Hi All

I am struggling to sort out an easy circuit to turn on 1, 2, 3 or 4 relays. I need to switch the relays in order to bypass loading coils on a new antenna that I am playing with. Imagine four coils in series and four relays parallel to them, each coil needs to be bypassed in turn with a single rotary switch. I need to bypass 1, 2, 3 or all 4 coils but I can't work out how to do it. Please help.

Thanks

Jon

Without drawing it out or thinking too hard, I'm thinking quick and dirty would be to use steering diodes. Common all the relays on one pole. Get a 4 position rotary switch fed with positive, position 1 feeds relay 1 through a diode, position 2 feeds relays 1 and 2 through two more diodes, etc.
10 diodes in total.

hmm, 5 position rotary switch, as position 1 energises none of the relays

Looking at your thread on TM1 http://www.transmission1.co.uk/viewtopic.php?f=34&t=39470 I wondered if you were aware of a number of other commercial antennas that follow the same format as the one you are intended to produce and sell?

Although you slated the Pro Antennas version for being single band, others that are multi-band are the N6BT "I" Vertical Dipole http://www.n6bt.com/n6bt-Bravo-comparison-I-style-1.htm and the TW Antennas "Transworld Vertical Dipole" http://www.twantennas.com/products.html.

I'm puzzled too that someone sporting a G2 call sign can't figure out such a simple switching problem themselves

I haven't done any electronics in years and have been having a lot of memory problems even though I'm only 44 meaning that I can't remember much about the RAE or my electronics BTEC. It's strange that I designed a lovely circuit using an LM3914 bar graph driver but was having trouble with simple diodes. I've sorted it out now I think with the circuit below. Well done for finding that post on Transmission 1, I stand by what I said there. If I get it working I intend to sell the antenna as cheaply as possible rather than the inflated over priced antennas that we have on offer in the UK.

I was originally M1CCK in 1997, then M0BQQ in '98 then when my uncle passed away in '99 I inherited G2FHF. I'm now a busy farmer and just surviving in this business has pushed most of my electronics knowledge right out of my head.

Cheers

Jon

Thats pretty much what I was thinking, but you need a 5 position switch to allow a no relay selection. Or just an off switch.

Bit of a waste, you can have an 8 pole switch and 8 different inductances, why only 4?

Add a couple of remote capacitors, and you will have a full tuner for little extra effort.

Add a simple pic circuit, and it can be automatic.

Though I would assume your coils would be in the centre, and not at the end of the antenna.

Or simply if the four series inductance coils are of four different "L" values, (not sure of your design), then feeding the relays with simple binary logic would give you 16 different switchable inductance values, ie 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111.
Also don't forget reverse polarity diodes across the relay coils, if you want to eliminate large "clicks" on the RX, and consider RF chokes/ferrites/screened control cable, for the relay feed wires, as you don't want RF induced into what might be a long run of control cable, ending back up in the shack.