The LARCAN page and photo's

A case for the Larcan 1KW.

Now that I have some RF out, a case to provide some shieldng from EMR is a must but how to do it without making it the size of a telephone box. I had some scrap 2mm and 1.6mm Ali sheet on hand so a quick trip to a guilotine at my work place gave me two strips for the sides (1.6mm) and a strip for the rear (2mm). Now the height of the sides and rear were restricted by what was on hand at the time, I want to mount the RF change over relays (flat rectangular NARDA's) poking out of the rear panel.

So here is the Mark 1 rear panel and sides for my Larcan. I will use this first case to flesh out the design problems and then try an incorperate the output connector mod into the new rear panel.

Peter, June 2012

Mark 1 rear panel, fastening screws are 5mm Allen key head screws, into holes I have drilled and tapped.

Side panels are slid down between the heatsink and the mountin rails, then holes drilled in the sheet and the original screws passed through it, ends up with nice and strong mount.

Rear corner, will have ali angle bolted on the inside to join the two sections of sheet

Input connector can now be angled so the centre pin aligns with the PCB input track, which allows the original hole to be used to secure the rear panel.

Side view, output port coax needs to be removed and the coax passed through a new hole if you want to retain the monitor port.
On the otherside the green status light must be removed.

looking into the module towards the output connector, there will be a nice RF tight box once completed. Note clearance around the 50V busbar to prevent any 'splats'

October 2012, time to take another snapshot of progress

Have cut the holes for two NARDA 24volt relays.

I have used some 10x10mm ali angle to create a top lip for the box, this also give a structure to the top for a lid to sit on.

Have also replaced the original LARCAN front panel with a peice of aluminioum I had on hand, pretty well a perfect fit.

Jan 2013, its time to put this beast to air

Top cover is just sitting there to keep any RF out of the shack, its hard to believe that it is producing an easy 400W and is stable.
Input port (left side as you look at it in the photo) has been angled to align BNC centre pin with PCB track to reduce stray RF.
Green wire on left is earth to the HP switchmodes case. Black and white wire is PTT from the rig, thee are some left overs on the right side from the deleted output monitoring port

What would I change?

Given the chance to do the rear panel a second time, I would have opted to integrate the new output connector into the panel and not had the fidgety cutout for the earlier output connector mod, this would give better rigidity and a better RF seal. Other than that the side panels being held in place by the side rails works well and was simple to put in place along with the new front panlel made sense.

Feb 2013

New top cover is nibbled out and the holes covered with bronzed fly wire to give the RF deck a bit of air flow.
No fans yet on the heat sink

Mach 2013, here is the top cover for the amp, the holes in the lid were nibbled out by a drill powered nibbler, my corners are a bit rough so I will not be showing off any close up's of the lid :-)
The bronze fly wire is held in place with some light gauge aluminium bar and pop vivets, while there is no intention to force air cool the components section I want there to be a path for natural air flow that also kept the RF in its place (inside the case)

So the project is tantilisingly near to an end, now need to decide on a lid fastener method and mount some fans on the underside of the heatsink for those long digital QSO's after it is moved into the rack.
Maybe then I can move on to the Mark II version which uses different input and output combiners.

This is probably the image that will get me into trouble, this is full pelt into my BIRD 1KW dummy load. Before you get too excited its a PEP reading on a whistle but it does show the amount of head room the amplifier will give me running at my license limit. (1KW permit has been applied for, March 2013)

This web page was last edited on Sunday, 10th MArch 2013 by vk5pj