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Converting The Harris Platinum TV Amplifier For Use on Six Meters And A Discussion of Trends in Solid State Ham Power Amplifiers D. Hallidy K2DH 3/2012.

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Presentation on theme: "Converting The Harris Platinum TV Amplifier For Use on Six Meters And A Discussion of Trends in Solid State Ham Power Amplifiers D. Hallidy K2DH 3/2012."— Presentation transcript:

1 Converting The Harris Platinum TV Amplifier For Use on Six Meters And A Discussion of Trends in Solid State Ham Power Amplifiers D. Hallidy K2DH 3/2012

2 Background Solid State PAs for amateur use are nothing new- theyve been around for decades! Think of the units made by: Solid State PAs for amateur use are nothing new- theyve been around for decades! Think of the units made by: Mirage Mirage KLM KLM Tokyo Hi-Power Tokyo Hi-Power TeleTec TeleTec TE Systems TE Systems The thing about all of these is that they typically only produce modest power ( W is the typical maximum), are fairly low gain (10-12dB typical using bipolar transistors), and they arent cheap! The thing about all of these is that they typically only produce modest power ( W is the typical maximum), are fairly low gain (10-12dB typical using bipolar transistors), and they arent cheap! They were designed to provide more RF output power primarily for mobile VHF/UHF stations, running on 12vdc. So their power capabilities are limited. They were designed to provide more RF output power primarily for mobile VHF/UHF stations, running on 12vdc. So their power capabilities are limited.

3 Background Technology has advanced! Today, companies have developed LDMOS (Lateral Diffusion Metal Oxide Semiconductor) devices (LDMOS FETs). Technology has advanced! Today, companies have developed LDMOS (Lateral Diffusion Metal Oxide Semiconductor) devices (LDMOS FETs). High gain, can produce lots of power in small packages (20+dB Gain, Hundreds of Watts to >1kW typical power). High gain, can produce lots of power in small packages (20+dB Gain, Hundreds of Watts to >1kW typical power). Typically operate in the 50vdc range, making them impractical for mobile use, but just fine for home station RF power generation. Typically operate in the 50vdc range, making them impractical for mobile use, but just fine for home station RF power generation. Relatively cheap! Relatively cheap! Some companies (for example Ameritron) have designed products for the ham using LDMOS devices. The ALS-600 and ALS1300 are examples of 600 and 1300W solid state HF amps they offer. Some companies (for example Ameritron) have designed products for the ham using LDMOS devices. The ALS-600 and ALS1300 are examples of 600 and 1300W solid state HF amps they offer. Some hams have designed high power VHF/UHF amps using them, also. Well see examples and references to some of them in this presentation. Some hams have designed high power VHF/UHF amps using them, also. Well see examples and references to some of them in this presentation. Some high power commercial LDMOS amps have become available as surplus to the hams, too. This presentation is centered around one of these. Some high power commercial LDMOS amps have become available as surplus to the hams, too. This presentation is centered around one of these.

4 Background With the changeover to Digital TV, all broadcasters had to remove their VHF analog transmitters from service, to change over to digital transmitters. With the changeover to Digital TV, all broadcasters had to remove their VHF analog transmitters from service, to change over to digital transmitters. Many of these analog transmitters were built by Harris and were sold as the Platinum series of TV transmitters. Many of these analog transmitters were built by Harris and were sold as the Platinum series of TV transmitters. Transmitters ranged in output power from 20kW to 100kW, depending on how many 1kW modules were installed. Transmitters ranged in output power from 20kW to 100kW, depending on how many 1kW modules were installed. Very sophisticated units, designed for Hot-Swapping failed PA modules, with many levels of fault detection and protection built into them. Very sophisticated units, designed for Hot-Swapping failed PA modules, with many levels of fault detection and protection built into them. After these transmitters were pulled from service, some of the modules began appearing on the amateur surplus market, instead of in the dumpster. After these transmitters were pulled from service, some of the modules began appearing on the amateur surplus market, instead of in the dumpster. Two versions exist- low band (Ch 2-7) and high band (Ch8-13). Either can be converted for 6m operation, but the low band version is easiest. Two versions exist- low band (Ch 2-7) and high band (Ch8-13). Either can be converted for 6m operation, but the low band version is easiest. Modules were rated for 1kW video service, 24/7. Modules were rated for 1kW video service, 24/7. Will provide at or near legal limit output in amateur service with modest drive (~25W). Will provide at or near legal limit output in amateur service with modest drive (~25W). Here we will discuss the low band version of the Harris amp in amateur service. Here we will discuss the low band version of the Harris amp in amateur service.

