|
Title: Antenna Tuner for 160 Post by: K9ACT on April 21, 2009, 12:42:50 AM I have a Heathkit 2040 antenna tuner and suddenly got the bug to operate on the 160 M band.
I modified my 810 rig to do 160 at about 225 W carrier but can't get beyond the dummy load because the 2040 does not cover 160. It seems intuitive that adding more L and/or a padding cap or two would be rather simple to implement. Unfortunately, I do not know enough about tuners to come up with the numbers and what goes where to do this. Anyone care to help me here? Has this been done before? js Title: Re: Antenna Tuner for 160 Post by: K3ZS on April 21, 2009, 09:49:00 AM Double L and double C is the rule of thumb. You might be better off building a new tuner for just 160M. Check out the K1JJ tuner on this forum, not sure where it is, do a search.
Title: Re: Antenna Tuner for 160 Post by: W8ACR on April 21, 2009, 10:08:13 AM What kind of antenna and feedline? Two capacitors, two inductors, and two hours of time will get you a great tuner for open wire line to a dipole. I can send you a photo of the one I built. It will tune both 160 and 75 meters. The circuit can be found in any of the 1950's ARRL handbooks.
73, Ron W8ACR Title: Re: Antenna Tuner for 160 Post by: WQ9E on April 21, 2009, 10:48:46 AM Jack,
I use a homebrew reversible L tuner here. Basically a roller inductor out of a Gates broadcast transmitter and a 1,500 pf vacuum variable coupled with a switch selected 500 pf padder. I use one "tap" switch from a BC-375 (available cheap from Fair) to switch in the additional padder as needed and another tap switch to choose on which side of the inductor the capacitor is used. The L is basically a low pass filter which never hurts with vintage gear. I have used it on 80 through 10 with the Desk KW and other gear and on 160 with a Drake 7 line including the L-7 amp. I built an identical one for the "DX and contest" position in the barn and that one has been used on all bands at the full legal limit without issue. Rodger WQ9E Title: Re: Antenna Tuner for 160 Post by: Opcom on April 22, 2009, 11:43:30 PM Mine seems to have enough L, but not enough C. The padder is a good dea.
Title: Re: Antenna Tuner for 160 Post by: K9ACT on April 23, 2009, 12:53:13 AM I took someone's advice and dug into a 1973 Handbook and found the solution in my junk box. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Connecting together the shack ends of the feed line from my 80 meter dipole turns it into a top-loaded vertical. All that is required to match this to the transmitter is about 500 pf of capacitance. I used a 1000 pF loading cap and an SWR bridge and got 1:1 with about 500 pF. Works fine but I will be putting down some radials as soon as the wire arrives. It may be a compromise antenna but it gets me on the band. Thanks for the suggestions, js |