HFU HF Underground
Technical Topics => Equipment => Topic started by: Deffy on March 23, 2015, 1118 UTC
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I own a Sony ICF-SW7600GR and looking for homebrew antenna options for this. For Shortwave the manual tells me to use the built in whip antenna and I can clip on a random wire to improve signal if desired. There is an External AM port (1/8") which is for the AM Broadcast, MW, and LW bands. For the External AM Port the manual basically says to only use approved antennas since the port also supplies power for the antenna.
Am I really stuck with proprietary antennas or clipping random wires to the whip antenna or is there something else I can do? Most homebrew plans assume a Coax input which obviously this radio does not have.
I know buying a better rig is an option but don't have the cash flow at the moment.
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Hello
I heard Indonesia here in Italy on the tropical bands only using the 7600 whip so a longer antenna is not really mandatory. Anyhow there is no problem using the 3.5 mm antenna jack. Only keep in mind to insert a capacitor on the antenna wire to avoid short circuiting the antenna power supply.
Giovanni iz5pqt
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The effectiveness of the built-in whip really depends on the construction of your house. Metal siding or brick will reduce the signal, for example. I would think your best bet is to clip a length of wire to the whip antenna using an alligator clip. