Converting The Harris Converting The Harris Platinum TV Amplifier Platinum TV Amplifier For Use on Six MetersFor Use on Six Meters

And A Discussion of Trends in And A Discussion of Trends in Solid State Ham Power AmplifiersSolid State Ham Power Amplifiers

D. Hallidy K2DH 3/2012D. Hallidy K2DH 3/2012

BackgroundBackground

Solid State PA’s for amateur use are nothing new- they’ve been Solid State PA’s for amateur use are nothing new- they’ve been around for decades! Think of the units made by:around for decades! Think of the units made by: MirageMirage KLMKLM Tokyo Hi-PowerTokyo Hi-Power TeleTecTeleTec TE SystemsTE Systems

The thing about all of these is that they typically only produce modest The thing about all of these is that they typically only produce modest power (150-200W is the typical maximum), are fairly low gain (10-power (150-200W is the typical maximum), are fairly low gain (10-12dB typical using bipolar transistors), and they aren’t cheap!12dB typical using bipolar transistors), and they aren’t cheap!

They were designed to provide more RF output power primarily for They were designed to provide more RF output power primarily for mobile VHF/UHF stations, running on 12vdc. So their power mobile VHF/UHF stations, running on 12vdc. So their power capabilities are limited.capabilities are limited.

BackgroundBackground Technology has advanced! Today, companies have developed LDMOS Technology has advanced! Today, companies have developed LDMOS

(Lateral Diffusion Metal Oxide Semiconductor) devices (LDMOS FETs).(Lateral Diffusion Metal Oxide Semiconductor) devices (LDMOS FETs). High gain, can produce lots of power in small packages (20+dB Gain, High gain, can produce lots of power in small packages (20+dB Gain,

Hundreds of Watts to >1kW typical power).Hundreds of Watts to >1kW typical power). Typically operate in the 50vdc range, making them impractical for Typically operate in the 50vdc range, making them impractical for

mobile use, but just fine for home station RF power generation.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 Some companies (for example Ameritron) have designed products for the ham using LDMOS devices. The ALS-600 and ALS1300 are examples of ham using LDMOS devices. The ALS-600 and ALS1300 are examples of 600 and 1300W solid state HF amps they offer.600 and 1300W solid state HF amps they offer.

Some hams have designed high power VHF/UHF amps using them, also. Some hams have designed high power VHF/UHF amps using them, also. We’ll see examples and references to some of them in this presentation.We’ll see examples and references to some of them in this presentation.

Some high power commercial LDMOS amps have become available as Some high power commercial LDMOS amps have become available as surplus to the hams, too. This presentation is centered around one of surplus to the hams, too. This presentation is centered around one of these.these.

BackgroundBackground With the changeover to Digital TV, all broadcasters had to remove their VHF With the changeover to Digital TV, all broadcasters had to remove their VHF

analog transmitters from service, to change over to digital transmitters.analog transmitters from service, to change over to digital transmitters. Many of these analog transmitters were built by Harris and were sold as the Many of these analog transmitters were built by Harris and were sold as the

“Platinum” series of TV transmitters.“Platinum” series of TV transmitters. Transmitters ranged in output power from 20kW to 100kW, depending on how Transmitters ranged in output power from 20kW to 100kW, depending on how

many 1kW modules were installed.many 1kW modules were installed. Very sophisticated units, designed for “Hot-Swapping” failed PA modules, with Very sophisticated units, designed for “Hot-Swapping” failed PA modules, with

many levels of fault detection and protection built into them.many levels of fault detection and protection built into them. After these transmitters were pulled from service, some of the modules began After these transmitters were pulled from service, some of the modules began

appearing on the amateur surplus market, instead of in the dumpster. 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 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.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 Here we will discuss the low band version of the Harris amp in amateur service.service.

Harris Amp SpecsHarris Amp Specs Each module consists of 16 Philips Each module consists of 16 Philips

ON4402H LDMOS transistors connected ON4402H LDMOS transistors connected in 4 pallets of 2 push-pull pairs each and in 4 pallets of 2 push-pull pairs each and combined.combined.

Operates on 50VDC (as do most of the Operates on 50VDC (as do most of the LDMOS power transistors in use today), at LDMOS power transistors in use today), at about 45A (1500W output).about 45A (1500W output).

Drive for 1500W out is about 25W, well Drive for 1500W out is about 25W, well within range of common 6m equipment.within range of common 6m equipment.

Where Can I Get One?Where Can I Get One?

I got mine from Steve W1SMS at I got mine from Steve W1SMS at Microwave Update 2011 this past Fall. He Microwave Update 2011 this past Fall. He may still have some; he got a quantity of may still have some; he got a quantity of them from WCBS (100kW transmitter) in them from WCBS (100kW transmitter) in NYC.NYC.

