We all know most government is low power but why comment here?

Allison
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Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting

Peter,

Where can I get info on the new QCX rig that is coming out probably later this year?  Is it possible it is a multi band unit?  I am just coming up to speed on my 20 meter QCX, but looking ahead.  Thanks,

Frank
WV4C

Fabulous insight Jim

 

My first visit was only back in the '80s but I’ve been there nearly every year since, sometimes more. I worked in music and more specifically flew one of those huge mixing consoles (SSL) that was mandatory in every recording studio back then. Like any complex bit of kit it had a huge manual but there were many ways to make it work for you that weren't written in there.

 

I honestly will never forget the look of horror of the Japanese assistant techs  as I "bent" the rules of operation, there was much manual page fumbling and protest but I managed to forge on citing translation difficulties.

 

That first session was a long project, 6 weeks I think so we got to know each other very well. By then I was reasonably world travelled but Tokyo was a utter culture shock. All of the Japanese involved in that project were so unbelievably hospitable and generous, way beyond anything I had ever known and it is a testament to the trust we built that I still remain friends with most from that first visit. Music still takes me back there most years but alas not this one for obvious reasons.

 

Those guys introduced me to a district of Tokyo around Akihabara Station in the Chiyoda ward of Tokyo. There is nothing you can do to prepare yourself for the onslaught of the visual and audio cacophony that awaits; there are certainly no words I can write here that will describe it but it has become a Mecca for me and I have made the pilgrimage on almost every visit. 

A visit here should be on every ham's bucket list, for underneath the railway arches by the station there is a labyrinth of corridors which hosts a mini market of EVERYTHING electronic. The pitches are arranged along one wall and are about 2 metres wide with the trader lurking in the shadows behind trays and trays of beautifully arranged components, the more successful have bigger areas but it is the presentation of the components on offer that is so breathtaking. If you have any old '60s radio that has lost a foot, you will find it here, 813 tetrode with a thoriated tungsten filament, no problem. Really they have everything, there was even an HRO there last November.

 

I know of one other regular poster on this forum that knows this area rather well J

 

73s Ted
2E0THH

It is probably a bad idea to seperate the PA transistors (IRF510) too far from the circuit board. Since they are trying to work together in a push-pull arrangement to drive a few amps of RF current through a transformer at high frequencies you are going to run in to all sorts of problems that will not be easy to predict or replicate for each different installation. 

Determining if the heat sink is sufficient requires quite a few data-points;

1. Power level you will be running at
2. Band you will be operating on
3. SWR that the amplifier sees from the antenna system
4. DC supply voltage and current
5. Duty cycle of the transmitter and mode of operation
6. Type of heat sink (aluminum finned, copper, just a steel plate)
7. Acceptable temperature rise of the PA
8. Thermal conductivity of the junction between the PA and heat sink
9. Convection cooled heat sink or forced air
....

You can see why many designers will put some margin in heat sink selection or incorporate devices to measure temperature at the PA to fold back the power or put the amplifier in to protection mode to prevent the magic smoke packets from being released.
--
Tisha Hayes, AA4HA
Sr Engineer, 4RF Inc.

Yes, Hans, I also see potential for your stalagmites not meeting my stalactites :-D

On a different note, will the enclosure have a pair of folding feet under the front? I want to avoid getting a stiff neck in the field… (not the US police kind of stiff neck, though.)

Here is the Wondom BCPB2 3S 18650 MPPT BMS I am talking about. Leaving out the DC connector, it is still 31.5 mm high with the electrolytic capacitors being the next highest components. However, if necessary, 1 mm can still be shaved off by replacing the 18650 cell holders.

It is pretty cheap, to the point that you perhaps could integrate it with your transceiver by default. The MPPT allows it to be used with a 18 to 24 V solar panel.

I got the idea of a video from Gil, F4WBY. He also employs this to supply power to his QCX radios. (Do not follow his suggestion of soldering directly to the cell terminals, though. Just apply once external power to the board to get it running.)

The newer version PCBs have extra headers to drive external power level LEDs, without the need to add any extra series resistors.