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Kf4gyp
Junior Member
Username: Kf4gyp
Post Number: 11
Registered: 11-2009
| | Posted on Monday, February 01, 2010 - 7:36 pm: | 
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how much money would it cost to build an amp with 4 of these tubes biased ab class so that I could achieve 30,000 watt dead key and swing up from there to say 60,000 to 90,000 watts include all power supply,coax,antenna ect.
73 Ray/Hawk-Eye
DE KF4GYP
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Patzerozero
Senior Member
Username: Patzerozero
Post Number: 4787
Registered: 7-2004
| | Posted on Tuesday, February 02, 2010 - 12:26 am: |
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first, if ya gotta ask......and second, running that in ABSOLUTELY no way compares to running a 3-500z base amp.
that said, 4cx5000a's can probably be had new for under $1500 each. the handful of parts required to build the amp probably cost a mere several of hundreds of dollars more. it's the power supply & how to get the power from the source to the amp that starts costing bucks.
getting the power company to run the 3 phase 440 or 660 into the house is going to be a trick, into a commercial establishment will be easier. the transformer network required to run this on 220v is going to run into even bigger bucks and you still need to get the required current draw taken into consideration. so, the power supply shouldn't cost all that much more then the 4 tubes, the power souce may add who knows how much. now, who is going to build it? if you can't, that could run into more thousands, and even then, the guys who build that type of amp for an end user are pretty fussy about you knowing exactly what you're doing with it. an angineer that uses these tubes at a commercial AM BC station number one has the power delivered and PLANNED for, and again, just because he uses it in his BC xmtr, doesn't mean he'd have a clue as to how to use it on CB. the builder doesn't want any connection to a fried cber. so now you're probably in the $12k range, you still don't have voltage, cable, coax, antenna, etc.
so, the feedline i've seen used in 25-50kw mobiles is a hardline, with solid angled connectors. what is it? don't know. run rg217 or 218 up to 10kw, & that stuff works just fine with 5x16 2879 transistor amps. i've been told by the owner of a certain local 25kw suburban that his feedline system cost him over a grand, and that was with him installing it. we're not talking too many feet here, either. the fist sized connectors were several hundred bucks each. as for the antenna, that's probably the cheapest & easiest part. remember your 100kw connectors & all you need is tubing of sufficient diameter to hold up under 100kw peaks, and a matching section that'll do the same. and it needs to be tuned just right. close enough won't cut it. a half wave direct fed dipole will cost you the cost of 18' of solid aluminum rod, plus again, the matching network. maybe a few hundred bucks more.
so parts-wise, you could be looking in the $15000+ range. a saavy shopper can do it for less  . labor? who knows what that will cost you. and who knows if anybody would build it for you. kinda like the race car engine builder.....they either don't race or they don't build engines for anyone but themselves. can't say i know of anyone in particular using that tube & wouldn't know why they don't. do know of quite a few 3x tube amps out there, and 4cx3000, 12000, 15000 and even 40000. several 3cx20000 amps use water cooling systems.
there are a LOT of 10kw-25kw mobile amps around, and even a few approaching 100kw. for every qrz post that says it can't be done.....nobody said it's BCB quality, and you'll soon realize how many hams don't realize electrical power doesn't just come out of a wall socket or 12v battery, it CAN be GENERATED. and NO, there is not a standard rg8 size coax that'll handle 3kw-10kw-50kw, it is done in other ways. so don't let anyone tell you it can't be done, but if you want it....mortgage the house if you can't build it yourself. hence my opening....if ya gotta ask.....
one last question....where do you plan to use this? CB? far less then 100kw will make you king of the hill more often then not. there are 100kw stations out there that are NOT king of the hill 100% of the time, and 25kw is barely 1 S-unit less in carrier then 100kw, and you have a VERY GOOD chance of getting past a 100kw station with 6db less more often then you think.... |
Tech833
Intermediate Member
Username: Tech833
Post Number: 135
Registered: 12-2001
| | Posted on Tuesday, February 02, 2010 - 12:40 am: |
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Biased AB (push-pull), a quad of 4CX5000a's would only be good for about 10 KW carrier.
