Thank you sinus
i think XXL is using fake transistor ,a look to what he said is a good idea .
2n2219a for this work ? as his FT go to 250 mhz

Sinus someone at the door PM.

radium98 wrote: ↑Wed Oct 21, 2020 6:32 am Thank you sinus
i think XXL is using fake transistor ,a look to what he said is a good idea .
2n2219a for this work ? as his FT go to 250 mhz

No Worries! Thanks for the PM

I have not used the 2N2219? But i dont see why it will not work? Maybe some tweaking might be needed?

Band 1 being quite low in terms of frequency range may even permit the use of BC547s?

The oscillator is easily built on a copper clad board if you wish to experiment!

No i did not build it yet it will take some time.Yes simple as is and brilliant no exotic components,and if well done must work from the first power on ,what value for the POT trimmer 10 k or ? yes it is not critical ,but what is best .

Heres a very short video that i found of the B1 RX operating out of band.

As i had just assembled it, I thought id see if i could pick up something from the lower end of the Band 2 spectrum.

i congratulate you my freind for the good work , also we got the same idea to catch a commercial fm broadcast , but i did not make it yet , also you cane make it as a field meter if adding variable attenuator and good tuning

What will happen once the 10.7mhz tokos dry up ? Is there a modern day equivalent or alternative?

you can roll youre own and made a little square copper can , or find a 6 AM radio pocket transistor and remove them , it is a very hard work indeed . but may do the job

Would you be able to post up how to make them? I’d prefer to just make them now tbh rather than buying them. Would they work the same or not as accurate ?

OldskoolPirate wrote: ↑Sun Mar 27, 2022 5:14 pm What will happen once the 10.7mhz tokos dry up ? Is there a modern day equivalent or alternative?

Unfortunately i have not seen any direct replacement as yet?

Mr Radium is correct! If you look back to previous posts on this thread, I did give the rough dimensions for 'Hand wound' TOKOs

I used 'Skeleton coil formers' A simple LC meter also helps with getting the inductance spot on (Or close at least)

I used them on my first prototype which worked really well!

how comes on the output your design has 2 trimmers and 2 air coils ? wouldn't it be easier and less parts to just use 2 green toko like this photo ?

no because it act as a selective filter and tuned circuit , for a better sensitivity and reception .

Surely the slug in the toko is doing the same thing as the trimmers ? With a cap to ground of course.

Good question Oldskool!

Firstly just to clarify that is the Input filter that comes from the antenna! Not the output! (The Output is the on the opposites side)

The filter can be configured either way and the PCB is designed to fit tunable coils if you wish?

However the reason i chose that configuration was the input needs to be tapped onto the first coil to match the impedance! (1 1/2 turns from ground) This would be difficult to do on a moulded coil!

I guess that makes sense? But i will find a picture to show how the input is connected!

Here is a look at how the antenna Input is coupled to the receiver!
The Input is soldered to the topside of the second turn (1 1/2 turns from ground)

I’m still trying to figure out why my TX isn’t working. Iv swapped out the mv104s for 4 bb809 facing each other. I get a fixed 4.5v on the input of the top diodes and 1-12v depending on what the resistor pot is set to on the lower diodes.

Iv got around 8v on all pins on the bf199s. That don’t sound right.

No RF detected anywhere but drawing 20ma at 12v

maybe fake bf199 , try bf494 , i did not try any but just giving an idea .

OldskoolPirate wrote: ↑Mon Mar 28, 2022 9:49 pm Surely the slug in the toko is doing the same thing as the trimmers ? With a cap to ground of course.

The "Q" of the air-cored coils will be much higher, giving much tighter tuning.

XXL wrote: ↑Wed Mar 30, 2022 1:04 am I’m still trying to figure out why my TX isn’t working. Iv swapped out the mv104s for 4 bb809 facing each other. I get a fixed 4.5v on the input of the top diodes and 1-12v depending on what the resistor pot is set to on the lower diodes.

Iv got around 8v on all pins on the bf199s. That don’t sound right.

No RF detected anywhere but drawing 20ma at 12v

I am sorry to hear you are still experiencing problems!

The audio varicap is fed from the 8V regulator via a potential divider which halves the voltage to 4V! After passing through the 6K8 resistor, The varicap sees a bit less than 4V.

I doubt that is the source of the issue though? The tuning circuit also seems to be working as it should?

The Collectors of the BF199s should see 8V DC! The Base and Emitter should NOT!

Assuming that your capacitors and resistors are correct? This would indicate that one or both of the BF199s are not functioning as they should?