***
>
> I originally posted this a month ago but I don't think it got onto the
> newsgroup. I will post it again because I am preparing to make a new post.
>
> ***
>
> Thankyou to everyone who has responded to my post. I appreciate that a
> little bit of feedback makes a task seem less daunting 8). I am going to
> go and buy the parts and try to construct a replacement transmitter. I
> will let you know how well it goes.
>
> (Current ASCII Schematic) View in Courier font:
>
> V+ ---+ 6VDC **
> | | E *
> o | B *
> / | C *
> o **
> |
> +-----+--[L1]--+------+-----+-------+
> | | | | | |
> | [10K] [Xtal] | [30pF] [100pF]
> | | | /c | |
> [10nF] +--------+----| | +-----[L2]---Antenna
> | | \e | |
> | | | | |
> | | +-----+ |
> | | | |
> | [5K1] [100R] [50pF]
> | | | |
> Gnd---+-----+---------------------+-------+
>
> L1 is possibly an inductor (RF Choke) or a combination inductor capacitor.
> L2 is a set of windings to decrease the size of the antenna. Xtal is set
> at 27.145MHz
>
> +------+------+----+-----+-------+-+--------+
> | |PD@25C|VCEO|IC |Hfe |@|IC(cont)|
> +------+------+----+-----+-------+-+--------+
> |ED1702|625mW |25V |500mA|132-189|@|100mA | Original
> +------+------+----+-----+-------+-+--------+
> |BC338 |625mW |30V |800mA|100-630|@|100mA | Proposed Replacement
> +------+------+----+-----+-------+-+--------+
>
> JK> Do you have a picture of the PCB itself somewhere?
>
> Very difficult to get a picture that isn't blurry with my current
> equipment.
>
> JK> I'd trust the scope over the meter.
>
> I think I have been using it wrong 8). I'll make the readings again and
> resubmit.
>
> JK> Wes Hayward (1994-2000) "Introduction to Radio Frequency Design" 3rd
> Printing, American Radio Relay League
> JK>
formatting link
> JAL> "Three-transistor Toy CB Walkie-Talkie"
> JAL> single-transistor superregenerative detector
> JAL> Thomas H. Lee (2004) "The Design of CMOS Radio-Frequency Integrated
> Circuits, 2nd Edition, Cambridge University
>
> Homework
>
> JAL> Neither link works as posted. Try these instead:
>
> receiver:
>
formatting link
>
> transmitter:
>
formatting link
>
> My apologies for posting incorrect links.
>
> Steven Cooke
>
>
formatting link
>