Junk, the connections break all of the time and this is something you don't want to use. Newest doesn't mean it's better, it's only Rohs compliant for the manufactures. Thirty Five years in the Electronic Industry & working for Motorola on Land Mobile Products taught me a whole lot about components and soldering techniques. Good Luck on this RF Amplifier Purchase and installation.

    73,

    Dan
    WA9WVX
    My avatar is an old chalk drawing I did as a teenager of Linda Ronstadt and Emmylou Harris, so I'm impressed you even noticed it.

    I thought I might need the PNP5M interface cable, but I found a schematic of the ARB704 and decided I could just the old Yaesu CT61 cable (which I have) instead. That way I would have connections for a 2m, 6m and 70cm linear amp later on down the road if I wanted to add them. Where if I used the PNP5M, it uses the same STBY jack from my FT847 but without using the other 3 pins according to the email Ameritron sent me. I'm still not sure if I'll need the ALC cable with this setup or not though.

    I am getting pretty good distance with my setup as it is when conditions are good. I have broken 5000 miles and just this weekend talked to some folks in the AZ QSO party from here in NC. However, I was hoping that a 300 watt or so boost or just a single S unit in talk power from a small linear, may give me a little more clear talk power to those distant stations that I can hear; maybe understand me better and pick me out of a pileup. Last night I heard several contacts from Jamaica clearly, but they seemed unable to hear me, so if I had a little more power, maybe they could have heard me. ?????? I just got a DX Engineering catalog in the mail yesterday and some of those linear amps in there cost more than I paid for my old truck!

    Thanks and thanks for the soldiering tips

  8. #8

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    Hello Mitch,

    You're quite an artist as I looked closer at that Chalk Drawing and I'm impressed. I was thinking that you could probably do some real nice portraits with Oil Paints and Brushes. I'm not that talented although in my younger days, I could free hand do mechanical drawings that were almost as good as the mechanical drawings off of draft board. Some of my managers were impressed although now I cannot draw a thing because my lack of hand muscles -- old age taking it's toll on my body.

    Well I agree with your thinking since you have that Yaesu harness that will help with the 600 W PEP RF Amplifier. You want to use 400 W PEP RF Output to see a minimum of +6 dB or 1 S Unit on the other end where ever that station might be. I'm not sure whether the distance between NC to Jamaica might cause your signal to fall short or skip right over the targeted country. You didn't mention whether you have a multi-band beam antenna or just wire and how high these would be for the take off angle.

    I'm using a 80 thru 6 m Carolina Windom OCF Dipole mounted at 80' with most of my signal going North and South but a month ago Mother Nature came down in the form of Lightning, hit the 120' tower and jumped over hitting my 2 m / 70 cm vertical and my OCF Dipole blowing up both transceivers ... OUCH! September was a bad month for me, first the Lightning hit and then I was taken to the local hospital for Pneumonia / Congestive Heart Failure, these two conditions are so close with the symptoms it's difficult to say which one I had. I've been in the hospital with these conditions so many times I've lost count. I've almost changed my home address from my home to the local hospital. Now if they would allow me to hang some antennas on their roof and bring in a HF transceiver I'd be fine with that.

    BTW, You'll want the ALC connected between your transceiver and the RF Amplifier which prevents flat topping the SSB signal on Transmit. You'll ONLY need a maximum of -4 VDC feeding the transceiver and you should be able to adjust the Transmit ALC for the middle of the meter scale. Distorted Transmit signals will make enemies for you which You don't want.

    73,

    Dan
    WA9WVX

  9. #9

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    Thanks for the compliment on the pic. Growing old sure ain't for the faint of heart. My wife was forced to take a flu shot last week where she works (she gets to retire in 3 months). The next day she got the flu and then I caught it from her. She got better in a couple days, but I am still fighting if. Sorry to hear about your hospital visit and hope all works out for the good soon. Maybe you can take a handheld in there and at least talk on your local repeaters.

