Whats your Work-Bench/lab look like? Post some pictures of your Lab.

[hamster_nz]

Here is a current photo of my electronics workbench.

This is only 1/8 of my shed, the rest of for other hobbies.

But did you win the 3D printer? (competition web page on your screen)

[Howardlong]

Here's a nerdgasm for y'all. Last night, getting some firmware working for a geostationary satellite due for launch at the end of the year. The first time I can remember actually really needing two spec ans at the same time.

[xrunner]

Here's a nerdgasm for y'all.

Oh oh oh ... 

[Richard Head]

Howard
Is that an analogue or digital transponder?
Dick

[Howardlong]

Howard
Is that an analogue or digital transponder?
Dick

Digital and real time regenerating, it's to do with normalising the passband from multiple uplinks.

[nctnico]

Do I spot a Red Pitaya?

[Richard Head]

Howard
I'm not sure what you mean by normalising the passband for different uplinks. Are you referring to the simultaneous strong/weak station AGC problem?
I designed and built an analogue transponder a few years ago and came head to head with the problem above. I considered multiple crystal filters to split up the passband each with their own AGC but it became a bit impractical. It was an interesting project which I may re-visit.

[Howardlong]

Howard
I'm not sure what you mean by normalising the passband for different uplinks. Are you referring to the simultaneous strong/weak station AGC problem?
I designed and built an analogue transponder a few years ago and came head to head with the problem above. I considered multiple crystal filters to split up the passband each with their own AGC but it became a bit impractical. It was an interesting project which I may re-visit.

Yes that is the application, multiple uplinks on a transponder and providing a channelised AGC by digitising the transponder passband, applying a dynamically calculated filter, then passing it back to the analogue domain for retransmission of a uniform passband on the downlink. It is complicated a little in this application as this is for a large number of narrowband uplinks with little frequency coordination, so the filtering is quite ganular. It also does a few other things such as a telemetry modulator and a concatenated block/interleaver/convolution FEC implementation.

[Richard Head]

Very interesting. Good luck with it. I hope you manage to get a launch soon.

[Howardlong]

Very interesting. Good luck with it. I hope you manage to get a launch soon.

It's based on some work I first published and demonstrated back in 2005(!) Coincidentally and separately at the time another group who I know well were also working on the same thing in the US: it was pretty much an obvious solution at the time to this problem as software defined radio had become well adopted by then. The concepts have been used since, but due to ITAR and the complexities of gaining a TAA for a non-US citizen at the time, I wasn't involved in the design or implementation of the first space deployment, other than to supply a low phase noise LO reference, hardly the most exciting part of the project!

The bit of the project from back then that I still want to deploy that's yet to find someone brave enough are the digitally controlled LINC and EER bits. We're still using standard TWTAs as on-board commodity parts.

[Richard Head]

Howard
I seem to remember reading some work done on a digital implementation of a linear transponder a few years ago. It may well have been yours. It's definitely the way to go. I wonder what the current consumption is like. Isn't the digital solution a little power hungry though?
My transponder was all analogue and I opted simply to run the PA in back-off to get the IMD products down. My output power was only +30dBm so efficiency wasn't too much of a concern.
For SSB anything better than -30dB below PEP is probably a waste of time and effort anyway.
I did briefly consider EER as per the Carl Meinzer AO7 implementation but the power saving wasn't worthwhile at my power level.   
For a while I did get fixated with getting the PA IMD way down but for analogue signals the reward/effort ratio isn't good.
Why are you using TWTAs and not SSPAs anyway? I believe SSPAs are being used at X-band already.

[Howardlong]

The EER is very loosely based on Karl's work on HELAPS but we added quite a few changes as this was working at much higher frequencies. I know Karl fairly well, I've met him at Marburg at his old facilities there and elsewhere over the years.

The choice of TWTAs was simply due to customer requirements and mitigating against risk of non-delivery on a very short delivery timescale. A wise desision IMHO given the requirements I'm aware of, but it doesn't stop the inner nerd wanting a platform to try out their stuff!

30dB is exactly the dynamic range of the passband that I work to by the way.

[Richard Head]

Howard
I dug through some articles that I had filed and found a relatively recent one of yours about a digital transponder using STELLA. It was very interesting but a little beyond me as far as the DSP is concerned.
The passband AGC shaping was interesting and only practical with brickwall DSP filters I suppose.
I had been racking my brain trying to come up with some sort of analogue anti-phase scheme to null out the offending strong signal, to no avail.

[Johnny10]

After looking at this pic I think I better get better organized.

[PA0PBZ]

After looking at this pic I think I better get better organized.

good to see that I'm not the only one with a DSA 

[Johnny10]

Although it is the size of a small refrigerator I love using my DSA 602.

What about you?

[med6753]

When I first joined the blog back in October 2015 my "bench" looked like this. I was just getting back into the hobby after many years of mostly inactive...


The latest. Still a work in progress but I've been getting equipment out of storage and fixed up and put back into service.


The laptop can easily be removed leaving a decent, but not huge, work area.

[AF6LJ]

Your bench is coming along really well.
 

[med6753]

Your bench is coming along really well.
 

Thanks. I forgot to mention that the bench is my own design and built from scratch about 20 years ago.

[Cubdriver]

Your bench is coming along really well.
 

Thanks. I forgot to mention that the bench is my own design and built from scratch about 20 years ago.

Nicely done!

-Pat

[med6753]

Your bench is coming along really well.
 

Thanks. I forgot to mention that the bench is my own design and built from scratch about 20 years ago.

Nicely done!

-Pat

Since the bench is in the living room when the mood strikes me I can close up the shelving to make it look more "presentable". But I generally leave it open. I don't have a permanent "She who must be obeyed" living here so I don't have to contend with that drama. But when she does visit she accepts it for what it is. And I must admit that she does make good suggestions about other aspects of my humble abode. But in the end it's my place and my rules. 

[Forser]

Here is my current workplace.

Waiting for my Scope (Rigol DS1054z).

[Addicted2AnalogTek]

Here is my current workplace.

Waiting for my Scope (Rigol DS1054z).

It seems that nearly everyone else starts out their labs with something that mine lacks... basic organizational things.   lol    most of my rather large part stash is housed in flat rate boxes!! ....At least I still know where everything is... for now.

[Howardlong]

Here is my current workplace.

Waiting for my Scope (Rigol DS1054z).

It seems that nearly everyone else starts out their labs with something that mine lacks... basic organizational things.   lol    most of my rather large part stash is housed in flat rate boxes!! ....At least I still know where everything is... for now.

My workspaces have always grown organically. Occasionally, maybe once every two or three years,  I'll decide to completely re-do it, strip it down completely, but invariably it's to no net benefit... and a day or two of lost productivity.

[PTR_1275]

A complete strip down and redo of my bench is going to happen over Easter. Too many additions since it was last reorganized that it is now going to take a completely fresh approach.

Hopefully the 4 days will be long enough to remove everything, clean, put everything back and wire the racks / bench. It's going to take a fair bit of planning before hand to see what layout of benches / tool chests / racks will work best.