School Project

[N0WVA]

I'm still considering both a TX and RX built you do raise good points... I'm looking at a few kits and they seem to be about $10 which is not bad. I'm debating between buying kits or building kits, I'd like to make this as cheap as possible with components I can find here at RIT for free from a variety of sources... It's a simple design and one that the club could produce it's own boards, Im sure this is usually more expensive but I wonder if in this case it wouldn't.
Building the receiver for more interested students seems like a more viable option the more I am looking at this.
I am looking at this website at the moment.

http://members.tripod.com/~transmitters/begin.htm

The two transistor stage transmitter is the way to go. The single transistor ones arent very sensitive audio wise.

[KI4TJ]

I want to promote deadbug because I feel that it helps promote spontaneous experimenting, you don't need a kit and it is impractical to build an HF circuit on a breadboard.

Any thoughts on why breadboards are impractical? All my initial experimenting is on a breadboard unless it involves HV and tubes. Then it's point to point. I find the breadboard is quicker than anything that requires soldering. I'm a newb myself, though, so I'm interested to know what the downside is.

[KB1LQD]

Any thoughts on why breadboards are impractical? All my initial experimenting is on a breadboard unless it involves HV and tubes. Then it's point to point. I find the breadboard is quicker than anything that requires soldering. I'm a newb myself, though, so I'm interested to know what the downside is.

Well I do breadboard and it is very useful and popular. The downside is that unlike deadbug, the circuits are not "permanent", components and fall out, leads pushed and shorted into other leads, and so on. Also with HF circuits there can be a lot of undesirable effects from the capacitance and spaced out leads at higher frequencies. Although the capacitance and other effects are usually negligible, at higher frequencies they can prove problematic

I just got home last night for RIT spring break, I'll be working on this now that I have some time to think as we just finished winter quarter finals! Ouch....

[KB2BLS]

There is always the old Neophyte Receiver. Parts are still available and it is complicated enough to be interesting but easy to build. It can be ugly wired or printed circuit boards can be made.

Feb. 1988 issue of QST pp 14-18
or
www.arrl.org/tis/info/pdf/28814.pdf

[KB1LQD]

There is always the old Neophyte Receiver. Parts are still available and it is complicated enough to be interesting but easy to build. It can be ugly wired or printed circuit boards can be made.

Feb. 1988 issue of QST pp 14-18
or
www.arrl.org/tis/info/pdf/28814.pdf

Thank You, I haven't seen this before but look very interesting, something I am going to keep for future projects.


Well,
I constructed a Very Very Very quick version of the Aaron Cake (http://www.aaroncake.net/circuits/fmtrans.asp) fm bug, I had almost no component values and resorted to series and parallel combination (long leads...). I had no idea what variable capacitor I had (ARCO site is down...) so I guess and hoped it'd work. I ended up at about 140 mHz with alot of drift. No worries I used a 50 ohm termination and a frequency counter.... Not a giant antenna off the ham bands! The little thing worked even though the varying components and shifty construction (long leads, very little time...) I think the FM bug is the way we are going and Im hoping to talk with my club-mates further about it!

EDIT: I brought the frequency down through parallel capacitors and trial and error...

[KB1LQD]

Just rebuilt the FM transmitter and go it pretty stable! Im making the coils on a wooden dowel with liquid nail polish to hold them, that should take out the last of the frequency drifting without changing the circuit. I am planning on modifying the circuit to accept an audio input instead on the electret mic, seems to be the consensus of what people want. I will get some pictures up soon!

[KB1LQD]

I just finished the transmitter, just got to lay out the PCB board and use the toner method to make the boards. I decided to go with a slightly different circuit, one that employs a better colpitts Oscillator and a buffer amplifier. I have attached two pictures, the circuit came out pretty nice using the deadbug method.

After laying out the board I am going to try the toner transfer method of etching, although I have etched boards in the past, I have not used this method before, does anyone have any tips for using this method at VHF frequencies?

[KB1LQD]

Here is a link to the in progress webpage!

http://www.rit.edu/sg/amateurradiocl...ransmitter_kit

As I get free time (haha... Funny....) I will get the nearly completed board copper file on the site, and more picutres as the event happens. Thanks for everyones suggestions!