One Last FM Exciter.

[radium98]

i wish if it was 4 watts 2n3866 2sc1947 or mrf237 alll in one plate , is true 1w . did you made a prototype . pira bw combination ?

[Zozo]

i wish if it was 4 watts 2n3866 2sc1947 or mrf237 alll in one plate , is true 1w . did you made a prototype .

I suppose 4 watts might have been nice for driver. I have tested both the Pira PLL and Broadcast Warehouse RF Strip together a long time ago, and they work very well with each other. This wasn't all done on a nice PCB though, but on copper clad. But I will be ordering the first sample board for testing.

[Bton-FM]

Why don't you redo the RF section's layout to make it more efficient? Having all those resistors in a neat line looks pretty, but it means that the tracks between each component are going to be longer. Especially the Oscillator coil - That's miles away from the the oscillator transistor!

Completely agree. I see a lot of boards designed like this and it pains me.

It seems Broadcast Warehouse got a graphic designer to do the layout rather than an engineer!

Does anyone know who did the BW exciter layout?

[Zozo]

Why don't you redo the RF section's layout to make it more efficient? Having all those resistors in a neat line looks pretty, but it means that the tracks between each component are going to be longer. Especially the Oscillator coil - That's miles away from the the oscillator transistor!

Completely agree. I see a lot of boards designed like this and it pains me.

It seems Broadcast Warehouse got a graphic designer to do the layout rather than an engineer!

Does anyone know who did the BW exciter layout?

A man after no own heart. Was equally passionate with elegance, as to functionality. I can think of many individuals with the same obsessive credo. To give credit where credit is due, there was nothing wrong with those designs, and I'm pretty sure they all had engineering degrees, in the R'n'D / manufacturing areas of the company.

Thinking back to to early days when discrete components dominated 99% of most RF designs, which was somewhat eccentric in the PCB track routing, they all still worked. If it was good enough for Yaesu, Kenwood and Icom etc. I think it's good enough for a small little one time project FM driver board.

[Zozo]

Talking of which, my own obsessives have been running in overtime. The last iteration of the board now with all though-holes.

BCWPIRARDY2.JPG

EDIT I did a JCL mock up in black, and it looked pretty good I thought

[Albert H]

Where are you going to get a 57kΩ resistor? You've got one in your oscillator stage!

[Zozo]

Your right, that's either 1 of 3 things. Firstly I made a type-o with the copying over from paper to computer some time ago. Secondly it's a deliberate Easter Egg planted to confuse copiers, which has made it's way over. Or finally it's a missing decimal point, but I don't recall there being a 5k7 resister?

I'll have to double check and possibly knock up the whole RF strip on clad to check.

On another note, I was toying with the idea of perhaps swapping out the fixed load capacitor for the crystal with a small variable instead. Be nice to have the ability to correct for crystal aging etc. Plus I'm OCD and like to see all zeros on the counter.

Work in progress

[nrg-uk]

57K should be 33K

[Zozo]

57K should be 33K

Thanks, I was this week going to put the RF strip on clad for a test anyway to be 100% sure. Anyhow I've done some revisions and this where I'm at.

Final2.JPG

[Zozo]

The PLL now has a new locking table as I've changed the RB Lines around for neatness

PLL Locking Table.png

[teckniqs]

What help is any of this to any of us if you are deliberately changing the values to stop people copying it? I thought the whole point in this thread was to share it?
....Are you just showing off?

[Zozo]

What help is any of this to any of us if you are deliberately changing the values to stop people copying it? I thought the whole point in this thread was to share it?
....Are you just showing off?

I'm not changing the values to stop people copying this. There was a component in question regards to it being correct or not. Yes this is an "Open Source" project for all.

Latest Gerber files below

Final2.rar

[Zozo]

Here's the latest "Sprint Layout 6 Project File

Final2.zip

[nrg-uk]

you have a 22ohm on the base of the 4427 should be 220 ohm

[teckniqs]

you have a 22ohm on the base of the 4427 should be 220 ohm

Another booby trap.

[Zozo]

you have a 22ohm on the base of the 4427 should be 220 ohm

Nice one NRG, It's easily done mistaking "RED RED BROWN" for "RED RED BLACK"

[Zozo]

you have a 22ohm on the base of the 4427 should be 220 ohm

Another booby trap.

No not really, just it would of have had reduced gain. Remember it's a timeline of working progress.

[Albert H]

You're really going to have problems with the eight fine tracks from the switches to the PIC - the way you had it before was much better. In my experience, really fine tracks can be a real problem, even when you get the boards made by commercial PCB companies.

Also - as others have pointed out, the oscillator layout has long tracks, which could make it prone to picking up hum. You really need to tighten up the layout in that area.

[reverend]

Quick question - how do people feel about putting a variable resistor to adjust the mod on a driver board? I hate them as they're the one thing guaranteed to go faulty over a period of time, and often go open circuit on the wiper meaning no mod at all. Same with variables to set the output power.

I know that there has to be some setting of level/power somewhere but in most installations you can just use a couple of fixed resistors which are then not prone to dust (and other crud) ingress.

Thoughts?

Rev

[Zozo]

Quick question - how do people feel about putting a variable resistor to adjust the mod on a driver board? I hate them as they're the one thing guaranteed to go faulty over a period of time, and often go open circuit on the wiper meaning no mod at all. Same with variables to set the output power.

I know that there has to be some setting of level/power somewhere but in most installations you can just use a couple of fixed resistors which are then not prone to dust (and other crud) ingress.

Thoughts?

Rev

That's a very good topic for debate, and you absolutely right about using just a simple resister network to achieve the same result. It'll be interesting to see what other people think.

My 2p worth on this would be, longevity over operating time. I'm guessing at this, but 2 years for one rig to be in operation without theft, or official removal is regarded as a long time. But I'll have to concede there's also other factors that can cause premature failure. I have seen some very rusty / oxidized rig boxes on here.