Sorry! Lapsus keyboardii! Of course, 995 Hz not kHz! It was not a MW transmitter!!! Brian On 08/05/2011 13:47, Brian Ellis wrote: > Sorting out some old junk, I came across the first object I ever made > with a transistor, dating back to 1955. In order to calibrate some > telecomms gear in the field, I needed something portable. I made a > couple of signal generators producing 0 dBm into 600 ohms at what was > then 1 kc/s (now 1 kHz). These were 100 x 64 x 25 mm, including a 4.5 V > "flat" battery. This was before PCBs (or even transistors) became > mainstream, so the wiring was component to component. The transistor was > a point-contact germanium type, made by a company in Newmarket, that > cost a fortune, at the time (£20, if I remember correctly, half a > graduate engineer's monthly salary!) and was so delicate that they > failed if you looked at them hard. They had to be soldered in at the end > of 30-50 mm leads with special short-circuiting heat sinks clipped to > the wires. Looking at it, I was astounded at the appearance of the > solder joints, somewhat corroded, but VERY ugly. Then I remembered the > 100 W soldering irons we were using at the time, bare copper chisel bits > from about 8 mm diameter stock, filed into shape several times per day. > I thought it was a wonder I could solder anything so small with those > tools. Of course, thermostats were not even thought of in those days. > Temperature? Goodness knows, it was never measured, but I would > guestimate close to 400°C. > > I know this device was used in several countries and my colleagues and I > used them for several years. The brass case of the survivor is bashed > and the paintwork reflects a hard life. > > I thought to myself that it was undoubtedly buggered. I couldn't find > the right battery locally but asked my daughter to bring one out from > Switzerland at her next visit. I could see the switch was physically > broken, so I short-circuited it. I then reassembled it with the battery > and found that IT WORKED! I made up a load of a 560 ohm + a 39 ohm > resistors in series. Checking the output, it was amazing: 0.775 V RMS, > spot on 0 dBm at 995 kHz!!!! Not bad after 56 years! Maybe rotten, ugly, > uncontrolled, overheated, solder joints are not so unreliable as one > would imagine! > > Brian > > > ______________________________________________________________________ > This email has been scanned by the MessageLabs Email Security System. > For more information please contact helpdesk at x2960 or > [log in to unmask] > ______________________________________________________________________ > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 16.0 > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > For additional information, or contact Keach Sasamori at [log in to unmask] > or 847-615-7100 ext.2815 > ----------------------------------------------------- > ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 16.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------