SINUS B1 PROJECT

[radium98]

did you ever make a little video ?

[radium98]

Sinus for technical information question,can you detail the IF 10,7 mixer transformer ONLY,i would like to experiment in re bwinding from scrapp an 455 khz AM coil to transform it to 10.7 MF transformer .
thanks.

[sinus trouble]

[radium98]

wonderfulllllllllllllllll work. keep thing up.

[radium98]

Sinus for technical information question,can you detail the IF 10,7 mixer transformer ONLY,i would like to experiment in re bwinding from scrapp an 455 khz AM coil to transform it to 10.7 MF transformer .
thanks.

Sinus for technical information question,can you detail the IF 10,7 mixer transformer ONLY,i would like to experiment in re bwinding from scrapp an 455 khz AM coil to transform it to 10.7 MF transformer .
thanks.

[sinus trouble]

As you can see, You can wind your own coils

IF transformer = 10 turns primary. 3 turns secondary on 5mm diameter former approx. (C8 will need to be used for resonance)

I must warn you in advance! These are approximate dimentions! Fitting the shield case will severely derate the inductance!

I suggest that you do a test wind, measure the inductance and compensate with more turns.

Here Also is the link for Enigma Shop where I purchased the IF Coil

https://www.enigma-shop.com/index.php?o ... hz-i-f-can

[sinus trouble]

Apologies for the delay.

As mentioned, you could use the above? But only without the shield case fitted!

[radium98]

thank you my freind sinus

[XXL]

I couldn’t get mine working . Iv checked everything. No oscillation. I’m using cheap China Varicaps though. Maybe that’s why. I haven’t tried it with real ones yet.

[Bton-FM]

I couldn’t get mine working . Iv checked everything. No oscillation. I’m using cheap China Varicaps though. Maybe that’s why. I haven’t tried it with real ones yet.

You could try replacing the varicap with a trimmer.

[sinus trouble]

I couldn’t get mine working . Iv checked everything. No oscillation. I’m using cheap China Varicaps though. Maybe that’s why. I haven’t tried it with real ones yet.

Sorry to hear that your having trouble with your build

Beware of counterfeit BF199s too! They do have a unusual Pin configuration so it may be worth checking that your ones correspond with the datasheet.

Assuming that you've checked DC voltage is getting to the Oscillator, Varicaps and Output stage? Im surprised it wont oscillate at all?

With the 'Tune' trimmer in centre, You should have around 28Mhz ish on each BF199 Also check that your 2N4427 is not shorting on any of the through hole pads? I use a spacer just to be safe.

Finally, You could try removing some capacitors that i have marked in red rectangles below.
I added them to the circuit just to sharpen tuning but are not really necessary.

20200722_181202 - Copy.jpg

[radium98]

sinus can you post the vco with it prints ,i did not find this thanks.

[XXL]

Only thing i have changed is:

R5 Was 5.6 substituted for 4.7ohm
78l08 substituted for 78l09.
Using blue trimmer pots instead of cables to a chassis mount pot. (i know they're unstable, it just for testing)
and on C6 im using a 100pf and 47pf in the same slot because I didn't have a 147pf cap which still equals to 147pf.

Other than that im getting voltage on the MV104 varicaps and goes up and down in voltage when i move the 10k pot.

[radium98]

sinus trouble PM sent on the outlook

[sinus trouble]

My sincere apologies XXL, I seem to have made a slight cockup here.

I have just checked the PCB prototype and i used the KV1330 varicap which is higher in capacitance than the MV104.

The MV104 is perfectly OK to use but you will need to add more capacitance to C6, Maybe swap the 47pf for a 68 or 100pf?

Or add a temporary trimmer across C6 to dial in the frequency.

Also defo remove those 4 capacitors that i mentioned above, They could be causing problems!

Anyways give it a try and let me know how you get on?

[sinus trouble]

sinus trouble PM sent on the outlook

No worries Radium, I will post soon.

[XXL]

Yeh i put the 2 caps on the back of the board and added a 33pf trimmer on top. still nothing. the final transistor gets hot though if its at full voltage. its drawing 21ma so its doing something, but iv never used this oscillator design before so I'm not sure what's going on.

[sinus trouble]

Yeh i put the 2 caps on the back of the board and added a 33pf trimmer on top. still nothing. the final transistor gets hot though if its at full voltage. its drawing 21ma so its doing something, but iv never used this oscillator design before so I'm not sure what's going on.

Hmm? Strange?

The 2N4427 will get warm because its operating in Class A. The circuit should consume around 80/90mA when operating.

What test equipment do you have access to?

Also did you remove the 4 caps that i mentioned?

[XXL]

Yeh 4 caps removed. Iv only got a swr meter and a frequency counter. Iv also checked it over with the multimeter.

[sinus trouble]

Oh Ok!

Its hard to diagnose whats happening without seeing the PCB?

You could try tuning a radio to around 87Mhz and placing the antenna close, see if you get any reaction when adjusting the tuning pot?

The circuit should be oscillating somewhere if its been built correctly? Its just a matter of finding where that is?