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Post by Afterburner(OT-749) on Mar 6, 2016 8:23:29 GMT -5
OK ... We here in West Virginia sometimes do things with major gusto. A fellow CB operator that lives not far from me here erected a 120' free standing tower with a Laser 500 on top. Now the issue he is having.
He is running a RCI 2995 that is set to dead key at 2 - 3 watts but swings 80 - 100 with audio. From there his coax goes to a X-Force 400 transistorized amplifier which in turn is the driver for a Wizard Built 3cx3000a7.
Testing SWR's with coax plugged into radio only he has a 1:1 to 1 SWR. Coax connected to the X-Force 400, SWR's same results. The previous is results are connected to the antenna directly or into a dummy load. now the confusing part ... if he checks SWR's on the output side of the Wizard box with radio connected to X-Force 400 feeding into Wizard 3cx3000a7 but just "passing" through the Wizard box, not powered on, his SWR climbs to 1:8 to 1. He has not ever powered the Wizard box on and checked SWR's as he is afraid of blowing up that expensive box.
The other part of the equations is this ... he has had to replace the "pills" in that X-Force box more times than you can shake a stick at it. More times to the point that he actually has 2 additional X-Force boxes as spares. as he blow's the "pills" out of one, he hooks up another and sends the one to get new pills installed.
He is using an MFJ 259B meter that gives him SWR and Ohms readings. He has also tried using different dummy loads testing, plug on and oil can type with the same results. As far as him blowing the "pills" in the X-Force, I have told him in my opinion that even though he has the dead key in the radio turned down, the PEP out of the radio is too much for the X-Force and that is why the issue for causing the malfunction in it but that still does not explain the high SWR in the end coming out the Wizard box.
Other factors that may or may not play into the equation. His antenna/tower is approx. 1200 feet away from his home on top of a ridge. Don't know what the type coax that he is using but it is best part of 2" in diameter and has one single line feeding up to tower where there is a electronic switch box mounted controlled from his home that on the other side of that switch box are two same type coax coming out, one to vertical, one to flat side. Ohms reading in the house from all that coax is 49.1 ohms which actually surprised me but I saw that reading on his meter. The setup in his home is that the radio is in one room on a desk. from the radio, the coax goes down through the floor and comes up in a smaller different room that has A/C running in it whenever needed and has one large extraction fan pulling the moving air from two other fans that blow's cooling air across the X-Force and Wizard box constant. He does not have to get up from his desk to turn anything on or off as he has everything setup through a "control panel" at his desk. Everything is grounded, I mean everything, and no two grounds are tied together, each is separate. That is everything in the house and the antenna/tower is grounded.
Any idea's why the high SWR's coming out the other side of the Wizard box? Any suggestions/input is appreciated.
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Post by Night Ranger on Mar 6, 2016 10:35:19 GMT -5
OK ... We here in West Virginia sometimes do things with major gusto. A fellow CB operator that lives not far from me here erected a 120' free standing tower with a Laser 500 on top. Now the issue he is having. He is running a RCI 2995 that is set to dead key at 2 - 3 watts but swings 80 - 100 with audio. From there his coax goes to a X-Force 400 transistorized amplifier which in turn is the driver for a Wizard Built 3cx3000a7. Testing SWR's with coax plugged into radio only he has a 1:1 to 1 SWR. Coax connected to the X-Force 400, SWR's same results. The previous is results are connected to the antenna directly or into a dummy load. now the confusing part ... if he checks SWR's on the output side of the Wizard box with radio connected to X-Force 400 feeding into Wizard 3cx3000a7 but just "passing" through the Wizard box, not powered on, his SWR climbs to 1:8 to 1. He has not ever powered the Wizard box on and checked SWR's as he is afraid of blowing up that expensive box. The other part of the equations is this ... he has had to replace the "pills" in that X-Force box more times than you can shake a stick at it. More times to the point that he actually has 2 additional X-Force boxes as spares. as he blow's the "pills" out of one, he hooks up another and sends the one to get new pills installed. He is using an MFJ 259B meter that gives him SWR and Ohms readings. He has also tried using different dummy loads testing, plug on and oil can type with the same results. As far as him blowing the "pills" in the X-Force, I have told him in my opinion that even though he has the dead key in the radio turned down, the PEP out of the radio is too much for the X-Force and that is why the issue for causing the malfunction in it but that still does not explain the high SWR in the end coming out the Wizard box. Other factors that may or may not play into the equation. His antenna/tower is approx. 