Anyone? Exiter TX's tested 1w to 7w models Sinus /rev / driver board / pira / nrg pll pro III / zozo

[rigmo]

Pira 5W run fine with BFS23A 13.8V 2.7W

[radium98]

rigmo pira tx is perfect , the only missed thing , is to hear a tone or the audio

[LeeCavanagh]

Birds are expensive... that statement has been a defining moment in my life.

Thanks for testing.

How come non of these have a relay to stop the polarity being put in the wrong way. Fuses that dont fix themselves when the issue have gone annoy me, but not as much as people who cant put a red wire to the + and a black wire to the -

[LeeCavanagh]

Never tested this, never made it, based on rdvv

[

[Albert H]

How come none of these have a relay to stop the polarity being put in the wrong way. Fuses that don't fix themselves when the issue has gone annoy me, but not as much as people who can't put a red wire to the + and a black wire to the - !

The simplest way to protect against reversed supply is a power diode in series with the positive lead. If the supply is reversed, nothing happens. The NRG boards didn't have this because at the time they were designed, the only diodes that would do the job would drop nearly a Volt, and if you were running from a battery (as many stations did) losing a Volt could significantly reduce the output power.

These days, I use either a Schottky diode (loses about 0.18V) in series, or a power FET (has to be P-channel for a positive supply) and a diode and a resistor to switch it on. The power FET won't conduct if reversed supply is applied, and only drops a few microvolts when conducting (its "on" resistance is a few milliohms!). Like this:

https://components101.com/articles/desi ... protection

[Albert H]

Never tested this, never made it, based on RDVV
[

They work, but they're not too clean - the PCB output filter isn't great.

[rigmo]

Pira 5W tuned 1w with 2n3553

[LeeCavanagh]

Who makes those boards for you ?

[rigmo]

Who makes those boards for you ?

Why you ask? what you need?

[LeeCavanagh]

I think they look great, the engraving or printing on the silver side too.

Do you guys test on your printed cb or do build on vero to start with whilst yo8 tweak?

Whats the cad programme used by the guys here, i seem to recall seeing the name on one image but cant find it, began with 'S' maybe Swift Cad?

I would at some point (and for now i’m still learning), to test making some, but do these companies charge a minimum batch?

I have some copper board here, some pens and crystals, its been eons since 9nmade a pcb but may try it again... clearly tho i prefer to buy where i can.

Does that help?

[jvok]

I don't think the metal cover is a pcb. Looks like a piece of sheet metal, probably etched on a laser.

I'll use veroboard or breadboard for prototyping low frequency/audio stuff like my stereo coder or an rds generator. Its no good for RF work or smd parts though. For that I'll sometimes just solder parts straight down to a blank sheet of PCB material and cut the tracks with a craft knife, or air wire straight between the pins. Even then with RF stuff youll often find it works different when you get it on a real PCB, so often its easier to just go straight to the pcb for prototyping. Especially with how cheap boards are nowadays, you can afford to throw a few away if it doesn't work first time.

The cad software your thinking of is probably Sprint Layout which I think is what rigmo uses. Theres tons of free and paid options though. EasyEDA is a popular one that runs in your browser, or if you prefer an offline one I use kicad which is open source and comes with a big parts library. Theres also Proteus which is paid but I think quite cheap. Whichever option you pick there'll be a learning curve, but once youve done a couple of layouts youll find you can almost do it with your eyes closed.

I use JLCPCB to get boards made, but OSH Park, PCBWay and others are good. Minimum order is usually 5 boards but they're insanely cheap and usually have special offers. I've paid a couple of quid for a batch of 5 before, a bit more if they're big boards. JLC will also do assembly for you for a bit more money which is nice, especially if your doing smd stuff.

[rigmo]

I've tried most drawing programs. in terms of simplicity and options BestBuy's offers is sprint layout 6

[LeeCavanagh]

Thanks jvok very informative, appreciated

Thanks rigmo, going to give it a go and try.