    I also use a Windom cut for 40-6m pointing north/south, but it is not nearly high enough (only sitting on a 20' pole at the off-center), but tied off in a tree about 35-40' up. However I am surprised it does as well as it does. I used to have a homemade fan dipole. but the Windom has a lot less tie offs to dodge when mowing and seems to do just as good if not better. I am thinking about buying another 10' section of pipe and at least raising the off-center up to 30', but just not sure if I can get away with it without using extra tie offs. I mostly talk on 40m. I keep a ground block in my shack that I can disconnect my antennas from my radios and screw them into the ground block when weather gets boomy. However, I would feel safer if l put the short to ground block outside the house. I got some inline lightening arresters I keep meaning to install in my coax outside as well, but haven't got around to it yet.

  10. #10

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    Hello Mitch,

    I know exactly what you mean with these Flu bugs ... when my XYL (WB9YCW) gets one, no matter what I do to avoid catching it, I normally do and in my case it hangs on for 2 weeks. She's always in the holiday spirit and says, It's better to Give than Receive! I've got to get her out of that mode.

    As far as your OCF Dipole being at 20,' no sense to raise it since it's working so well. I've got a friend who lives at the base of the Smoky Mountains in Tennessee that uses a IC-735 transceiver and a Collins 30L1 600 W PEP RF Amplifier and has worked stations all over the world using that combination of equipment, He an excellent CW Operator running 35 to 40 WPM has his DXCC and loves to contest. So when you do decide to purchase the AL800 RF Amplifier, I think you'll do just fine.

    I'll need to add RF Surge Protectors at the base of my tower to prevent the Lightning from entering the house. I need to locate a pair of "N" Type connectors for my older 7/8" Heliax for the 2 m / 70 cm band and dig out a pair of PL-259A connectors for the HF bands, ground them to my tower which has 1/2" Ground cable to my Ground Rod ... that's going to be quite a project to do for me to get done with my health problems. Getting old really Sucks ... Enough said. Well, I better cut and hobble away.

    73,

    Dan
    WA9WVX

  11. #11

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    I admire anyone that can do CW. My CW skills are far from being of much used to me yet. It is a slow learn for me. I go though a few months of trying real hard to learn and give it up for a few months and go back again for more tortured learning. Right now I am in one of those off months where I have given up again. I was to the point I knew all the letters, numbers and some of the punctuation, but I had to receive very very slowly between characters to decipher them. I could send better than receive. I'll go back and dive into to it again at some point, maybe when the weather turns cold.

    I got my ARB704 interface yesterday and connected it to my FT847 STBY connection to test to see if the interface XMT light would switch on when I keyed up the transitive and it did. So I'm assuming it works, but I do not have an amp to test it with yet.

    Yea, I feel your pain about the getting old. My last antenna I put up was my 40-6m Windom and I tried to rope it off so that I would not need to climb a ladder to fix it in the future. One end is roped though a pulley on the top corner of the house that I can lower it to the ground and the other end is a rope pulled up though a tree that can also be lowered. The off-center feed line is supported by 20' of pipe that is tied against our picnic shelter, that I can be laid down if needed and I buried the coax underground so my lawnmower would not chop it up. Unfortunately my 2m & 70cm ground plane antennas are mounted to the peak & eves of our house an require a 24ft ladder to get to. However they have worked fine for over 20 years and only had to come down once a few years ago when I made aluminum soffits, fascias and eves around the house and install gutters and downspouts. The intention was to later install vinyl siding next, but that has not happened yet and I doubt my crappy knees will let me now. Besides, my wife has a long list of other Honey Dos she still thinks I'm able to do.

  12. #12

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    Hello Mitch,

    I did a similar thing with my OCF Dipole at 80'. I had a (woman) tower climber put a 12' x .125" aluminum pipe through my tower at 80' with a "EYE Bolt" and a small pulley using Black Dacron UV Stabilized Rope and set it up like a wash line so I could raise and lower the center to the ground and back up again without climbing the tower. I purchased a couple of Baluns 4:1 & 1:1 from Balun Designs in Texas, they're rated at 3 KW+ RF Power and they're Current Type Baluns. I discovered that I should have ordered a 6:1 instead of a 4:1 Balun because of the height above ground and naturally this was after the fact.