5 Harris Amp Specs Each module consists of 16 Philips ON4402H LDMOS transistors connected in 4 pallets of 2 push-pull pairs each and combined. Each module consists of 16 Philips ON4402H LDMOS transistors connected in 4 pallets of 2 push-pull pairs each and combined. Operates on 50VDC (as do most of the LDMOS power transistors in use today), at about 45A (1500W output). Operates on 50VDC (as do most of the LDMOS power transistors in use today), at about 45A (1500W output). Drive for 1500W out is about 25W, well within range of common 6m equipment. Drive for 1500W out is about 25W, well within range of common 6m equipment.

6 Where Can I Get One? I got mine from Steve W1SMS at Microwave Update 2011 this past Fall. He may still have some; he got a quantity of them from WCBS (100kW transmitter) in NYC. I got mine from Steve W1SMS at Microwave Update 2011 this past Fall. He may still have some; he got a quantity of them from WCBS (100kW transmitter) in NYC. Lance W7GJ has been advertising them and still has some. Lance W7GJ has been advertising them and still has some. As far as I know, these are the low band versions only. As far as I know, these are the low band versions only.

7 Some Images of The Harris Platinum Amplifier Module Drawer front, used for inserting/removing the module in its chassis Fault/operate indicators BIG heatsink!

8 PAY ATTENTION!!!

9 Inside the module, showing the four pallets RF Output FET Switches to turn on amp

10 One pallet, showing all four devices

11 One Pair of ON4402H MOSFETS Image Courtesy KB3XG

12 Where Can I Find Modification Info? John Sortor KB3XG wrote an article (3 parts) in the Mt. Airy Pack-Rats Cheese Bits newsletter in May, June, and August This article is very complete and gives all the steps necessary to convert the low band unit to 6m. He also shows power output achieved, drive and DC power required, and quite a bit of operational data. He also discusses cooling at length- good cooling is a must, as none is provided in the module as it stands alone (cooling was part of the main Platinum chassis). He also discusses the power supply requirements, as well as the need for a high power low-pass filter on the RF output. John Sortor KB3XG wrote an article (3 parts) in the Mt. Airy Pack-Rats Cheese Bits newsletter in May, June, and August This article is very complete and gives all the steps necessary to convert the low band unit to 6m. He also shows power output achieved, drive and DC power required, and quite a bit of operational data. He also discusses cooling at length- good cooling is a must, as none is provided in the module as it stands alone (cooling was part of the main Platinum chassis). He also discusses the power supply requirements, as well as the need for a high power low-pass filter on the RF output. W7GJ has also written a very complete set of modification instructions. Lance even tells you how to combine two of them for as much as 2.5-3kW out! See the link to his website at the end of this presentation. W7GJ has also written a very complete set of modification instructions. Lance even tells you how to combine two of them for as much as 2.5-3kW out! See the link to his website at the end of this presentation.

13 Cooling The module does NOT include any cooling. Cooling air was provided inside the main chassis into which the modules were installed. Therefore, you must provide plenty of air to the heatsinks on the top of the module. The module does NOT include any cooling. Cooling air was provided inside the main chassis into which the modules were installed. Therefore, you must provide plenty of air to the heatsinks on the top of the module. From the various articles, it appears that 4-5 muffin fans above the heatsink will adequately cool the unit, but SUCKING air up from the heatsink, NOT blowing it onto the heatsink. From the various articles, it appears that 4-5 muffin fans above the heatsink will adequately cool the unit, but SUCKING air up from the heatsink, NOT blowing it onto the heatsink. This forces air past the entire heatsink, instead of cooling only the area below the fan (which can also cause a hot spot directly under the fan center). This forces air past the entire heatsink, instead of cooling only the area below the fan (which can also cause a hot spot directly under the fan center). KB3XG built a very nice plenum for his cooling fans that is probably overkill (see image). KB3XG built a very nice plenum for his cooling fans that is probably overkill (see image).

14 KB3XGs Cooling System Image courtesy KB3XG/PackRats End of unit where drawer front would be Plenum over heatsink, fans on the side Cable to fault/operate indicators

15 W7GJs Cooling system Images Courtesy W7GJ

16 Power Supply See the image on the next page. The amplifier requires 50VDC at nearly 50A. See the image on the next page. The amplifier requires 50VDC at nearly 50A. This sounds difficult (read: expensive), but its not. This sounds difficult (read: expensive), but its not. Blade Server power supplies are available on eBay for $38 (incl. shipping!) which are rated for 57A. These are switchers used in server applications, and are clean and well- regulated. They operate from Single Phase. They are new surplus, no junk, made by HP. The model number is BL20P. Blade Server power supplies are available on eBay for $38 (incl. shipping!) which are rated for 57A. These are switchers used in server applications, and are clean and well- regulated. They operate from Single Phase. They are new surplus, no junk, made by HP. The model number is BL20P.

