Greetings Necks! Its been A while!
I have been working on short range but decent quality link based on B1 so i thought i would share.
Below is the receiver and the transmitter.
The receiver is set to the lower end of the band (48 to 60) and tuned to a specific frequency,
The transmitter is tuned via a potentiometer.

Sinus - nice looking boards. You can improve the reliability of the link by adding AFC to the receiver. This will help to compensate for the drift in the receiver VFO and for any drift in the link transmitter!

All you need is to add a varicap diode and a capacitor to the VFO, and take the RSSI output from the CA3089 through a high value resistor to bias the varicap - you'll find that it'll lock on really well. I used to use this trick a lot back in the 80s (usually up on Band III, before the DAB put paid to the use of ~200MHz). My receivers would track over about 400 kHz, so they'd compensate for a lot of thermal drift!

Thanks Albert!

Although i do like the oldskool manual etching? JLCPCB can do it far better and cheaper than i could ever do!

The receiver started out as a project on ugly copper clad, I experimented with many local oscillator and mixer stages and did originally pick up the usual 88-108 band. Your B1 schematic that you posted a while back was a great basis for me to go by!

I also have to thank Teckniqs, WP and NRG-UK for all the support, Also Engima and Cricklewood for help sourcing the parts!

I know that the CA3089 does have an AFC which helps to stabilise the detector circuit which is fully functional in my PCB, However your advice on local oscillator tracking is very interesting! I will defo be looking into that!

good project ,good luck ,but why not adding the pll tuning to it the one of pira ?
a filed strenght meter from pin 13 ? also

Looks great, Sinus, and nice to some of all the old necks still around.

What frequency range & output power is the TX mate?

This looks great!

Have you etched the coils on the output device? I don’t see any hand wound ones around it.

You are right, JLCPCB is so much easier, cheaper and less messy.The board quality is good as well for the price.

from the original maker .for the onw qho qant to take infos .another time good work and nice plate freind SINUS

radium98 wrote: ↑Fri Jul 31, 2020 7:33 am good project ,good luck ,but why not adding the pll tuning to it the one of pira ?
a filed strenght meter from pin 13 ? also

Thanks Radium

I did consider a PLL? But i do not think the SAA1057 or the TSA5511 are suitable? The MC14570 would probably do a better job?

I also can be a bit old fashioned with my projects, The 'Link box' i was familiar with in the past always had Fine tune dial built in! Its far from perfect but is surprisingly stable, I guess as the oscillator is running at only around 27Mhz it defo helps!

MiXiN wrote: ↑Fri Jul 31, 2020 9:44 am Looks great, Sinus, and nice to some of all the old necks still around.

What frequency range & output power is the TX mate?

Thanks Mixin

The frequency range is 53 - 60Mhz

The power output is only small, around 300mW max? But the gain is restricted and remarkably flat across the tuning scale

Bton-FM wrote: ↑Fri Jul 31, 2020 11:07 am This looks great!

Have you etched the coils on the output device? I don’t see any hand wound ones around it.

You are right, JLCPCB is so much easier, cheaper and less messy.The board quality is good as well for the price.

Thanks Bton

Nope, There are no hidden striplines underneath I guess there is a small inductance in the traces themselves ofcourse but nothing substantial.

Sinus did you see my PM ?

radium98 wrote: ↑Sat Aug 01, 2020 6:43 am Sinus did you see my PM ?

I have not, i will check now

Just to make things clear before anyone asks, These items are not for sale

Here is the schematic for the Receiver for those who requested.

Hmm do you not getting oscilation when you tune to max signal ?
Why not using the original design with a BF199 as a preamp ?

sinus HUG .

RF-Head wrote: ↑Wed Aug 05, 2020 8:26 am Hmm do you not getting oscilation when you tune to max signal ?

Ive not noticed any strange behavior as yet? But its still early days.

I will try to post some rough measurements soon!

RF-Head wrote: ↑Wed Aug 05, 2020 8:26 am
Why not using the original design with a BF199 as a preamp ?

Im not familiar with the design you are referring too? This is the only one i have.

I have seen other 'pirate' designs in the past but never got a chance to study them in any detail.

sinus trouble wrote: ↑Wed Aug 05, 2020 1:29 am Here is the schematic for the Receiver for those who requested.

That's quite close to the circuit I developed in the early 80s, except that the oscillator had a crystal and a frequency multiplier to get it up to where it was wanted, and there was a grounded base RF amplifier on the way in.

Other versions used AFC instead of crystal control, or simple PLL circuits for the local oscillator. Back in those days, they were mostly built for around 200MHz (DAB hadn't started yet).

There was another version, with Lecher Lines for the filters and the Local Oscillator, which could be set up for 450 - 700 MHz. This was what I used for my stations, because we could use ordinary, cheap TV Yagis at each end: Nobody pays attention to an ordinary telly aerial!