One Last FM Exciter.

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Zozo
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Re: One Last FM Exciter.

Post by Zozo » Wed Mar 10, 2021 12:43 pm

Albert H wrote: Wed Mar 10, 2021 1:33 am 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.
Thanks Albert, I did order the sample PCB mostly to check the tolerances on the through-hole components and foot prints to some components in close proximity to each other.

If the tracks do not turn out ok, I'll have to revert back to an earlier revision.

The tracks to the OSC have been the main case of criticism, I'll try and see what I can do.
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Re: One Last FM Exciter.

Post by sinus trouble » Sat Mar 13, 2021 12:34 am

reverend wrote: Wed Mar 10, 2021 8:56 am 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
Personally i have never had any problems with 'Trimmers' as in most installations they are rarely adjusted? Using the wrong tool often leads to premature failure of such components.

On the other hand? The cost is also an issue? So it makes sense to use fixed components unless absolutely necessary.

Realistically there is no simple solution to adjusting settings if that is what you are looking for? Digital options are available? But still expensive and involve mechanical wearable parts.
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Re: One Last FM Exciter.

Post by Zozo » Tue Mar 16, 2021 11:01 pm

Update: Sample PCB's should be here tomorrow. DHL tracking currently shows the following "Estimated Delivery Date
March, 17 2021 - By End of Day"

Fingers crossed.
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Re: One Last FM Exciter.

Post by Zozo » Wed Mar 17, 2021 5:15 pm

So the sample PCB's arrived today. I've made a start at populating it with components, but I'm not as quick as I use to be.

So far all seems to be fine with spacing and component foot prints. I did notice the center hold for the 4:1 transformer might be a bit on the small size, but that's the only thing so far.

Just to recap, this is revision 1A which is only for testing. I'm currently up to Rev 1c, which has improvements with track reduction in the OSC stage and general tiding up of the board. I'll release the Gerber and project files for this soon.

I'll hopefully have something more interesting to show everyone sometime over the weekend.

Finally the small tracks used for the DIP switches from the PIC16F84 didn't seem to be a problem at all, I have now checked JLCPCB Capabilities section on there website, and can see they offer even smaller tracks for BGA and VLSI integrated circuits. So what I ordered was a walk in the park for them.
20210317_165503.jpg
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Re: One Last FM Exciter.

Post by Bton-FM » Wed Mar 17, 2021 5:38 pm

Zozo wrote: Wed Mar 17, 2021 5:15 pm So the sample PCB's arrived today. I've made a start at populating it with components, but I'm not as quick as I use to be.

So far all seems to be fine with spacing and component foot prints. I did notice the center hold for the 4:1 transformer might be a bit on the small size, but that's the only thing so far.

Just to recap, this is revision 1A which is only for testing. I'm currently up to Rev 1c, which has improvements with track reduction in the OSC stage and general tiding up of the board. I'll release the Gerber and project files for this soon.

I'll hopefully have something more interesting to show everyone sometime over the weekend.

Finally the small tracks used for the DIP switches from the PIC16F84 didn't seem to be a problem at all, I have now checked JLCPCB Capabilities section on there website, and can see they offer even smaller tracks for BGA and VLSI integrated circuits. So what I ordered was a walk in the park for them.

20210317_165503.jpg
Which PCB house did you use? It doesn’t look like the JLC boards.

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Re: One Last FM Exciter.

Post by Zozo » Wed Mar 17, 2021 5:53 pm

Bton-FM wrote: Wed Mar 17, 2021 5:38 pm
Zozo wrote: Wed Mar 17, 2021 5:15 pm So the sample PCB's arrived today. I've made a start at populating it with components, but I'm not as quick as I use to be.

So far all seems to be fine with spacing and component foot prints. I did notice the center hold for the 4:1 transformer might be a bit on the small size, but that's the only thing so far.

Just to recap, this is revision 1A which is only for testing. I'm currently up to Rev 1c, which has improvements with track reduction in the OSC stage and general tiding up of the board. I'll release the Gerber and project files for this soon.

I'll hopefully have something more interesting to show everyone sometime over the weekend.

Finally the small tracks used for the DIP switches from the PIC16F84 didn't seem to be a problem at all, I have now checked JLCPCB Capabilities section on there website, and can see they offer even smaller tracks for BGA and VLSI integrated circuits. So what I ordered was a walk in the park for them.

20210317_165503.jpg
Which PCB house did you use? It doesn’t look like the JLC boards.
I used JLC. Can't really complain with the quality or delivery, They seem really good.
20210317_174947.jpg
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Re: One Last FM Exciter.