1200 feet away from his home on top of a ridge. Don't know what the type coax that he is using but it is best part of 2" in diameter and has one single line feeding up to tower where there is a electronic switch box mounted controlled from his home that on the other side of that switch box are two same type coax coming out, one to vertical, one to flat side. Ohms reading in the house from all that coax is 49.1 ohms which actually surprised me but I saw that reading on his meter. The setup in his home is that the radio is in one room on a desk. from the radio, the coax goes down through the floor and comes up in a smaller different room that has A/C running in it whenever needed and has one large extraction fan pulling the moving air from two other fans that blow's cooling air across the X-Force and Wizard box constant. He does not have to get up from his desk to turn anything on or off as he has everything setup through a "control panel" at his desk. Everything is grounded, I mean everything, and no two grounds are tied together, each is separate. That is everything in the house and the antenna/tower is grounded. Any idea's why the high SWR's coming out the other side of the Wizard box? Any suggestions/input is appreciated. He may have out of band harmonics that are being generated by the amplifier (probably the X-Force), and they are being reflected back from the antenna. Place the SWR meter after all the amps and between the antenna, and check the SWR. Next place a low pass filter between the last amp and the SWR meter and antenna. If the SWR falls back to near 1.1/1 after the low pass filter is installed then one of the amps (probably the X-Force) is generating out of band harmonics that are outside of the CB band and above the cut off frequency of the low pass filter. Coppers sells the DF3000 low pass filter reasonably. It will not be able to handle the output of a 3cx3000a7 amplifier, but it could be placed between the X-Force and the 3cx3000a7 amplifier. The best solution is to repair the amplifier generating the out of band harmonics. DF3000 3KW Low Pass Filter www.copper.com/cart/DF3000-3KW-Low-Pass-Filter?search=low%20pass%20filter&description=true&sub_category=true-Night Ranger |
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Sandbagger
Administrator/The Boss 
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Post by Sandbagger on Mar 7, 2016 7:59:55 GMT -5
OK ... We here in West Virginia sometimes do things with major gusto. A fellow CB operator that lives not far from me here erected a 120' free standing tower with a Laser 500 on top. Now the issue he is having. He is running a RCI 2995 that is set to dead key at 2 - 3 watts but swings 80 - 100 with audio. From there his coax goes to a X-Force 400 transistorized amplifier which in turn is the driver for a Wizard Built 3cx3000a7. Testing SWR's with coax plugged into radio only he has a 1:1 to 1 SWR. Coax connected to the X-Force 400, SWR's same results. The previous is results are connected to the antenna directly or into a dummy load. now the confusing part ... if he checks SWR's on the output side of the Wizard box with radio connected to X-Force 400 feeding into Wizard 3cx3000a7 but just "passing" through the Wizard box, not powered on, his SWR climbs to 1:8 to 1. He has not ever powered the Wizard box on and checked SWR's as he is afraid of blowing up that expensive box. The other part of the equations is this ... he has had to replace the "pills" in that X-Force box more times than you can shake a stick at it. More times to the point that he actually has 2 additional X-Force boxes as spares. as he blow's the "pills" out of one, he hooks up another and sends the one to get new pills installed. He is using an MFJ 259B meter that gives him SWR and Ohms readings. He has also tried using different dummy loads testing, plug on and oil can type with the same results. As far as him blowing the "pills" in the X-Force, I have told him in my opinion that even though he has the dead key in the radio turned down, the PEP out of the radio is too much for the X-Force and that is why the issue for causing the malfunction in it but that still does not explain the high SWR in the end coming out the Wizard box. Other factors that may or may not play into the equation. His antenna/tower is approx. 1200 feet away from his home on top of a ridge. Don't know what the type coax that he is using but it is best part of 2" in diameter and has one single line feeding up to tower where there is a electronic switch box mounted controlled from his home that on the other side of that switch box are two same type coax coming out, one to vertical, one to flat side. Ohms reading in the house from all that coax is 49.1 ohms which actually surprised me but I saw that reading on his meter. The setup in his home is that the radio is in one room on a desk. from the radio, the coax goes down through the floor and comes up in a smaller different room that has A/C running in it whenever needed and has one large extraction fan pulling the moving air from two other fans that blow's cooling air across the X-Force and Wizard box constant. He does not have to get up from his desk to turn anything on or off as he has everything setup through a "control panel" at his desk. Everything is grounded, I mean everything, and no two grounds are tied together, each is separate. That is everything in the house and the