What's on your Workbench?

General discussion - When it doesn't fit anywhere else
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VK1JA
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Re: What's on your Workbench?

Post by VK1JA » Thu Nov 21, 2019 12:46 pm

VK2XAX wrote:
Thu Nov 21, 2019 4:21 am
Hi Jayson,

Where did you get the tin box and copper heat spreader from ?

I have a couple of Henning's boards and the parts but have yet to acquire the spreader etc.

thanks
Tim
G'day Tim,

The tin box came with the boards directly from Henning (DF9IC), while the copper heat spreader is from G4dbn. I can't remember the cost for the heat spreader, but it was quite reasonable, BUT I bought one that didn't have the holes drilled/tapped. And I found that drilling and tapping 12mm thick copper plate with hand tools isn't easy! If you have the option just buy the pre-drilled/tapped version....

http://www.g4dbn.uk/?p=763

By the way - some words from Henning regarding the large (2w) resistor feeding the bias, and on how to tune the PA -

"value not criticial, depends also on the voltage you want to apply there for bias. I use 470 Ohm / 2 W which works for both 12 and 28 V. The 5 V Zener must reach its voltage, with 2 x 1k load from the pots (plus a bit more from the 2k2 at the gates). For 12 V a value of 470 Ohm is minimum, for 28 V you can go up to 2k2. The required gate voltage for about 0.5....1 A bias current should be a bit more than 3 V.

For the tuning process it is enough to disconnect the drain voltage of the unused transistor. Start with 5 W drive, tune one transistor (expect 50....70 W at the output), same for the second, then connect both and you should be close to 250 W, you may try fine optimization. Each transistor should be driven to 10 A @ 28 V. I test each pallet up to 32 V, and use mine with 30 V supply
."

It's also a good idea to use a circulator on the input of the PA to protect your transceiver when you're tuning the PA!

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VK4EA
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Re: What's on your Workbench?

Post by VK4EA » Thu Nov 21, 2019 12:59 pm

24 GHz portable setup nearing completion. Not a record setting assembly but hopefully it will a lot easier to point compared to the 600 mm dish.



ImageImageImage


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Peter
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VK2XAX
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Re: What's on your Workbench?

Post by VK2XAX » Thu Nov 21, 2019 1:06 pm

VK1JA wrote:
Thu Nov 21, 2019 12:46 pm


The tin box came with the boards directly from Henning (DF9IC), while the copper heat spreader is from G4dbn.
Ahhh ignore my comment in PM about the box - I should have asked Henning for that when I bought mine.

thanks

Tim
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VK2XAX :: QF56if23 :: BMARC :: WIA :: AMSAT-VK

VK2XAX
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Re: What's on your Workbench?

Post by VK2XAX » Thu Nov 21, 2019 1:17 pm

VK4EA wrote:
Thu Nov 21, 2019 12:59 pm
24 GHz portable setup nearing completion.
Nice PA, what do that come out of ?
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VK2XAX :: QF56if23 :: BMARC :: WIA :: AMSAT-VK

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VK4EA
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Re: What's on your Workbench?

Post by VK4EA » Thu Nov 21, 2019 2:33 pm

VK2XAX wrote:
VK4EA wrote:
Thu Nov 21, 2019 12:59 pm
24 GHz portable setup nearing completion.
Nice PA, what do that come out of ?

http://www.i3opw.it/


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Peter
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VK4GHZ
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Re: What's on your Workbench?

Post by VK4GHZ » Fri Nov 29, 2019 2:44 pm

Acceptance testing a bunch of CAN bus adapter boards, which are then fitted to VK4GHZ Eltek Touchscreen Controller system boards.

20191129_142834_900.jpg

20191129_143051_900.jpg

http://vk4ghz.com/product/eltek-flatpack-2-controller/

Image

:beer:
Adam, Brisbane
http://vk4ghz.com | VK4GHZ on Youtube
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Re: What's on your Workbench?

Post by VK4GHZ » Sun Dec 01, 2019 12:32 pm

Too big (and dusty) for the workbench, but a faulty on/off power switch was fixed in an Electrolux ZUF4205AF vacuum cleaner.

These things are damn awkward to get apart!

Image

The "power" switch was actually a small tactile push button, no doubt feeding a microcontroller.

Full details documented here that should be discoverable by others over time:
http://vk4ghz.com/fixing-electrolux-zuf ... er-switch/

A $0.95 drop in replacement tactile switch was obtained from Jaycar.
Fixed in an hour, and I wasn't about to throw away a $600 vacuum cleaner like a Mr Joe disposable Public might.
Adam, Brisbane
http://vk4ghz.com | VK4GHZ on Youtube
10 things that happen when you stop checking Facebook constantly: http://tiny.cc/t5h7cz
Facebook use and mental health issues: https://tinyurl.com/twscvpp

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