That assumes 2 parallel working against 2 parallel class AB1.
A single 4CX5000 running class C is good for 10 KW carrier on SW frequencies. So a quad of 4CX5000s would be good for around 40 KW carrier power.
But, you are a LOT better off running the appropriate sized tube by itself in the first place, like a 4CX35000, instead of a bunch of smaller tubes in parallel. That would give you 60KW carrier and easily make positive peaks over 120 KW depending on your power supply.
Your radio 'Mythbuster' since 1998
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Ironmike
Junior Member
Username: Ironmike
Post Number: 38
Registered: 6-2007
| | Posted on Tuesday, February 02, 2010 - 9:29 am: |
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When I lived in Florida the AM station down the street sat vacant for several years. So there's your real estate, towers, and power feed 
Seriously they did throw away a pile of 1 1/4" heliax that I snagged. It may still be in the shed. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 4791
Registered: 7-2004
| | Posted on Tuesday, February 02, 2010 - 3:41 pm: |
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Τετάρτη, 21 Μαΐου 2008
JOHN 5-19 LAMIA *HIGH POWER AMPLIFIER 4CX5000A
An AM Transmitter Modification and Construction Project.
My Linear is a class AB1 high frequency amplifier utilizing the Eimac 4CX5000A power tetrode. It is operating on the 176m. A 4CX5000a will work in the circuit with little modifications Power output over 10kw could then be expected. Power was measured with a Bird 43 wattmeter and a 10 KW slug (Frequency Band 0.45-2.5 mhz)
HOME MADE LINEAR AMPLIFIER 4CX5000A
...................... 1690 KHZ AM
This is a 4CX5000a grid driven amplifier that is built like a tank. The unit is considerably over designed as can be seen in the pictures documenting the construction. The unit requires a separate screen power supply and High Voltage power supply. The documentation indicates a well thought out design and construction technique.
Output Power
In order to achieve full power output over 10000 watts continuous carrier, an input power approximately 10 to 40 watts is required. If your delivers more output power, reduce the drive level.
For the amplifier RF output, I used an LC type connectors at the time of construction. The LC type seems to handle the power levels without any problems (so far!).
try googling 'john 5-19 lamia' or '4cx5000a tube specs', kf4gyp, & you'll find info on a greek AM BCB running 1 of these tubes at 10k carrier power, so at 27 mhz 4 of then should be able to produce around 60-70% of 4x, or in the 30kw carrier range. it will also take more then 40 watts to drive each one at higher freqs then at under 2 mhz. and yes, the 'big boys' rarely-though occasionally-use multiple tubes in their big amps.
as i alluded to previously, there is a well known rap star/CBer that runs an amp built around a 4cx40000 tube. obviously capable of surpassing 100kw, nobody has actually claimed that he has the power source to do it, himself included. the youtube soundbites are well known, and on the east coast i have heard washington state multi hop E skip cover up 20 over S-9 single hop e skip like it wasn't there. whatever the wattage, there is a large yagi expelling the rf into the airwaves. on the other hand.....i have heard him 'in the mud', so 100kw is NO GUARANTEE of anything when there is competition, the BC stations are separated to make that happen has infrequently as possible. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 4793
Registered: 7-2004
| | Posted on Tuesday, February 02, 2010 - 3:45 pm: |
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http://www.g8wrb.org/data/Eimac/4CX5000A.pdf |
Kf4gyp
Junior Member
Username: Kf4gyp
Post Number: 17
Registered: 11-2009
| | Posted on Friday, February 05, 2010 - 3:19 pm: |
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Hats off to you Patzerozero
I do in fact now know that I intentionally left out the the tube number to see who would in fact know what that tube is. Yes I do Work in the b\c industry am in fact an engineer as well but truly did not know the cost involved. I work in the support side in electronics and not in the transmit side as much. Thanks for the info on this monster.
73 Ray/Hawk-Eye
DE KF4GYP
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