antenna/tower is grounded. Any idea's why the high SWR's coming out the other side of the Wizard box? Any suggestions/input is appreciated. I'm sitting here trying not to cringe, with images of "all knobs being turned to the right" and smoke being the result. There are so many things about this setup that I just can't endorse. A 3 watt deadkey with a 90 watt peak, is a 30:1 peak to carrier ratio which greatly exceeds that which allows for clean audio. With that much swing, you might as well be on SSB. Driving that into a what I am assuming is a 4 "pill" (and class "C"  )amplifier, and there is no doubt in my mind what is causing him to blow the "pills" out. A straight, single stage 4 pill box can be driven to a maximum clean peak power output with less than 30 watts peak, with a 5 or 6 watt carrier. At that point (assuming 2879 transistors), you should be looking at a realistic maximum of 650 - 700 watts of peak power. Driving a 3CX3000 with that much power is probably not a good idea either. If it were me, I'd ditch the X-force and drive the Wizard directly with the radio (after turning up the dead key to at least 10 watts). That may be a little light on the drive, but the tube will thank him, and the SWR problem, I suspect, will go away. Now to that specifically...... While a 1.8:1 SWR is not dangerously high (Heck, anything under 2:1 is considered acceptable in most circles), the fact that it's changing from what was tested on the antenna itself is demonstrating a change in the system parameters. It could be a couple of things. It could be a subtle impedance change when the Wizard amp and the extra coax jumper is installed. SWR meters typically measure forward and reflected RF voltage, and it tends to change depending where in the feedline, the meter is inserted. If the jumper length is changed and the SWR reading changes with it, this is the likely cause. The other possibility is what Night Ranger alluded to, and that is an instability in the X-force amp, causing out of band spurious emissions power adding and reflecting back. Since the spurs are usually at frequencies where the antenna is not resonant, the SWR at the spur frequency will be bad, which is why most of the spur's power reflects back. But since a watt or SWR meter is not frequency selective, it will show all forward and reflected power regardless of frequency, which is displayed as an increased SWR. Replace the X-force amp with a barrel connector and see if the problem goes away. If it does, then do what Night Ranger suggested with a low pass filter. |
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Post by BBB on Mar 7, 2016 16:12:37 GMT -5
Only way to tell for sure that he's got extra harmonics being generated is with a Spectrum Analyzer tool. Extra Harmonics = Heat = Smoke. I've had my X-Force heavy duty (4) 2879 box for over 5+ years and no smoke yet (fingers crossed) Yes I have a YA-1 low pass filter good to 5KW PEP inline and run the amp at peak from time to time, but always visually monitor for harmonics on the output. With all the money he has invested in quality amps, a used Spectrum Analyzer would be cheap insurance. In the past,they cost over $500+. If you already have a decent PC, they currently offer USB Dongle based spectrum analyzer units for under $100. If you can afford an antenna analyzer and a watt meter you can afford one of these. There's no excuse now. I don't understand why these folks running high power don't get the Spectrum Analyzer thing. Heck all you have to do is hook a telescopic antenna to the front of the thing and it's completely visual, no math required. As a bonus, you get lower VSWR, longer component life and get to keep most of your output power on frequency, imagine that! Instructions: See spurs, cut it back or else. Little to no spurs present, your good to go, go, go  www.dxengineering.com/parts/bnr-ya-1www.ebay.com/itm/USB-RF-Spectrum-Analyzer-1-8-GHz-RF-Viewer-by-Nuts-About-Nets-/262039733209?hash=item3d02c903d9:g:lTMAAOxy63FS~LSEThis is the Spectrum Analyzer I use. It takes up very little real estate on the bench. www.atecorp.com/ATECorp/media/pdfs/data-sheets/Wavetek-JDSU-SDA-4040D_Datasheet.pdfwww.ebay.com/itm/JDSU-WAVETEK-SDA-4040D-STEALTH-DIGITAL-ANALYZER-No-Accessories-Calibrated/261320066228?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20131003132420%26meid%3D2a145b49c09849578e40cbeec9abeafa%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D150671245949 |
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Post by 2600 on Mar 12, 2016 1:20:13 GMT -5
Simple fix:
Lose the driver.
The radio straight into the three-by-three may only get you half the power it can deliver, but the audio will be outstanding.
Well, if the radio alone doesn't sound right this won't improve it.
I suspect the real focus of the trouble lies with the driver. It's too big to start, and I won't even start on the harmonic issue.
The guy needs to decide what he wants. Audio or a big meter reading.
If he wants to talk to the wattmeter, who cares what it sounds like?
If he wants to be loud, lose the driver. Nobody will know that your wattmeter reading fell in half. Nobody but the guy sitting in front of it. Nobody's S-meter will reveal a change of any significance.
But hey, if he wants to spend all that money just so he can talk to a meter, it's his money to burn.
