Re: LF: Re: 137 grabbers

[Daniele Tincani <danieletincani@yahoo.com>]

Hello Stefan

 

@Daniele: Nice to read you also want to join in on LF! BTW VLF is not forgotten here, i want to come back in September. But want to have the LF system ready for the DX season and wat for lower QRN on the Dreamers Band...
You don't have a licence and cannot TX? Wouldn't it be worth to learn for a licence for that reason? :-)
And have you done further tests on sferics and so on your remote VLF QTH? Any news?
Just got re-fascinated by John/F5VLF about the earth antenna stuff and want to do more experiments on that antenna again but LF improvements are very time consuming! But i have holidays now :-))) I am curious how the earth antenna performs as a RX antenna on 137 kHz (directional pattern and gain and noise). As a TX antenna i will be to lossy i think and its not worth the effort carrying 100s of kg of batteries on the hill for doing some CQ calls that are not answered....

I'm afraid that I have caused a little misunderstanding :-) I'm not planning to join LF as a tx station, I think that I will remain a radio listener with some special interest for low frequencies (for example NDBs). Probably I could get a licence with a reasonabe effort (after all, I still have a degree in electronics), but frankly speaking it does not attracts me very much to tx. As for VLF, my conclusion has been that rx conditions at my QTH are such as to suggest to give up with further tests. Now I'm building this wideband loop (with the M0AYF-derived amplifier) hoping it will match well with my SDR receiver as a wideband rx system, at least at MW and lower HF.

 

Best regards

Daniele

 

From: Stefan Schäfer <Stefan.Schaefer@iup.uni-heidelberg.de>
To: rsgb_lf_group@blacksheep.org
Sent: Sunday, August 14, 2011 8:03 PM
Subject: Re: LF: Re: 137 grabbers

Minto, Daniele,

@Daniele: Nice to read you also want to join in on LF! BTW VLF is not forgotten here, i want to come back in September. But want to have the LF system ready for the DX season and wat for lower QRN on the Dreamers Band...
You don't have a licence and cannot TX? Wouldn't it be worth to learn for a licence for that reason? :-)
And have you done further tests on sferics and so on your remote VLF QTH? Any news?
Just got re-fascinated by John/F5VLF about the earth antenna stuff and want to do more experiments on that antenna again but LF improvements are very time consuming! But i have holidays now :-))) I am curious how the earth antenna performs as a RX antenna on 137 kHz (directional pattern and gain and noise). As a TX antenna i will be to lossy i think and its not worth the effort carrying 100s of kg of batteries on the hill for doing some CQ calls that are not answered....

@Minto:
Am 14.08.2011 19:33, schrieb Minto Witteveen:

Above 10 MHz the gain drops off rapidly, it is nearly useless at 14 MHz. a -77 type would be much worse there I think.

Sure. I just talked about LF now. I read the -43 type is suitable for 40...400 MHz, at least this is said in the catalog...

As for the Q: I did a comparison between an FT50-43 and a 14 mm 4C6 (for my 137 KHz low-pass filter, see my website). The Q of the FT50-43 coil was abt 50, the 4C6 – with a lower Al - was 140 !!

Interesting! 140 at which L? I am searching for ferrite cores to achieve a high Q on LF, in the range of 100...1000uH. Where can i get these cores? At RS? Where do you buy them? They are usually samller, cheaper and easier to handle than pot cores.

BTW what do you think about a ferrite RX antenna for LF? Now i'm opening an older discussion i expect ;-)

73, Stefan/DK7FC