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Looks very interesting...I shall look at it after the holidays! Thanks Phil...

Gianfranco

2.2. NARROW BAND PRE-SELECTORS - TUNEABLE BANDPASS FILTERS @ 3.8 MHz Using a double gang easily self made variable capacitor, our system Qu rises to 400 or better and the new parameters are as follows: Qu=400 Ql=80 Insertion loss Il=2 dB/single tuned & 2.8 dB/double tuned. Coefficient of coupling p...

2.1 NARROW BAND PRE-SELECTORS - TUNEABLE BANDPASS FILTERS @ 3.8 MHz In the frequency range 3500 - 3800 KHz, Iron Powder material N2 toroids, have measured ( by me) Qu's of 400 or higher. We must now consider the problem of the tuning capacitor. Using an inductance of 50 uH, easily obtainable with a...

Yes I still have the external SICSI drives and the Iomega storage chartridges with lots of data & design software, which can be useful from time to time. in the eighties and for all the nineties you had to use MAC for serious work. Windows software was still in toyland, with just about three crashes...

Hi Phil, We now have to consider how much strong is "strong" and " and how much "far" is far. If you look here: https://www.sdrplay.com/community/viewtopic.php?f=5&t=3926 you see that for the RSP Processor 2° order and 3° order effects start at a level of -35 /-40 dBm of the unwanted signal. These l...

Well, now the post by Ian1951 after misteriously disappearing, has re-appered and I can reply. The problem of dry contacts becoming insulated in the long run is caused by oxidation. In relays switching small or negligible currents and exposed to the atmosphere, this used to be a serious problem in t...

Hi Phil, The dilemma about selectivity Vs. insertion loss is not really a dilemma, if you carefully consider the data at your disposal. 1) The minimum detectable signal (MDS) of the RSP2 @ 10 MHz (given its rated Noise Figure) can be safely set at -120 dBm. 2) You now have to give a figure to your a...

Phil, is this below the WSPR signal on 10,138.700 ? It has a kind of wobbly modulation.

The Mac in use is the SE30, but I have quite a collection!

You did not say if you wish me to do the xtal filter and where.

Cheers,

Gianfranco

Must switch off, or the laptop will blow up with heat!

I think I have hallucinations here..... one hour ago I saw a post by Ian1951 warning about dry relay contacts (not the case here) and I wished to reply and now........ZIP BANG the post has disappeared! Must be the heat playing tricks on me: I have 39 °C around me and the air out of the cooling vent ...

Hi Phil, good for you you are in wintertime, here we are roasting at 38 °C, going to 40° and still some do not believe in climate change! Next week I am leaving for Sardinia: it is sailing time now and I will somehow be off the Forum for a while. I really need to do that and assess the results with ...