Lance W7GJ has been advertising them Lance W7GJ has been advertising them and still has some.and still has some.

As far as I know, these are the low band As far as I know, these are the low band versions only.versions only.

Some Images of The Harris Some Images of The Harris Platinum Amplifier ModulePlatinum Amplifier Module

Drawer front, used forinserting/removing themodule in its chassis

Fault/operateindicators

BIG heatsink!

PAY ATTENTION!!!

Inside the module, showing the four pallets

RF Output

FETSwitchesto turnon amp

One pallet, showing all four devices

One Pair of ON4402H MOSFETSOne Pair of ON4402H MOSFETS

Image Courtesy KB3XG

Where Can I Find Modification Where Can I Find Modification Info?Info?

John Sortor KB3XG wrote an article (3 parts) in the Mt. John Sortor KB3XG wrote an article (3 parts) in the Mt. Airy Pack-Rats “Cheese Bits” newsletter in May, June, Airy Pack-Rats “Cheese Bits” newsletter in May, June, and August 2010. This article is very complete and gives and August 2010. This article is very complete and gives all the steps necessary to convert the low band unit to all the steps necessary to convert the low band unit to 6m. He also shows power output achieved, drive and DC 6m. He also shows power output achieved, drive and DC power required, and quite a bit of operational data. He power required, and quite a bit of operational data. He also discusses cooling at length- good cooling is a must, also discusses cooling at length- good cooling is a must, as none is provided in the module as it stands alone as none is provided in the module as it stands alone (cooling was part of the main Platinum chassis). He also (cooling was part of the main Platinum chassis). He also discusses the power supply requirements, as well as the discusses the power supply requirements, as well as the need for a high power low-pass filter on the RF output.need for a high power low-pass filter on the RF output.

W7GJ has also written a very complete set of W7GJ has also written a very complete set of modification instructions. Lance even tells you how to modification instructions. Lance even tells you how to combine two of them for as much as 2.5-3kW out! See combine two of them for as much as 2.5-3kW out! See the link to his website at the end of this presentation.the link to his website at the end of this presentation.

CoolingCooling

The module does NOT include any cooling. Cooling air The module does NOT include any cooling. Cooling air was provided inside the main chassis into which the was provided inside the main chassis into which the modules were installed. Therefore, you must provide modules were installed. Therefore, you must provide plenty of air to the heatsinks on the top of the module.plenty of air to the heatsinks on the top of the module.

From the various articles, it appears that 4-5 muffin fans From the various articles, it appears that 4-5 muffin fans above the heatsink will adequately cool the unit, but above the heatsink will adequately cool the unit, but SUCKING air up from the heatsink, NOT blowing it onto SUCKING air up from the heatsink, NOT blowing it onto the heatsink.the heatsink. This forces air past the entire heatsink, instead of cooling only the 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 area below the fan (which can also cause a hot spot directly under the fan center).the fan center).

KB3XG built a very nice plenum for his cooling fans that is KB3XG built a very nice plenum for his cooling fans that is probably overkill (see image).probably overkill (see image).

KB3XG’s Cooling SystemKB3XG’s Cooling System

Image courtesy KB3XG/PackRats

End of unitwhere “drawer”front would be

Plenum over heatsink, fans on the side

Cable to fault/operate indicators

W7GJ’s Cooling systemW7GJ’s Cooling system

Images Courtesy W7GJ

Power SupplyPower Supply

See the image on the next page. The amplifier See the image on the next page. The amplifier requires 50VDC at nearly 50A.requires 50VDC at nearly 50A.

This sounds difficult (read: expensive), but it’s This sounds difficult (read: expensive), but it’s not.not.

Blade Server power supplies are available on Blade Server power supplies are available on eBay for $38 (incl. shipping!) which are rated for eBay for $38 (incl. shipping!) which are rated for 50VDC @ 57A. These are switchers used in 50VDC @ 57A. These are switchers used in server applications, and are clean and well-server applications, and are clean and well-regulated. They operate from 240VAC @20A, regulated. They operate from 240VAC @20A, Single Phase. They are new surplus, no junk, Single Phase. They are new surplus, no junk, made by HP. The model number is BL20P.made by HP. The model number is BL20P.

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

Hardware ModificationsHardware Modifications There are not many mods required- they are:There are not many mods required- they are: DC Power ConnectorDC Power Connector

The original DC Power/RF Input/PTT Input connector should be The original DC Power/RF Input/PTT Input connector should be removed and a haevy-duty Cinch-Jones screw-type terminal strip removed and a haevy-duty Cinch-Jones screw-type terminal strip installed in its place for the DC power connections (see images).installed in its place for the DC power connections (see images).

