144 Mhz home brew 600W solid state PA

[VK4DD]

Hi All,

I have just posted some new pictures and news for the Mark II board here.
The 90 degrees combiners have arrived! I got them already, so no 3 months delay.
I got them now.. see

http://www.vk4dd.com/forum/viewtopic.php?f=4&t=10

I also noticed that Jim W6PQL has added an other PCB which is can be used for this amplifier project.
He has got an alternative for the solid state switches we have been buying from Jaycar.
The PCB has a kill input (from protection) and it has a on input... use full from sequencing board.

http://www.w6pql.com/high_current_solid ... switch.htm

I think this PCB can be used to switch on the power to the BLF248 PA.
I link the bias wire to the +28V and switch the power on and off to the PA.
The kill input can be used if a signal from the protection needs to shut down the PA.

Thanks Jim for bringing out a this nice kit for us.
73

Ron
VK4DD

[VK4DD]

Hi Gents,

Looks like we are going to have a Redtech pretty soon. I am one of the speakers
And if you life in the Brisbane area you won't have to get on the plane either..

Ron VK4DD is coming to Redcliffe and District Radio Club on Monday 29th June 7.30pm he is speaking on VHF Amplifier Construction, it will be a very informative evening all welcome
Contact Information
Contact: David Close
Location: Klinger Rd.Kippering, McFarlane Park
Redcliffe, QLD 4035
Australia
Telephone: 610738628700
E-Mail: David_Close1@bigpond.com

73 Ron
VK4DD

[VK3XIL]

Hi

I have posted in the parts thread about a cheap source of Phillips BLF248 ands BLF177 that I intend to order at the end of the week.
If you want some, let me know.

cheers

Matt
VK3XIL

[VK4DD]

Good work Matt,

I like the new price of the BLF248 US$ 50 plus some import costs.

Matt is importing 1 or 2 and ships one to me. I will drop it in my test PA and see if it works.
Even if it is a Chinese replica, the main thing is that the FET works.
It is up to the user if you pay 150 or 50.

lower prices on 35 Ohm coax here. I think that is about half price of what we pay now...

http://www.vk4dd.com/forum/viewtopic.php?f=4&t=17



Cheers
Ron
VK4DD

[VK4DD]

Hi Gents,

News from Jim W6PQL.

I have been talking to Jim about the amplifier protection PCB for some time now, that may have contributed to the release of a new amplifier protection PCB.
The big advantage is that if the VSWR peaks, that it locks out the Amp. While the old board just temporary reduced the bias and kept transmitting.

Resetting the lock-out can be done a couple of ways; the easiest is to cycle the power off for a second or two. An alternate method is to use a momentary-contact pushbutton switch connected from the cathode of the red LED to ground.

Other than that Jim has improved the board with a stronger voltage regulator, extra leds for the front panel.
All in all a very nice product to go along with the BLF248 amps.

Jim is now also developing solid state modules to cut out the voltage.
More solid state modules are being developed by Jim also for 48V (which is handy for 48V based amps)
These will be on his site in 3 weeks or so.

Pricing US$ 35 for a kit or US$ 50 for a build one (via Jim W6PQL).

http://www.w6pql.com/Upgraded_Amplifier_Controller.htm

73 Ron
VK4DD

[VK4DD]

Hi Gents,

A single BLF248 is going crazy in my new MKII board.
Did the bird meter hit the 500W mark.....?

Don't do this...as it is way above factory specs.
But it shows that the "horse" wants to work in the MKII boards.
Horse power ... , horses for .....

watch the video here...
http://www.youtube.com/watch?v=F3uVRtSIDec

Cheers
Ron
VK4DD

[VK4DD]

Hi Gents,

Here is also an update about the previous posting... the Bird meter hit indeed the 500W mark.
But this meter is 10% out of tolerance in my opinion. As such we only got 450W out of the BLF248.
Max power will depend on how good the BLF248 is and if you can tweak the last watt out of the PCB.

I produced a new BLF248 PCB. It has the same input and output circuit as the double BLF248 PCB called the MKII.
The dimensions of this PCB and the place where the BLF248 is mounted is exactly the same as the first revision.
I don't know a good name for this PCB, but what about BLF248 REV2.
The artwork of the input and output are a copy of the MKII PCB.

It will need the same tuning caps as in the schematic as the BLF248 MKII.
It is basically the second generation BLF248 amp, with higher efficiency, and more output power.
Which means your amp will run cooler at the same power output.

They will be on my site for US$ 30 per PCB.
You can upgrade for US$ 20, if you destroy the old PCB's.
Please contact me via email if you wish to upgrade.

73 Ron
VK4DD

[VK5APN]

G'day

Ron has certainly made high power on 2m (and other bands) obtainable.

All of his amps require a copper heat spreader that is at least 6mm thick.

Not many suppliers stock 6mm copper plate. However I have located a local supplier for this copper.

This copper is labelled as "high cut copper". Which has a 0.4% sulphur content. This is machine gradeable copper. As any of you that has tried to drill or mill pure copper, it is like drilling into mud. This on the other hand is like working with brass. Much easier, but much more expensive than ordinary copper.