17 HP/Compaq BL20P Blade Server Power Supply- 50V/57A

18

19 Hardware Modifications There are not many mods required- they are: There are not many mods required- they are: DC Power Connector DC Power Connector The original DC Power/RF Input/PTT Input connector should be removed and a haevy-duty Cinch-Jones screw-type terminal strip installed in its place for the DC power connections (see images). The original DC Power/RF Input/PTT Input connector should be removed and a haevy-duty Cinch-Jones screw-type terminal strip installed in its place for the DC power connections (see images). RF Input Connector RF Input Connector This was part of the power connector but a BNC or other small connector can be installed on the end of the chassis very easily (see image). This was part of the power connector but a BNC or other small connector can be installed on the end of the chassis very easily (see image). RF Output Connector RF Output Connector Since the unit was deigned for Hot-Swapping and instant plug in, the output connector is not a threaded type. However, it is the same size as a Type N and can be easily replaced with a chassis-mount N female connector which will solder right to the output directional coupler board (see images). Since the unit was deigned for Hot-Swapping and instant plug in, the output connector is not a threaded type. However, it is the same size as a Type N and can be easily replaced with a chassis-mount N female connector which will solder right to the output directional coupler board (see images). PTT Input Connection PTT Input Connection A ground on the violet wire in the original multi-function connector puts the unit in transmit. This wire can be brought out to an RCA jack or another terminal of the power connector. A ground on the violet wire in the original multi-function connector puts the unit in transmit. This wire can be brought out to an RCA jack or another terminal of the power connector.

20 Modified RF, DC, and PTT Input Images Courtesy KB3XG/PackRats

21 Added Type N Output Connector Images Courtesy KB3XG/PackRats

22 Expected Performance Again, it should be emphasized- these amps require no tuning for optimum performance on 6 meters. SOOOOO… Again, it should be emphasized- these amps require no tuning for optimum performance on 6 meters. SOOOOO… P in =26W; P out =1475W; I ds =43.7A; V ds =47.3V; Max temp=61.2 o C; Gain=17.5dB; Eff=71.4% P in =26W; P out =1475W; I ds =43.7A; V ds =47.3V; Max temp=61.2 o C; Gain=17.5dB; Eff=71.4% As you can see, these are pretty good numbers- and these were taken AFTER the low-pass filter was installed! As you can see, these are pretty good numbers- and these were taken AFTER the low-pass filter was installed! The performance numbers listed above are not mine, they are KB3XGs. My unit is still a work in progress, but should be complete by Spring. The performance numbers listed above are not mine, they are KB3XGs. My unit is still a work in progress, but should be complete by Spring. I highly recommend referring to both KB3XGs and W7GJs articles for details not presented here. I highly recommend referring to both KB3XGs and W7GJs articles for details not presented here.

23 What Other Choices Do I have? Theres another TV amp out there (Canadian) called the LARCAN. These were also pulled and made available; with careful searching you might find one- they are similar in power to the Harris amps. Theres another TV amp out there (Canadian) called the LARCAN. These were also pulled and made available; with careful searching you might find one- they are similar in power to the Harris amps. You can roll your own! This is not as ridiculous as it seems. There are LDMOS transistors out there that will do >1kW output from 1-600MHz (Freescale MRFE6VP1K25HR6) for about $200 and there are many articles and folks building them- see the links at the end of the presentation for more info. You can roll your own! This is not as ridiculous as it seems. There are LDMOS transistors out there that will do >1kW output from 1-600MHz (Freescale MRFE6VP1K25HR6) for about $200 and there are many articles and folks building them- see the links at the end of the presentation for more info.

24 Popular VHF+ Solid State Devices for High Power Use Freescale MRFE6VP1K25HR6 (1200W out/1-600MHz) Freescale MRFE6VP1K25HR6 (1200W out/1-600MHz) Articles and kits for both 50 and 144MHz 1kw+ amps using this device (DUBUS 4/2010 for F1JRD article). See W6PQL.com for his 144 and 222MHz 1kW amps using this device. Articles and kits for both 50 and 144MHz 1kw+ amps using this device (DUBUS 4/2010 for F1JRD article). See W6PQL.com for his 144 and 222MHz 1kW amps using this device. Freescale MRFE6VP5600H (500W out/1-600MHz) Freescale MRFE6VP5600H (500W out/1-600MHz) Article and kit for 432Mhz 1kW amp using 2x this device (DUBUS 1/2012 for F5FLN article). Article and kit for 432Mhz 1kW amp using 2x this device (DUBUS 1/2012 for F5FLN article). NXP BLF578XR (1200W out/1-500MHz) NXP BLF578XR (1200W out/1-500MHz) No article Ive found yet, but Im sure there is one, as the price is about the same as the Freescale part. No article Ive found yet, but Im sure there is one, as the price is about the same as the Freescale part.

25 F1JRDs 2m 1kW Amp

26 Sources of Info, Parts, Kits, Complete SSPAs


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