73
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Post by bill on Mar 21, 2016 20:01:05 GMT -5
Let him borrow one of your Guns and then you can buy his Equipment cheap from the Widow  |
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Post by cornbrown on Jun 10, 2016 13:02:54 GMT -5
OK ... We here in West Virginia sometimes do things with major gusto. A fellow CB operator that lives not far from me here erected a 120' free standing tower with a Laser 500 on top. Now the issue he is having. He is running a RCI 2995 that is set to dead key at 2 - 3 watts but swings 80 - 100 with audio. From there his coax goes to a X-Force 400 transistorized amplifier which in turn is the driver for a Wizard Built 3cx3000a7. Testing SWR's with coax plugged into radio only he has a 1:1 to 1 SWR. Coax connected to the X-Force 400, SWR's same results. The previous is results are connected to the antenna directly or into a dummy load. now the confusing part ... if he checks SWR's on the output side of the Wizard box with radio connected to X-Force 400 feeding into Wizard 3cx3000a7 but just "passing" through the Wizard box, not powered on, his SWR climbs to 1:8 to 1. He has not ever powered the Wizard box on and checked SWR's as he is afraid of blowing up that expensive box. The other part of the equations is this ... he has had to replace the "pills" in that X-Force box more times than you can shake a stick at it. More times to the point that he actually has 2 additional X-Force boxes as spares. as he blow's the "pills" out of one, he hooks up another and sends the one to get new pills installed. He is using an MFJ 259B meter that gives him SWR and Ohms readings. He has also tried using different dummy loads testing, plug on and oil can type with the same results. As far as him blowing the "pills" in the X-Force, I have told him in my opinion that even though he has the dead key in the radio turned down, the PEP out of the radio is too much for the X-Force and that is why the issue for causing the malfunction in it but that still does not explain the high SWR in the end coming out the Wizard box. Other factors that may or may not play into the equation. His antenna/tower is approx. 1200 feet away from his home on top of a ridge. Don't know what the type coax that he is using but it is best part of 2" in diameter and has one single line feeding up to tower where there is a electronic switch box mounted controlled from his home that on the other side of that switch box are two same type coax coming out, one to vertical, one to flat side. Ohms reading in the house from all that coax is 49.1 ohms which actually surprised me but I saw that reading on his meter. The setup in his home is that the radio is in one room on a desk. from the radio, the coax goes down through the floor and comes up in a smaller different room that has A/C running in it whenever needed and has one large extraction fan pulling the moving air from two other fans that blow's cooling air across the X-Force and Wizard box constant. He does not have to get up from his desk to turn anything on or off as he has everything setup through a "control panel" at his desk. Everything is grounded, I mean everything, and no two grounds are tied together, each is separate. That is everything in the house and the antenna/tower is grounded. Any idea's why the high SWR's coming out the other side of the Wizard box? Any suggestions/input is appreciated. How long are your coax jumper lengths between driver and Big Box? Get the input tuning of the xforce box checked if that's good make sure to use a 6foot coax jumper or 11foot 9inches length jumper between the Xforce box and the Wizard big box. The Wizard has an input tuner used to tune your SWR between your driver and wizard when the Wizard is on and being keyed! Get a Bird dual line sectiion on the output of the Xforce Driver, with 25watt slug to read your reflected watts, and a 1000 watt slug to read your forward watts from your Xforce Driver. Using the Input tuning Knobs on the Wizard with the Wizard Keyed tune for Lowest reflected watts on the Bird and highest Forward watts on the Bird from the Xforce Driver and Output forward Watts from the Wizard Box. You will also need a Bird meter hooked to the output of the WiZard Box with a 10Kwatt slug and peak kit installed, Use the TUNE and LOAD Knobs on The Wizard to Tune for Highest forward watts out on the Bird Meter, Go back and touch up the input tuning again for lowest reflected and highest forward watts from the xforce driver, when tune up is done set your driver to key about 2000watts peak and cruise the wizard at about 7000watts peak. Hot Dog. I Just made a MUDDUCK 10-8. Good Luck. |
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)amplifier, and there is no doubt in my mind what is causing him to blow the "pills" out. A straight, single stage 4 pill box can be driven to a maximum clean peak power output with less than 30 watts peak, with a 5 or 6 watt carrier. At that point (assuming 2879 transistors), you should be looking at a realistic maximum of 650 - 700 watts of peak power. Driving a 3CX3000 with that much power is probably not a good idea either. If it were me, I'd ditch the X-force and drive the Wizard directly with the radio (after turning up the dead key to at least 10 watts). That may be a little light on the drive, but the tube will thank him, and the SWR problem, I suspect, will go away. Now to that specifically......
