MiniTiouner Hardware version 2

[g8gtz]

In preparation for the arrival of the new Serit compatible PCBs this week - would have been here on Friday but I was down the pub when DHL tried to deliver them - I have shown the project some real love and updated the Wiki pages:

https://wiki.batc.tv/MiniTioune

In order to be clear which board we are talking about I have referred to them as version 1 (the original board which we all currently have and available before January 2017) and Version 2 Serit tuner only PCB available after May 2017.

To complicate matters further, the Serit tuners currently on order and due in the next week are different from the previous batch! See here for the details: https://wiki.batc.tv/Serit_tuner

Please feedback after you have read it all carefully if the wiki is unclear or incorrect.

We now need someone to spend time and update the software page!!

73
Noel - G8GTZ

[M0SKM]

Mr postman delivered my Serit tuner and PCB lunchtime; very simple to assemble and the new board is really good quality.

Tested the finished tuner at teatime with signals from G4CPE and got the same MER as I did on the earlier Sharp model.

There was only one minor problem which I have overcome. At first it was impossible to get the coax inner to go into the lower "F" connector; the upper one was easy.

Starting with very thin tinned copper wire I managed to gradually ease what was just a very tight socket. Two sizes of wire later I managed to open it out far enough to take the coax. It's still quite tight but I'm happy it will be OK.

Thanks to those involved.

73 Steve

[g0mjw]

Glad to see you having success Steve

As these arrive I need to point out the obvious, just in case. The DC-DC converter needs to be set to 3.7-4v output before its output is connected to the linear regulators. This is because these LDO regulators can only take about 6V. There is a zener to provide some protection but damage is still possible and worst case you could end up with whatever is on the input appearing at the output - i.e. 5.6V on the 3.3V and 1.2V rails.

There are two options, one is to set the correct converter voltage before its installed on the PCB, the other is to remember not to fit the jumper that connects it to the regulators - JP2, ALT 4V and set it up in commissioning. My memory isn't what it was so I always set it up first, before installing and re-check twice before installing the jumper.

I also tend to test all the rails before fitting the NIM. This is easy as you can probe the top of the RFCs.

If you don't use the DC-DC and run off a 5V supply, you may need to heatsink the regulators. With the DC-DC, the copper area on the board seems to be adequate. Obviously, don't connect a higher voltage supply to JP2.

Mike

[g8gtz]

Thanks Mike and well done Steve,

I've updated the wiki pages:

https://wiki.batc.tv/MiniTiouner_hardwa ... _schematic

73
Noel - G8GTZ

[G3UKV]

Starting to sort parts out for the Vers 2 PCB. Looking on eBay there are various DC-DC converters, but none look like the photos.
Can anyone advise an eBay item number for it, so that it will definitely fit the PCB please ?

[g0mjw]

There are now build notes on the Wiki

[M0SKM]

Starting to sort parts out for the Vers 2 PCB. Looking on eBay there are various DC-DC converters, but none look like the photos.
Can anyone advise an eBay item number for it, so that it will definitely fit the PCB please ?

These are the correct type.

161811570603

[g0mjw]

I used these 401012912499

Mike

[g0mjw]

I would be interested in reports on how sensitive the new tuners with built in LNA are, especially on 2m. All of the ones I have built to date have used the tuner without LNA. These are deaf, but that is to be expected!

Mike

[G8XZD-TV]

I know there is a digikey parts list on the wiki but does anyone have a Farnell parts list for the mk2 minitioune please?

73 ian