Post by radium98 » Wed Mar 17, 2021 7:24 pm

wonderful Zozo

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Re: One Last FM Exciter.

Post by Bton-FM » Wed Mar 17, 2021 8:24 pm

Zozo wrote: Wed Mar 17, 2021 5:53 pm
Bton-FM wrote: Wed Mar 17, 2021 5:38 pm
Zozo wrote: Wed Mar 17, 2021 5:15 pm So the sample PCB's arrived today. I've made a start at populating it with components, but I'm not as quick as I use to be.

So far all seems to be fine with spacing and component foot prints. I did notice the center hold for the 4:1 transformer might be a bit on the small size, but that's the only thing so far.

Just to recap, this is revision 1A which is only for testing. I'm currently up to Rev 1c, which has improvements with track reduction in the OSC stage and general tiding up of the board. I'll release the Gerber and project files for this soon.

I'll hopefully have something more interesting to show everyone sometime over the weekend.

Finally the small tracks used for the DIP switches from the PIC16F84 didn't seem to be a problem at all, I have now checked JLCPCB Capabilities section on there website, and can see they offer even smaller tracks for BGA and VLSI integrated circuits. So what I ordered was a walk in the park for them.

20210317_165503.jpg
Which PCB house did you use? It doesn’t look like the JLC boards.
I used JLC. Can't really complain with the quality or delivery, They seem really good.

20210317_174947.jpg
The silk layer looked matte to me rather than shiny but I think that's just the photo. That's why I thought it was made by a different manufacture.

JLC are brilliant - I've used them a couple of times now, they never disappoint. Great quality PCBs as well especially considering the price!

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Re: One Last FM Exciter.

Post by Zozo » Thu Mar 18, 2021 10:34 am

radium98 wrote: Wed Mar 17, 2021 7:24 pm wonderful Zozo
Thanks Radium, It'll look even better once all the components have been placed.
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Re: One Last FM Exciter.

Post by Zozo » Thu Mar 18, 2021 10:39 am

Bton-FM wrote: Wed Mar 17, 2021 8:24 pm
The silk layer looked matte to me rather than shiny but I think that's just the photo. That's why I thought it was made by a different manufacture.

JLC are brilliant - I've used them a couple of times now, they never disappoint. Great quality PCBs as well especially considering the price!
Yes perhaps the photo is not doing the board much justice, compared to how it looks to the naked eye. Have to agree with you on JLC, what you get for what you pay is incredibly great value for money.
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Re: One Last FM Exciter.

Post by sinus trouble » Thu Mar 18, 2021 10:59 pm

Nice work ZoZo! :)

Just a coincidence, But my PCBs arrived yesterday too! I managed to complete a test board today and its looking much better than i expected!

I will post a quick preview here, The schematic and other details will follow soon in the relevant thread as they need some updates confirmed.
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Re: One Last FM Exciter.

Post by sinus trouble » Thu Mar 18, 2021 11:03 pm

Sinus PLL V2.jpg
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Re: One Last FM Exciter.

Post by Zozo » Thu Mar 18, 2021 11:46 pm

sinus trouble wrote: Thu Mar 18, 2021 10:59 pm Nice work ZoZo! :)

Just a coincidence, But my PCBs arrived yesterday too! I managed to complete a test board today and its looking much better than i expected!

I will post a quick preview here, The schematic and other details will follow soon in the relevant thread as they need some updates confirmed.
Cheers Sinus, Your PCB looks very nice. I'm trying to imagine what it would look like if you had gone for the black solder masking ;) . I don't know why I'm so obsessed with that particular color of PCB, might be a "BW" thing.

I didn't manage to get any more done today, I had other things I needed to do. Plus got to keep the XYL happy, otherwise I'll be in her bad books. I'll look forward to any more updates on your design as and when they are ready to publish.

I did have another idea for this design I'm thinking of, which I may or may not do. But the idea was adding an "OLPD" function using your PLL "Test Pin" circuit you designed. Anyhow it's just a idea, and to be honest I'll probably stop with the final "Revision 1c".
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Re: One Last FM Exciter.

Post by sinus trouble » Fri Mar 19, 2021 12:19 am

I know what you mean, Other commitments are more important!

Anyways I did experiment with OLPD a while back, The sudden jump of current as the PA stage kicked in would de-stabilise the lock state?

This version does seem to be much more stable than previously observed? So there is hope ahead?
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Re: One Last FM Exciter.