    I got out my squirt gun loaded with water and shot my left foot off ... it was soaked with water! Some how I still wonder how I overlooked that matching issue. Palm to my forehead. A friend and I attached the Baluns to the rope using Black Ty-Raps and that part of it worked out to my liking. The wires from the upper Balun were tied off to a Maple tree in my front yard and a Popular tree along the back property line using "EYE Bolts, a Spring and a Pulley" into the trees) as I think they're wood. That antenna has been up for 6 years now. Our local Hawks like the horizontal pipe as they get a Bird's Eye View of the rural sub-division.

    I know exactly what you mean about our wives having "Honey Do List!" Mine stretches down our refrigerator, across the kitchen floor and into our foyer and she keeps adding things to my list ... I'll be still doing things after I die. Well, I better get to those projects before she takes my keyboard away. :vO

    73,

    Dan
    WA9WVX
    Last edited by WA9WVX; Thu 19th Oct 2017 at 21:58. Reason: TYPOS

  13. #13

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    I got those 1N4004 Rectifier Diodes in the mail recommended to make up my ALC cables. They were pretty cheap (about 6 cents each), but I got way more than I'll ever use.

    Last night there was a used Ameritron AL811 amp on eBay. It is supposed to be in good working condition, from a working shack and the pics look like it is physically in almost new condition. I only bumped the bid up $10 over the current bid (at the last minute) and really did not expect to win it, but I did. Even with shipping it is about 35% off of the best price I have found for a new one. However, this morning I got a reply from Ameritron about the serial number and they said it was made in the mid-1990s as their serial numbers only go back to 2001. I did not expect it to be quite that old. I hope the previous ham kept it maintained. I don't want to dig deeper in my pockets to buy new caps and tubes, so I hope it works when it arrives.

    Now I need to learn how to properly adjust it, so I can at least test it to make sure it does work and I will not need to start a return/refund. I've never used a linear before.

  14. #14

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    I have made up my ALC cable with the diode. I have also been making grounding wires for the AL811 & ARB704. I ran into a problem with my shelf above my little desk. I had to raise it with a pair of 2x4 blocks to get enough space under it to sit the 8" tall AL811 according to the case size specs online. Now I got 8.5" so hopefully it will fit. I had to cut down my wooden tilt stand my antenna tuner was sitting on so I could slide it to the left of my desk underneath the mic boom clamp on my shelf that hangs down about 3.5" below the shelf. This makes room to fit the AL811 on my desk between my transceiver and antenna tuner.

    This new (old) AL811 Amp is due to arrive by the end of this month by the eBay delivery date. I have also been trying to learn how to properly adjust it and test it when it arrives. I found this video on utube that gives a good description in part II toward the end about how to use the ALC and control it on the AL811. It is difficult to hear him clearly as he seems far away from his mic and there is a lot of background hiss, but good instruction otherwise.

    https://www.youtube.com/watch?v=OT1UaCrVvd4

    Anyone know of another good tune up procedure, I'd love to hear it.

  15. #15

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    My amp arrived yesterday. However, although it was double boxed and well cushioned, it needed it. USPS had crushed the box pretty good and it looked as though it had been thrown around.
    AL811_3658 smaller.jpg
    The amp on the outside survived the ride, but when I took it out, I could hear something rattling inside, so I removed the screws/cover to take a look. The first tube on the left had come completely out of it's socket and was laying horizontally. The second tube from the left had raised about half out of it's socket, but could easily be pushed back down. I could see nothing else out of place. I carefully reinserted the first tube into it's socket and got a light to inspect everything closer. That is when I discovered that there should be 2 tiny coils on top (inside) of each tube. The first tube had only one coil and I could see the other coil laying at the bottom inside the tube.
    AL811_3651 smaller.jpg
    I don't know much about tubes, but I'm pretty sure this tube would have to be replaced before I tried to plug the amp in to test it. I made a deal with the seller to refund me enough to pay for a new set of 3 tubes that are now on order.
    AL811_3654 reduced.jpg
    I also noticed that that this amp has the 10/12 meter mod done to it internally, so that is nice to know.
    AL811_3657 reduced.jpg
    I tried to carefully remove the ceramic cap from atop the first tube, but to my surprise, the metal tip of the tube (not sure what it is called) was so corroded inside the ceramic cap that is pulled off the tube and is still inside the cap. I started another thread about that, but I need some ideas on how to remove the other two caps from the remaining tubes and hopefully save the tubes & caps? Any suggestions?

