Recent content by PsiDOC

That's excellent news Sonoma. I had a very good idea it was correct. I just couldn't find any application data to work from. Seeing as you're here and I cannot find any application information for the EN1230. Can I ask you what is the size resistor you use to the +8v tx line? I am guessing 3.9 -...

No robb. The EN369DR I have proved as above is correct in the driver section, and looking at the EN1230 if you were to bias it with a 3.9k resistor to the 8v tx power line it would bias properly at 3.66v. Whilst I have not found any radios that use an EN1230 for mosfet biasing from the factory...

Ok let's run with that. Final biasing example with R2 in the EN369FN at 100k ohms First we calculate the current: current total = transmit line voltage / (RV11 midpoint + R239 + [our new R2 of the EN369FN]) = So current total = 7.4 / (10000 + 10000 + 100000) = 7.4 / 120000 = 0.00000616A...

Hi all. Was playing with mosfets over the weekend when I noticed something a bit strange going on with the information on CBtricks with regards the EN-369FN. Whilst the information below does contain some maths and Ohms law it does clearly prove that the EN-369FN drawing and in particular the...

Thanks for that guys. I know those drawings very well. What I need is actual real world readings. I have a gut feeling that one of those drawings is incorrect, however I NEED the resistance reading from the EN-369FN to coroborate my evidence.

Does anyone have an original EN-369FN laying about in their parts box? If so can you kindly put a multimeter across it both ways (positive to + and negative to - , then the other way around) and tell me what the resistances are please? There is a reason for this and If I am right I'll reveal...

Morning all out in DX land. Another update for you. A second homebrew GM has now been born and not made by me may I add. The constructor, eddie (location unknown, but it's somewhere cold as he was testing it in temps of -21c!) used the as built dimensions I posted a couple of pages back and...

I couldn't agree more Northern. However the design I have used here uses RG58 for the capacitor as well hence I recommend 120 125 watts maximum for the RG58 based design I have posted. Psi

Noise off the ac compressor motor is likely to be your biggest problem. Only way to find out is to chuck an antenna up there. Re coax. Buy the best you can for your budget. Lower loss the better. Psi

... and hence why I wouldn't run more than 120 watts into the antenna using RG58. Psi

Hi Radiooman. That is exactly correct. I set the meter to 50% of full scale when testing with the RG58 stub at 25 watts. Then after changing the stub this reading increased to about 85%. I am sorry I cannot be more accurate than that. The field strength was a last minute idea so not calibrated...

And here for your viewing pleasure is an as built diagram with all the relevant numbers and materials used. ;) Psi

Another follow up. After doing some research, using RG58 for the matching stub was a big no no - Thank you Shockwave for pointing this out - it's appreciated. :) According to the calculations I have done approx 40 - 45% of the power being fed into the antenna was being lost in the stub. Not good...

That's what I wanted to hear. This means I have the bits I need to hand so no waiting time for delivery. Already calculated the stub length. W103 vf = 0.85 so it's 85*0.85 = 72.5 cm or there abouts. Will cut at 75cm and trim to suit. I love it when a plan comes together! Si

There's a lot of naysayers and self proclaimed experts about Homer. However you never know till you try. It's quite a simple antenna. No fancy tuning circuits or coils to get wrong, just the matching stub which it seems I need to develop further. :) I get a kick out of making antennas out of...