Fuse rating

[M0YDH]

Hello all
I can see in the pictures on the Wiki of Colin G6KLB's Portsdown that there is a fuse holder. I would like to add this wise precaution and wonder what supply current measurements have been made? What fuse do lead builders recommend?
I've read in another post about 2 and 3 amps being drawn. I'm still waiting for the DC-DC converter noted in another post to arrive. Yesterday in testing I ran the Pi from a 7805 regulator where the heat sink was bolted to the back panel. It had 5.08V across it no load and did standby ok. A lot of heat was going into the case. No use on transmit via a 500mm long cable. I'll revert to using the best android phone charger I have. That did well on transmit. No triumphs yet on receiving video. All magic smoke is still inside. Milliwatt meter and dummy load from my QRP labs U3S transmitter set will be used next.
All the best
David M0YDH

[g0mgx]

I suppose it depends on the efficiency or otherwise of your power supply electronics.

I've gone for linear regulators in mine fed from a conventional shack 13.8V PSU and the current draw on TX is about 1.3A so a 2A fuse seemed about on the money.

Mark
G0MGX

[g0mjw]

I'm using a 1A fuse as the draw from 12V is well under 1A. I have a DC-DC converter supplying the 5V for the PI. The filter board is running off 12V and takes about 250mA. So far its been fine, even with a capture dongle and the PICAM plugged in sending at 4Ms.

Mike

[M0YDH]

Thanks for that. I'll use a 2A quick blow fuse for now.
Is there a topic for "No RF out in IQ mode" yet? Pictured is the state of the build. I'm one resistor short on the RF switch. I can spend the next sessions going through the FM board commisioning steps found on the Wiki. The 71MHz output lends itself to use with my 100MHz oscilloscope.

Cheers
David M0YDH

[G8GKQ]

David

Some things to look at:

Do both lights on the ADF4351 board come on when you go to transmit in IQ mode?

When you transmit in carrier mode, can you hear the carrier on an SSB or FM receiver?

What is the current drain of the filter-modulator board?

Have you checked the RF power at the input and output of the f-m board?

Dave, G8GKQ

[g0mjw]

Hi Dave,

Did you set the reference frequency for the synth Board? Mine is 10MHz but the default is 25MHz. When I did a factory reset the reference was reset. It won't work until you set this correctly.

Mike

[g8gtz]

Hi David,

Looking closely at the picture, you only have 1 LED lit on the ADF4351 board - there should be 2 and it won't work until there is. The power LED is on but the lock light is not (just to left above the ref osc can in your picture). Edit by G8GKQ: the second (lock) LED will only come on when you go to transmit.

As Mike says the first thing to check is what is your ref osc frequency - should be written on the can or the ebay advert - and then check what is set in the "Advanced System Setup Menu" matches that. There's a full list of commands on this page - https://wiki.batc.tv/Console_mode

If still no joy, check your wiring between the ADF board and the GPIO breakout. Once the light is lit (you will need to reboot each time as the data is only loaded at switch on or freq change) you should be able to hear it in carrier mode on your normal FM rig.

Hope this helps.

Noel

[M0YDH]

Thank you very much to Noel, Dave and Mark
The 25MHz crystal on the signal source matched the settings in software.
No signal lock (D3) diode came on in transmit. In fact I'd never seen this LED before so there's a clue. I undid the ADF 4351 board and checked continuity from the bottom of the board back to the GPIO pins. All fine.

The break through came when I measured the voltage across the ADF 4351 expecting 8V [the no load voltage off my little voltage regulator board] and found 2.3V! Dave said that it might not work at 5V in another post and it definitely doesn't work at 2.3V! I tried for 8V off a 9V regualtor and potential divider which was pants. I connected the ADF4351 to 9V regulated direct and everything works! Simple with help from the experts. Lots of lovely carrier noises on 437.000 FM too.

Pictured is 71MHz out into a QRP power meter per G0UPL website http://www.hanssummers.com/powermeter. This showed output at 2m and zero at 70cm where I suspect the frequency was too great for the diode circuit. It showed high SWR at 437 FM on the FT817. The 1 watt at division 7 is good to 29MHz on the FT817ND rig [otherwise I have 0.17W].

I can now post in success stories.
Many thanks all
David