Post by reverend » Fri Mar 19, 2021 9:13 am

sinus trouble wrote: Fri Mar 19, 2021 12:19 amThe sudden jump of current as the PA stage kicked in would de-stabilise the lock state
This can happen really easily, depending on how well buffered your VCO is. I find the easiest solution is to bring up the power slowly by simply putting a reasonable sized capacitor across whatever it is you are using to do the OLPD (a transistor typically, so across the base). If you slow if down enough, the PLL won't lose lock.

It amazes me that folk spend so much time on 'fast lock' circuits. Yes, without one a PLL may take several seconds to lock up but it's not like you change frequency or switch the TX on and off every few minutes.

Rev

P.S. Zozo - I like the fact that your board has my moniker on it :D
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Re: One Last FM Exciter.

Post by Albert H » Fri Mar 19, 2021 11:12 am

Rev - agreed about "fast lock" - my PLL takes between 10 and 15 seconds (according to frequency) to lock, and the modulation is tilt-free down to about 15 Hz! There is no point in having the PLL lock quickly - we're not switching the carrier on and off rapidly like we might in communications transmission.

I also use a fairly slow PLL lock time for my AM gear too. This ensures that the PLL doesn't do anything strange when there's big currents being pulled by the modulator.

We're broadcasting, not sending short messages!
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Re: One Last FM Exciter.

Post by Zozo » Fri Mar 19, 2021 3:06 pm

reverend wrote: Fri Mar 19, 2021 9:13 am
sinus trouble wrote: Fri Mar 19, 2021 12:19 amThe sudden jump of current as the PA stage kicked in would de-stabilise the lock state
This can happen really easily, depending on how well buffered your VCO is. I find the easiest solution is to bring up the power slowly by simply putting a reasonable sized capacitor across whatever it is you are using to do the OLPD (a transistor typically, so across the base). If you slow if down enough, the PLL won't lose lock.

It amazes me that folk spend so much time on 'fast lock' circuits. Yes, without one a PLL may take several seconds to lock up but it's not like you change frequency or switch the TX on and off every few minutes.

Rev

P.S. Zozo - I like the fact that your board has my moniker on it :D
Yes I agree with you Rev. I don't think a few seconds to achieve lock really matters that much. As you say "it's not like you change frequency or switch the TX on and off every few minutes"

Yes I just noticed what you mean about the moniker in the bottom left corner. Perhaps I should offer out an "Advertise Here" on the finished revision :D
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Re: One Last FM Exciter.

Post by sinus trouble » Fri Mar 19, 2021 10:54 pm

reverend wrote: Fri Mar 19, 2021 9:13 am This can happen really easily, depending on how well buffered your VCO is. I find the easiest solution is to bring up the power slowly by simply putting a reasonable sized capacitor across whatever it is you are using to do the OLPD (a transistor typically, so across the base). If you slow if down enough, the PLL won't lose lock.
Interesting Rev, A kinda 'Soft start' deffo makes alot of sense!

Its hard to explain how the Lock indicator works on my exciter? Where as say the TSA5511 communicates with the PIC to initiate a Lock state? This one operates in what i would call a 'Real time' fashion?

The LED is normally off and only lights when out of Lock or an external influence gets too close to the oscillator?

Over modulation also causes flicker.

Anyways, I will give your advice a try! :)
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Re: RE: Re: One Last FM Exciter.

Post by Electronically » Sat Mar 20, 2021 12:26 am

sinus trouble wrote:
reverend wrote: Fri Mar 19, 2021 9:13 am This can happen really easily, depending on how well buffered your VCO is. I find the easiest solution is to bring up the power slowly by simply putting a reasonable sized capacitor across whatever it is you are using to do the OLPD (a transistor typically, so across the base). If you slow if down enough, the PLL won't lose lock.
Interesting Rev, A kinda 'Soft start' deffo makes alot of sense!

Its hard to explain how the Lock indicator works on my exciter? Where as say the TSA5511 communicates with the PIC to initiate a Lock state? This one operates in what i would call a 'Real time' fashion?

The LED is normally off and only lights when out of Lock or an external influence gets too close to the oscillator?

Over modulation also causes flicker.

Anyways, I will give your advice a try! :)
Correct it's important to give it a slow start for locking you'll benefit from it in the long run. The rule of the thumb is make things run to fast they tend to burn out faster so slower the better.

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Re: One Last FM Exciter.

Post by sinus trouble » Sat Mar 20, 2021 1:04 am

Electronically, I agree on most aspects :)

Ofcourse i want to stick to so called 'Regulations' But sometimes protection can become problematic? The same applies to SWR protection, It could go into an endless cycle of powering up and down!

To have a balanced practical application is sometimes easier said than done?
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