The copper comes in a bar that is 6 inches (152.4mm) wide and 1/4 inches (6.35mm) thick.

This supplier was used for the MK1 boards. Some 26 plates were obtained. As such can obtain bulk prices. These prices including shipping is cheaper than individual buys and pickup by a long way. The supplier continues to offer this bulk price on 10 or more plates.

The sizes (fixed dimensions are 152.4mm wide and 6.35mm thick, just the length changes) and prices (AUD $) for the different Amp PCB's are as follows:

BLF248 MK1 92mm at $25.00
BLF248 MK2 182mm at $53.00
BLF278 200mm at $59.00 (this will provide 2 plates - will need to be cut length wise)
HF Amps 120mm at $35.00

Local post and package is in the order of $15.00 depending on quantity ordered.

Within the next fortnight I will be picking up another batch of copper. So if you are interested then let me know, otherwise will have to wait until another 10 plates are on order. vk5apn@aapt"dot"net"dot"au. I think you know what to do with the "dot".

All those who have ordered will be receiving an email stating total price (including shipping) and payment methods.

Regards

Wayne

[VK4DD]

Hi Gents,

Indeed this "machine grade" copper from Wayne is very easy to tap and drill.
Karl VK2GKA commented the same to me, as he got the same copper heat spreader because we had one left over.
Very easy to tap and drill. It is almost of the copper is greased or so.
Normal copper feels like drilling in "mud". If you push hard you see a big dent in the copper next to the drill

Lets have a look what is on offer for the BLF project ...

Copper from VK5 (Wayne VK5APN) (see previous posting)
BLF's from VK3XIL (MATT) viewtopic.php?f=22&t=8601
PCB's from VK4 (me) http://www.vk4dd.com
and 35 Ohm via Germany http://www.vk4dd.com/forum/viewtopic.php?f=4&t=17
And lots of other hams not mentioned but helping with this project in various ways.

Hey there was even an interview from radio PI4AA for the broadcast next week or so.
http://www.pi4aa.nl/
So very soon you can hear me talking about this project in Europe.

Cheers
Ron
VK4DD

[VK4DD]

Hi Gents,

I hoped this moment would never come...
But I just got an email from a home brewer in PA land.
A BLF248 has died even before it got into service.
No bias current, no current at all. Dead as a dodo...
He did not look into ESD measures and as a result the FET is dead.
Touched the gates and drains with his fingers etc etc. (I touch only the porcelain case, or if needed only the flange! )

Let this be a reminder to all that these FETS are sensitive to static electricity.
You need to use proper solder gear, wear the anti static arm thing etc etc.
Use a solder Iron which is safe.

I have bended the legs of a FET once. I will never do it again.
Too risky, and not good for my blood pressure too.
I know it is posted in this forum, as we gathered information about this topic.
I DON'T DO IT. I also use normal 60/40 rather than the high melting point solder.
The high melting point solder is not good. You can hardly move them after wards.

YOU need protection for the BLF248 in my opinion.
The VSWR 50:1 is for a short time only. Believe me you don't want to find out how long or short that time is.
Make sure you got it. Also this is with a heat sink at 20 degrees, and certainly not a cooked FET.

READ THE POSTINGS that will save you from a lot of trouble even money...

Let this be a reminder to use the proper tools and read the postings.

I have also uploaded my guide lines (see attachment).

73 Ron
VK4DD

[VK5APN]

Copper Statistics

G'day all

I have just picked up the copper from the supplier today.

Total weight was 46.5kg. Total linear length was 5370mm. Enough to put your back out.

Plenty of Amps being built, especially in VK3.

There is a shipment of copper going to Gippstech this weekend. Thanks heaps to the kind person doing this for me and for the recipient/s.

There is VERY little copper left at the suppliers (900mm). Once it has gone, they will not re-order this (suppliers words).

If you would like some copper then email me your requirements etc. See previous postings for details.

Looks like there will be quite a few soldering irons working overtime in the construction phase.

Regards

Wayne VK5APN

[VK2FRO]

Hi folks!

Wow what a project, and its moved to mkII as I have been following all 11 pages of the project.

I've finally taken up some smd soldering and find it rather easy (I thought my eyesight wasnt that great, but using a magnifier lamp, its dead easy).

Those amp boards look awesome - love the blue colour of the mkII, and they look like a professional piece of gear even without components mounted.

I'm going to put together a MKII board. Since copper for the heat spreader is in shorter supply than the PCB's, I think I will start with that piece first, so i'll contact the previous poster and get the size required for 2 of the MKII boards. I will be building two amps, one for myself and one for a friend. The friends amp will sit on my shelf until he upgrades to advanced (from foundation).

The help and idea you fella's have organised for one another has really made this project come together. I happened across the project while looking for of all things, 2 metre yagi's!

edit: had demand instead of supply in regard to the copper

Cheers
Ben (now VK2FRO)

[VK5APN]

Copper

All

I have had more interest in copper.

With all orders being met (just), there remains NO MORE COPPER at the suppliers.

I am unsure if the supplier will be restocking this. However never say never. I'm sure if there is a lot of interest and a BIG order is in play, then they may. I am picking up the last of the copper today or Monday (have not heard from them saying it is ready to collect) and I will ask them regarding this.

