Hello all I apology for the off-topic. However I know that this group is attended by very experienced gents, mainly from the UK. I found these two tubes in the junk, see the attachment. I spent quite
Thanks all for your responses. The valves looked NOS therefore I searched for specs to be able to make a small PA with them. Now it looks I will put them back on the shelf for another twenty years in
Hello Marco, You are so kind. Thank you very much. My tubes look exactly like 4B/551B(D). I will measure the dimensions to be sure as soon as I can. It looks convenient that the filament voltage is t
Hi all, My intention is to build a small transmitter up to some 10W for 136 and 505 kHz, this time not the D class, but B or AB class. I think of employing AF amplifiers such as TDA2003, TDA2030, or
Hello all, Thanks all for your comments, it helps. I can't recall that anybody would ever mention the possibility to change serial connection of the coils of a variometer to the parallel one. If the
Hello Ha-Jo Thanks for your suggestion. My transmatch woud be used mainly for RX, however, I still believe that a tuned antenna is better than detuned one. At least it is a good preselection for RX.
Hi all, I want to make a small transmatch (RX, TX up to 10 Watts, or so) to tune LW 41 m (or smaller T-ant) in the range 50 ... 550 kHz. I am not too good in theory... but I believe that the most eff
Hi all, I have made a tunable up-converter for VLF, LF and MF. Nothing ground-breaking, perhaps, but maybe a little inspiration for some. I have compared the result with a professional receiver RFT E
Hello Graham, I use DDSv4: http://www.rmt-tech.com/Products.html I use it in my up-converter: http://ok1fig.nagano.cz/UC5695/Uc5695.htm I was so happy with it that I purchased two units more for the
Hello all, Short of a thick litz wire? I found this item on eBay right now: http://cgi.ebay.com/Litz-wire-660-46-for-crystal-radio-coil-Loop-anten-60_W0QQitemZ160360053886QQcmdZViewItemQQptZLH_Defaul
Hello all, I wonder where the following web disappeared: http://www.picks.force9.co.uk/index.htm is it just temporarily unavailable, moved to another address, or canceled totally? It was a great sour
Hello all, Too lazy to make variometer? LF/MF-related items rarely appear on eBay, here comes one: http://cgi.ebay.de/Variometer_W0QQitemZ110447622031QQcmdZViewItemQQptZDE_TV_Video_Elektronik_Funkger
Hi Lowfers, I looked for some Q-codes recently and one of them struck my eyes. Do you know what QOA means? It means "can you/I can work telegraphy on 500kHz". 73 and have a nice X-mass, Petr, OK1FIG
Well, I am not sure that it is a good news, in fact. So far only people that were able and willing to build their own TX's (Ropex First was not a hit, was it) were on the band. And the ham-spirit exi
Hello all, I recently purchased Siemens Pegel Messer (selective level meter) D 2006. It was a quick casual purchase, extremely cheap. Unfortunately no documentation was available along. I have search
Hi all, I also heard HE3OM, at 14:15 UTC on Jan 30rd, RST 599, on 137.32 kHz. Very strong signal, indeed. 73, Petr, OK1FIG JO80dh From: [email protected] mal hamilton Sent: Sunday, January 30, 20
Hello Roelof, It is an honour for me to have the answer directly from the author of this little magic thing. I didn't realize that you are on the group as well. How long did it take you to develop it
Hi all, I have made a Mini-Whip antenna. I was just curious whether it can actually work or not. I tested it in a rf-quiet rural area. The antenna was drawn up to about 13 m, see the attached image.
It is perhaps not so critical on LF and MF. I did it like that anyway: http://www.nagano.cz/~ok1fig/MiniLoadingCoil/P1171705.JPG http://www.nagano.cz/~ok1fig/MiniLoadingCoil/P1171705.JPG 73, Petr Fro
