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Interested in 2 boards.

Daniel KB3MUN

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What’s the filtering range on the BCI. I used the same board but I made a BCI that allows for 160m

Rotary switch isn't a bad idea. Here's my AGC installed inline with a BCI filter. I did tack header pins to the board as I cannot stand soldering wires direct. Seriously contemplating bringing the RF gain pot up front as I've got a 10K/1K concentric pot in the parts bin...

Nick,
Me Too!
Jay

--
Adrian
VK2ALF
Cooma, Australia & Otep??, Estonia

The last one, the active antenna is the so called mini-whip and makes sense. There are a few different designs with different transistor. It has to be installed very well, not necessarily very high, but needs a good ground. Otherwise you receive lots of noise. About fractional antenna, I don't know although I have heard about them 20y ago. For receive purpose I have been always impressed by the MTA passive antenna by RF-Systems. Maybe because it is installed well high on the roof but I still am amazed how it works for being just a 7 feet high vertical, from LF to 30mhz. So for receive there are good alternatives.

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Hi,

It is common wisdom that the size, or capture area, of an antenna goes hand-in-hand with its efficiency in radiating or receiving radio waves.

This was just mentioned in an ARRL newsletter. A?piezoelectric VLF antenna.



So does this try to work by generating an extremely high voltage to try to pump energy into the high impedance that a fractional wavelength antenna, of conventional wisdom, would have into free space? Like a mini solid state Tesla coil, without all the wire and corona discharges?

How about this. I read an article about efficient fractional wavelength antennas for a few hundred MHZ and up based on arrays of "Split-ring Resonators". Don't remember where the original article was, but here is the Wikipedia explanation. If you don't mind soldering together hundreds/thousands of loops of wire, maybe it would work at HF :)



And finally, more down to earth, here is an antenna I am going to try out as a receive only antenna, that goes counter to the capture area principle.



I can understand how an active antenna with a high input impedance pre-amplifier with a little 2 inch piece of metal for the antenna element, might work acceptably in spite of the lack of efficiency, as a receive antenna. Although I won't count on this as my primary DX antenna. I'll likely use it a a secondary antenna for USB SDR receiver.?

The first two antennas seem to groundbreaking, assuming the reality matches the perception given by the claims.

Tom, wb6b


?

First off, do the daughterboard relay trick to help with the existing low pass filters.

Then consider adding individual bandpass filters (they make them for contesters and there are design papers on the ARRL site i believe) to help with other issues.

Fix the close-in spurs by dealing with the 45 MHz IF (the version 5 board may be a better choice)

Then take some well-behaved amp board and pair it with some heavyduty output filters built for it as well. -- or just buy something already out there on the market (but then it will be in a separate box)

I've finally gotten my Siglent Spectrum Analyzer but I haven't yet put it on my prototype V3 duaghter-board-modified rig -- too busy working to solve a noise problem at the local EOC where the spectrum analyzer has been HUGE in documenting the problem.

However, one think I *did* find was that my Heathkit cantenna attenuator tap was NOT comletely "level" -- it attenuated higher frequencies LESS -- so it made the receiver S-meter tests that I did, appear worse at higher harmonics than reality.

I'll get the spectrum analyzer on the board sometime...and find out if I should have used tiny coax for the input/output instead of plain wire like I did. I still need to replace the toroid that I destroyed with clumsiness in my first efforts to hack the traces.

Gordon


________________________________________
From: [email protected] <[email protected]> on behalf of Matthew Pitts via Groups.Io <daywalker_blade_2004@...>
Sent: Thursday, May 2, 2019 9:34 PM
To: [email protected]
Subject: [BITX20] RF Amplifier suggestions

Good evening,

I'm looking for ideas as to some sort of integrated RF amplifier for this, preferably one that has additional filtering to make sure the spurs are fully dealt with.

Matthew Pitts N8OHU
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

Good evening,

I'm looking for ideas as to some sort of integrated RF amplifier for this, preferably one that has additional filtering to make sure the spurs are fully dealt with.

Matthew Pitts N8OHU
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

I guess I've had enough fun with this radio and now it's time to move on.? I'm selling by UBITX V.3 in an Apache case. There is space for the mic and a battery pack to sit when the case is closed. The mic and PTT switch are mounted in an old BaoFeng mic housing and it works well.? My paint job is not the best but you could say it's a great concept... I've made quite a few mods, but that doesn't mean the new owner needs to stop experimenting.? You can see my list of mods on this thread:?/g/BITX20/message/63243?
?I was never able to get the function switches to program, so that's one thing you could work on. I'm asking $140 via postal money order or PayPal.? I will also include all of the original parts I can find in case you want to try to restore it to near original configuration, although it works pretty well as it is.??

Definitely sounds like your just getting leakage/pickup on that pin. The inputs are considered "High impedance" and will only drain slowly so if there is a lot of energy floating around (and its a ubitx we know there is!) it will definitely pick up some of that and store it in what little capacitance the wires provide. The fact that is is consistent is amusing at least :)

-- Tim Keller - KE2GKB

I remember seeing that, too. If memory serves, use those for your min/max values when setting smeter break points in the mem manager. With the meter installed, you should get a fairy stable number based on the freq. I think it took a bit of time to get the break points in the ball park. I'm on a full agc on one rig and the stand alone analyzer on the other...so, I can't check for you.