  16. #16

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    I ended up giving the broken tube tip/cap a shot of WD40 and wiggled it out of the ceramic cap with a pair of pliers. The corrosion was not as bad as I first though; mostly just enough to cause them to stick. Once broken loose it came out as normal. The other two I gave a quick shot of WD40 under the cap using the plastic spray tube on the spray can so I could spray it up under the cap. After sitting a few minutes, they broke loose with gentle wiggling and also released as normal. I was able to save those tubes and they appear brand unburned new National Electronics Russian tubes. I'll save those for spares.

    After doing some more research on setting up and tuning a linear, I discovered that my antenna tuner's wattmeter is not going to allow me to properly tune the AL811 since it maxes out at 300 watts. Original plan was to set the amp/transceiver up for a maximun output of 300 watts until I can afford a larger antenna tuner to get full use of the amp. I can still do that, but before I can back the output down on my transceiver to where the amp is only putting out 300 watts, I first have to tune it up at maximun output which should be around 600 watts (more than my tuner) so I broke into my piggy bank to order a MFJ-891 2000 watt wattmeter last night. It is not a great wattmeter by the reviews I read online, but for what I expect to need, it should suffice and I could afford it.
    mfj891 front.jpg
    I'll update again when the new tubes & wattmeter arrive.

  17. #17

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    Hello Mitch,

    Well since the Seller shipped the RF Amplifier in two boxes that's a good thing although using USPS was a Bad Idea as you've found out. Hind sight is always 20 / 20, had I shipped that amplifier, I probably would have put Pink Insulation into the RF Deck to prevent the tubes from bouncing loose. The missing Coils on the Ceramic Plate Caps will need to be replaced "if" you cannot find them. These Coils prevent RF from getting back into the amplifiers DC circuits. You can contact Ameritron at http://www.ameritron.com/ or Call #1-662-323-8211 and ask for the Parts Department. Ameritron provides Customer Support too. I hope you have a 600 Watt 50 OHM RF Dummy Load to connect to your RF Amplifier, this way you can test the amplifier without worrying about Jamming other Operators on the HF Bands. From the sounds of it, you've got some sort of a Automatic Antenna Tuner that handles ONLY 300 W of RF output. Well with the 50 OHM RF DUMMY LOAD, you should be able to set the RF Drive Level on your transceiver so you don't Over Drive the ATU while using the A811H RF Amplifier.

    Dan
    WA9WVX

  18. #18

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    Quote Originally Posted by WA9WVX View Post
    Hello Mitch,

    The missing Coils on the Ceramic Plate Caps will need to be replaced "if" you cannot find them. These Coils prevent RF from getting back into the amplifiers DC circuits.

    I hope you have a 600 Watt 50 OHM RF Dummy Load to connect to your RF Amplifier, this way you can test the amplifier without worrying about Jamming other Operators on the HF Bands.

    From the sounds of it, you've got some sort of a Automatic Antenna Tuner that handles ONLY 300 W of RF output. Well with the 50 OHM RF DUMMY LOAD, you should be able to set the RF Drive Level on your transceiver so you don't Over Drive the ATU while using the A811H RF Amplifier.

    Dan
    WA9WVX
    Is this one of the coils you are referring to?
    AL811_3653 reduced.jpg
    If so, I have all three attached to the ceramic caps.