RF Input ConnectorRF Input Connector This was part of the power connector but a BNC or other small 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 connector can be installed on the end of the chassis very easily (see image).image).

RF Output ConnectorRF Output Connector Since the unit was deigned for “Hot-Swapping” and instant plug in, the 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 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 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 connector which will solder right to the output directional coupler board (see images).(see images).

PTT Input ConnectionPTT Input Connection A ground on the violet wire in the original multi-function connector puts 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 the unit in transmit. This wire can be brought out to an RCA jack or another terminal of the power connector.another terminal of the power connector.

Modified RF, DC, and PTT InputModified RF, DC, and PTT Input

Images Courtesy KB3XG/PackRats

Added Type N Output ConnectorAdded Type N Output Connector

Images Courtesy KB3XG/PackRats

Expected PerformanceExpected Performance Again, it should be emphasized- these amps require no Again, it should be emphasized- these amps require no

tuning for optimum performance on 6 meters. tuning for optimum performance on 6 meters. SOOOOO…SOOOOO…

PPinin=26W; =26W; PPoutout=1475W=1475W; I; Idsds=43.7A; V=43.7A; Vdsds=47.3V; Max =47.3V; Max temp=61.2temp=61.2ooC; C; Gain=17.5dBGain=17.5dB; ; Eff=71.4%Eff=71.4%

As you can see, these are pretty good numbers- and As you can see, these are pretty good numbers- and these were taken AFTER the low-pass filter was installed!these were taken AFTER the low-pass filter was installed!

The performance numbers listed above are not mine, they The performance numbers listed above are not mine, they are KB3XG’s. My unit is still a “work in progress”, but are KB3XG’s. My unit is still a “work in progress”, but should be complete by Spring.should be complete by Spring.

I highly recommend referring to both KB3XG’s and I highly recommend referring to both KB3XG’s and W7GJ’s articles for details not presented here.W7GJ’s articles for details not presented here.

What Other Choices Do I have?What Other Choices Do I have?

There’s another TV amp out there (Canadian) There’s another TV amp out there (Canadian) called the LARCAN. These were also pulled called the LARCAN. These were also pulled and made available; with careful searching you and made available; with careful searching you might find one- they are similar in power to the might find one- they are similar in power to the Harris amps.Harris amps.

You can roll your own! This is not as ridiculous You can roll your own! This is not as ridiculous as it seems. There are LDMOS transistors out as it seems. There are LDMOS transistors out there that will do >1kW output from 1-600MHz there that will do >1kW output from 1-600MHz (Freescale MRFE6VP1K25HR6) for about $200 (Freescale MRFE6VP1K25HR6) for about $200 and there are many articles and folks building and there are many articles and folks building them- see the links at the end of the them- see the links at the end of the presentation for more info.presentation for more info.

Popular VHF+ Solid State Popular VHF+ Solid State Devices for High Power UseDevices 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 Articles and kits for both 50 and 144MHz 1kw+ amps

using this device (DUBUS 4/2010 for F1JRD article). using this device (DUBUS 4/2010 for F1JRD article). See W6PQL.com for his 144 and 222MHz 1kW amps See W6PQL.com for his 144 and 222MHz 1kW amps using this device.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 Article and kit for 432Mhz 1kW amp using 2x this

device (DUBUS 1/2012 for F5FLN article).device (DUBUS 1/2012 for F5FLN article). NXP BLF578XR (1200W out/1-500MHz)NXP BLF578XR (1200W out/1-500MHz)

No article I’ve found yet, but I’m sure there is one, as No article I’ve found yet, but I’m sure there is one, as the price is about the same as the Freescale part.the price is about the same as the Freescale part.

F1JRD’s 2m 1kW AmpF1JRD’s 2m 1kW Amp

Sources of Info, Parts, Kits, Sources of Info, Parts, Kits, Complete SSPA’sComplete SSPA’s

http://www.italab.comhttp://www.italab.com http://www.rfham.comhttp://www.rfham.com http://bigskyspaces.com/w7gj/HarrisAmps.htmhttp://bigskyspaces.com/w7gj/HarrisAmps.htm http://www.packratvhf.com/Cheese%20Bits/cheesebits.htmlhttp://www.packratvhf.com/Cheese%20Bits/cheesebits.html http://www.w6pql.comhttp://www.w6pql.com http://www.freescale.comhttp://www.freescale.com http://www.nxp.comhttp://www.nxp.com http://www.dubus.orghttp://www.dubus.org http://www.ad6iw.comhttp://www.ad6iw.com http://www.mmra.org/larcan/index.htmlhttp://www.mmra.org/larcan/index.html http://www.qsl.net/f1jrd/MRFE6VP1K25H.htmlhttp://www.qsl.net/f1jrd/MRFE6VP1K25H.html