I am happy for all those who have obtained copper, but saddened that future amp builders will have to be more resourceful.

Ron VK4DD does have some spare copper for the single BLF248 PCB's. You may like to try him if you are in need of some.

Statistics
Total length of copper in all orders was 9185mm. Of which 395mm was used for cutting giving individual copper plates total length of 8790mm.

I will post information here if there is a chance to buy more copper.

Regards

Wayne

[VK3XIL]

Hi

people might try recyclers and metal dealers
you are looking for copper electrical bus bar material
I have found this in the past (yeas ago)
usually pay by the kilo

cheers

[VK2FRO]

Wayne,

Pleased I got in with my request when I did - at least I will be able to start construction of an amp soon. Next up, ordering the PCB's

Cheers
Ben (Now VK2FRO)

[VK5APN]

Copper

Picked up the last lot tonight on the way home from work.

Asked and they said that they have copper in 6mm but it is a different alloy. Not like the nice stuff in the past that was machine grade copper. So maybe interesting to drill and tap etc.

The 6mm stuff comes in a bigger size (almost sheet size) and can be cut to what ever length and width that you want.

SO

If anyone is interested in this 6mm normal alloy copper, then let me know. I will do my best to negotiate a good price. Especially since we bought so much in the past. I have no idea on cost, but if enough interest then I will find out.

Regards

Wayne VK5APN

[VK4DD]

Hi Gents,

Great to see so much home brew activity ... all these copper heat spreader show that we Hams can do more than plug in connectors.
Any way we are now past the 6000 hits on this very popular topic. We are now heading for the 7000 hits.
Usually every 1000 hits there is some thing new.... this time it is the GLCD. This is a graphic display which now replaced the standard LCD display.

On the back of the GLCD we have made a piggy back PCB which communicates with the GLCD display.
A GLCD is too complicated to control via a PICAXE, so that is why we have chosen to use this translater board which controls the GLCD.
This translator PCB is called the GLCD piggy back board. And it takes care of the clock and the communication between the GLCD and the Picaxe.
So all the PICAXE has to do is collect the data and send it over to this PCB.
From there this PCB takes care of the communication with the display.

Want to know more about it?
Take a look here.
http://www.vk4dd.com/forum/viewtopic.ph ... p=108#p108

(note the Piggy back PCB is not ready, we are waiting for the CPU to arrive.
The picture of the working display is one taken from our development Board).

I also asked Wayne to send me some extra copper.
Just to make sure every one has got the copper they need.
As such I might be able to help a few Hams with the old VK5APN copper for a short time.
(copper size for 90 x 150,for single BLF248 boards)

73 Ron
VK4DD

[VK4DD]

Hi Gents,

Good news... PE2VAV is now up and running with a single BLF248 and reports 400W out.
http://www.vk4dd.com/forum/viewtopic.p ... 7&start=22

As far as the GLCD some progress has been made with the construction.
The more work we do on this project the better it looks.
When we started Patrick had to talk me into this project, because I though... hey this is just going to be an other display. But the power of this processor is huge.

There are also plans to connect a similar display to the K3 to display frequency, power etc. All we have to do is change the software....
As far as the PCB concerned and the display no changes have to be made.
If we want to communicate with the K3 (an HF/VHF radio) than all we have to do is send some commands to the serial port of the K3 and capture the response and send it to the display. Our CPU runs on 40 Mhz and we can even communicate at 115200 baud with on a serial link if we have to
So lets see how we go there.. it sound like an other interesting project.

We can also make an alarm clock out of this display, and comms board combination. Sounds like great fun.

The code is written with a swordfish compiler. If you want to do similar things.
Just co and get your self a compiler for a PIC18F2525.
And a programmer (you can buy one for US50 including shipping from China).

But for our amplifier application we will sell you a programmed PIC18F2525.
The only thing you can change is the program in the picaxe.
That will enable you to make some changes, like scaling, values etc.
But not the layout of the menu in display.

73 Ron
VK4DD

[VK4DD]

Hi Gents,

The chips arrived on Monday (2 days ago)
The GLCD PCB is working... we have contact with the time chip DS1307 and the time is displaying in Zulu Time
Nice Big fonts are used to display the power and SWR. In the top corner the time is displayed.
A back up battery keeps the clock ticking even when the amp is powered off.
Other pages with more info displayed more compact are also prepared.

No mistakes what so ever the PCB is perfect. I love it when things just want to work for the first time.

Any way the software is going well... especially if you consider that 2 days ago we had to start writing the code.
At the moment our GLCD is consuming 100mA and the voltage regulator runs cool.

O yes... it is bloody fast too.
One more thing. We have developed Icons.
You can see a standby symbol (same as the one on the TV remote control)
The circles Icon( the second) means we are transmitting.
The third one (a little bell) that is an alarm.
A high temperature Icon etc.

There will be several pages with info, or different display modes.
Showing volts, amps etc.

So far so good.... to be continued.

Well done Patrick

73 Ron
VK4DD

[VK3XIL]

This is SENSATIONAL

well done