LF: Re: Re: Re: Re: 475 kc Exiter /JUMA

["mal hamilton" <g3kevmal@talktalk.net>]

I think it very helpful for him to save money since he is building from a KIT he may as well be building from the junk box at no cost,  a good radio amateur approach. G4JNT has built a 700 watt rig from the junk box and described many times also uploaded to this group.

I have built several rigs from the junk box and use LOPT transformers from junk TV sets at no cost.

All radio amateurs in discussion while having a QSO describe what they are building and using.

Others should be encouraged to be positive and built where possible and CW is a big advantage under marginal propagation conditions.

I wonder why you have a problem with my experiences and achievements?? in fact one of your own German amateurs DK7FC builds his own equipment and has great success with world wide communications on LF. He publishes information frequently about his experiments and achievements. Do you have the same problem with his emails.

Are you trying to suppress LF/MF experimenters describing their experiences and success??

de G3KEV

 

 

 

----- Original Message -----

From: Clemens Paul

To: rsgb_lf_group@blacksheep.org

Sent: Thursday, May 31, 2012 5:09 PM

Subject: LF: Re: Re: Re: 475 kc Exiter /JUMA

Mal,

 

in which sense do you think is your mail helpful for Uwe or other list members?

Instead of ad nauseum repeated emails from you bragging with your home brewing

and CW skills,your antennas,etc.we would like to see mails from you containing

some possibly useful information for the list members

 

 

 

73
Clemens
DL4RAJ

----- Original Message -----

From: mal hamilton

To: rsgb_lf_group@blacksheep.org

Sent: Thursday, May 31, 2012 6:08 PM

Subject: LF: Re: Re: 475 kc Exiter /JUMA

Uwe

I could build the same specification 60w rig for NO cost out of my junk box hi. The rig seems expensive for a kit and only 60 watts

The Ropex 130 w rig for 136 Khz was less than £200 new and already built, even that was expensive. I built a 1Kw rig for almost nothing out of my junk box and still have after many years.

I also have a couple of MF marine transmitters suitable for 500 lying in my garage !!

de mal/g3kev

 

----- Original Message -----

From: Uwe Wensauer

To: rsgb_lf_group@blacksheep.org

Sent: Thursday, May 31, 2012 3:10 PM

Subject: LF: Re: 475 kc Exiter /JUMA

Hi,

here is the  bill for my new JUMA TX500

 

Subtotal: 299.00€
Postage & Packaging: 26.00€
Tax: 68.77€
Grand Total: 393.77€

 

I´s by the way the 3rd kit I am building ( all bevore where built for others ..) but thats for my self ..

 

Uwe DK1KQ

 

From: Stefan Schäfer

Sent: Thursday, May 31, 2012 1:43 PM

To: rsgb_lf_group@blacksheep.org

Subject: Re: LF: 475 kc Exiter /JUMA

 

Hi Clemens,

Oh, OK. But anyway it was a very good hint to mention the JUMA 500 TX since it leads me to the CMCD design and this paper which nicely describes the problem of the VMCD desgin which i am trying in my first tests.
The output C of the FETs is the problem. Since i want to have a relatively high power (100W) at 12V DC, the primary impedance is very low. So i have to use FETs with a very low on-resistance, ideally as low as possible of course. To find them is no problem (e.g. IRFP4368), but the output C is much to high then. I tried a IRZF48N (2 of them of course) as a compromise between RDSon and Cout but am just getting 60% efficiency at 70W in the first attempt. That's not acceptable for a /p PA that has to stay compact, i.e. without a big heat sink and/or a fan...

The basics are well explained in this paper, makes fun to read :-)

73, Stefan/DK7FC

Am 31.05.2012 13:08, schrieb Clemens Paul:

It costs 300 Euro which is not to much.

Unfortunately you have to add 23%VAT tax within EU and shipping costs
which I estimate to 30-40 Euro.
So we end up somewhere around 400 Euro.
Interesting kit,though.

73
Clemens
DL4RAJ

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