    Well, at least I am getting a new trio of vacuum tubes for it because the seller did not remove the cover and cushion the tubes for transport.

    I have a homemade oil filled dummy load that I made a few years ago, that should handle the power, at least in short bursts.
    9-25-15_dummy load 2 reduced.jpg

    My antenna tuner is a MFJ969 manual tuner. It works great, but 300 watts is the max on it unfortunately, which is why I thought I needed to order the 2000 watt wattmeter to properly tune the AL811 before reducing the drive to get my 300 watts out so I can reconnect my tuner. I'm still learning, but that's half the fun. Thanks for the tips.

  19. #19

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    Hello Mitch,

    Those RF Coils were exactly what I was talking about so you're good there. I didn't realize that you had a manual ATU but it does work for your current situation. I'm at a cross roads recommending a higher power RF Tuner ... Here's an older Dentron Manual ATU https://swap.qth.com/view_ad.php?counter=1344785 This Tuner will tune a door knob on a door, is built like a Tank, most hams that have one won't part with theirs. I'm not sure about the Prices this ham has published but he's out in Vian, Oklahoma.

    I originally had a MFJ-989 ATU and a G5RV antenna. The antenna was a MFJ Made antenna and it worked great with the tuner. The only problem was the fact that the G5RV antenna would blow apart in our winds. I then researched a Carolina Windom OCF Dipole 80 thru 6 m antenna and built my own. This antenna is mounted at 80' and has been up for over 6+ years without any major problems. I can raise and lower the antenna from ground level no climbing required. The main lobes favor North and South but I've been able to use it in other directions with a little less of a signal. These antennas are 133' long not including the UV Stabilized Ropes holding the ends of the wire up above the ground.

    One thing you will learn over time, ALL antennas are compromises on the individual bands.

    That homebrew RF Dummy Load looks very interesting as I've never seen one like that before. I wonder where you found the design? Most 1.5 to 2 KW RF Dummy Loads are made with some sheet metal and 1 gallon brand new empty paint can. Unless you're independently wealthy and can purchase a BIRD Commercial 1.5 kw or larger 50 Ohm RF Dummy load. Brace yourself when you open up the web links:

    https://www.ebay.com/itm/Bird-HF-VHF...cAAOSwmvZZb4MI

    https://www.ebay.com/itm/New-Bird-88...EAAOSwLEtYh~ea

    https://www.ebay.com/itm/New-Bird-82...TqONh-WpMC2ejQ

    For some reason I think you'll settle for your homebrew RF 50 OHM Dummy Load.

    Dan
    WA9WVX
    Last edited by WA9WVX; Tue 31st Oct 2017 at 18:30.

  20. #20

    Default

    Hey Dan

    That Deltron looks like a nice tuner, and in my price range - well, maybe next year; but I got my heart set on one with a roller inductor. I'm kicking myself now for not biting the bullet and paying the difference for a 1500 watt model when I got the MFJ969 300 watt tuner, but I kept telling myself I'll never need more than a 100 watts.

    Bird seems to be the wattmeter everyone raves about, but I just want to tune up my amp and do not need anything that accurate, nor can I afford one.

    That dummy load design I found online somewhere in 2015 and adapted it to use with the material I just happened to have on hand and filled it with mineral oil. It works great, but I don't have a clue as to how much power it will take, but I used it to practice CW with and never had a problem using it long hours on low power. I hope by being slow and careful it will work sporadically on the 600 watt max the AL811 puts out good enough to tune it up.

    Today my new vacuum tubes arrived from DX Engineering and put the cover back on the amp. I got it hooked up between my transceiver, tuner and interface just to test it out that everything lights up, and the meters move as the instructions indicate they should. I can't go any further than that until my new meter arrives. The fan is quite, LEDs & tubes lights up and meters move. I am pleased so far, as I think I got a used amp with new tubes. However, it sure is a tight fit on my little desk with my computer & phone too.
    desk reduced.jpg

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