Low level AM Transmitter Circuit and little description.

Status
Not open for further replies.
hi,
i think i saw such simple circuits in older ham magasins and recently on the internet,
By the way , i found a circuit on my laptop (downloaded in the past... ) , i wonder what is it for ? (and why did i save it )

can it be a little grid-dip meter ?
 

i think i saw such simple circuits in older ham magasins and recently on the internet,
Click to expand...
Yes it is an old way . many of the peoples that haven't access to the PWR meter or ... using these circuits !
By the way , i found a circuit on my laptop (downloaded in the past... ) , i wonder what is it for ? (and why did i save it )

can it be a little grid-dip meter ?
Click to expand...

Ha ha ! you are alike me ! i have gang of circuits in my computer but i don't know why i have saved many of them !!! too :grin:
Yes it seems a grid dip meter ! because it is like an oscillator and then a micro ammeter to indicate it's ratio . ( you knew it's name !!! :smile: )
 

The emitter-coupled oscillator is belonging to the class of negative impedance oscillators. The negative impedance can be adjusted by the emitter resistor respectively a current source over a wide range.
 
Hi Zsolt1
What are the wave forms that i can see in your post #143 ? gate of what ? drain of what ?
Best Wishes
Goldsmith
 

hi,
you asked for measurements in post #108 from the oscilator. It's built with jfet (BF244) not bjt.
:grin:
 

you asked for measurements in post #108 from the oscilator. It's built with jfet (BF244) not bjt.
Click to expand...
Are you referring to the circuit originally shown in post #28? There should be a MHz carrier signal rather than 2.5 kHz?
 

yes it's the same circuit as i sed in post 83 i belive, anyway it's the transmitter i built and i posted a picture about it to .... My transmiter has multiple coil pairs, so i can cover a large range, i did the measurements on a random position of the switch, so a diferent wawe length was selected. Actually it was on 7 MHz before i conected the scope (it has a frequency meter with a lcd on the front panel) , the frequency changed when i conected the scope . I suspect that it oscillates because magnetic linkage of coils. (frequency changes a little when i re-asamble the metalic box, now i remember that's why i had some trouble with coil dimensioning... :grin: )
Any way Eshal's new circuit will work better with the new oscillator, so i belive we progressed a little... :grin:
 

hi,
you asked for measurements in post #108 from the oscilator. It's built with jfet (BF244) not bjt.
Click to expand...
Hi My friend
Oh yes , now i can remember ! that's brilliant , however with a little change in quiescent point you can increase it's amplitude more .
remember that's why i had some trouble with coil dimensioning.
Click to expand...
Why trouble ? did you try sandwich winding ? ( at first it seems delicious ! and at second it will consequence lesser leakage ! :grin: )
And a law : when you want make a high precision transmitter , there are some ways to create a fixed frequency carrier signal , first is a crystal oscillator ( like miller's oscillator ) . or a low frequency oscillator and then a or some frequency multipliers ! ( there are many other ways , available too )
Best Regards
Goldsmith
 


Hello I hope I can help you.
I read somewhere that you can make a AM transmitter just by using a stabilizer like the LM317.

Maybe you can find that article. Building it should be a peace of cake !

<good luck !> Regards.

I read somewhere that building a AM transmitter can easily be done with a Stabilizer like the LM317.
I do not know exactly where I found it a few years back, I'm sorry but hope you do find it ! Albert.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…