The only pcb I ever made was a 10w PA back in the late 80s, using a pen and some of those stick on circles tracks etc, worked but it wasn’t great to look at.

[rigmo]

the Jan Kolar "Pira" effort works reasonably well, though its performance is almost entirely determined by the construction of the inter-stage coupling transformer and the careful alignment of the output stage trimmer capacitor. It also has the (minor) inconvenience of using an obsolete PLL IC (which will be difficult to find in future) and the firmware forces a "re-tune" every half-hour, which can put small noise bursts on the carrier.

Albert Is this caused by not connecting pin 4 (MCLR, RA5, Vpp) to 5V through the 10k resistor?

[radium98]

could it be FrontDesigner30

[thewisepranker]

I don't think the metal cover is a pcb. Looks like a piece of sheet metal, probably etched on a laser.

It is a PCB, you can tell by looking at the edges - if it was a piece of sheet metal it'd have the same appearance throughout the entire thickness. Another giveaway is the order number etched in the bottom left corner. Given the format it looks like a JLCPCB order number. You can pay for them to omit it.

The artwork isn't etched, it's white silkskreen.

[radionortheast]

I had a transmitter that used the prescaler ic, it was clear across the fm band, had alot less ics than an old veronica/nrg pll. It had a spur that would sit high in the airband when it was put around 87. The oscillator was made up two transistors worked at half frequency, I remade it on breadboard got the samething, when I made at frequency oscillator with one transistor it went away. The older nrg/veronica’s think they used 4 transistors, I don’t know if its something they had.

[Albert H]

Birds are expensive... that statement has been a defining moment in my life.

Thanks for testing.

How come non of these have a relay to stop the polarity being put in the wrong way. Fuses that dont fix themselves when the issue have gone annoy me, but not as much as people who cant put a red wire to the + and a black wire to the -

Lee

Quicker than a relay, and much cheaper - I've always used Schottky Diodes in series with the positive supply lead. Reversal just means that the rig doesn't power up, and it's easy to add a "Power Error" LED to warn people that they're being stupid! Schottky diodes only "lose" about ~0.2V - not 0.65V that you "lose" with conventional silicon diodes. They are cheaply available up to 20A handling.

[Albert H]

I've just been trying out an exciter with an MRF555 output device. At 12.5V supply, it delivered exactly 2W on any frequency between 76 and 108 MHz. Closer examination showed that the designer had made a lot of effort to dissipate heat from the '555 into the board, and it was getting just 125mW of drive for its 2 Watts of clean output.

The oscillator was a twin "Kallitron" type (a bit like the NRG design), but done with FETs. The spectral purity was remarkable - there was no harmonic or spur product that was worse than -86dBc. The designer (a Dutch friend called Willem vd S) has spent a lot of time getting this just right, and has optimised the component values as far as is possible with standard range components.

The layout is neat, and designed for machine component insertion. His plan is to offer these as a ready-made board for around €70 each (much cheaper in quantity). Frequency selection is by BCD-coded rotary switches, DIP switches, or even solder blobs (for the cheapskates!). There is a simple deviation clipper fitted as part of the modulation circuit, and the modulation sensitivity is exactly 1.55V p-p into 600Ω for 75kHz, though this can be changed by replacing one resistor if necessary.

As soon as I get the go-ahead from the designer, I'll put some photos up on here with details of how to get them if you want them.....!

[radionortheast]

suppose it would be nice to be able to get build up transmitter boards again, I used to be able to go to nrg kits, I do miss the old days, later on when pcs came along it was quite easy to get them from them, they would come straight through, there are fees now, your not given a way to pay at the checkout, it can be quite upsetting, your trying to settle the vat and fees fedex/tnt put on top of it. I tend to just find bare boards on ebay, hard to get working without a full kit of parts, I tried afew years ago couldn't get it working.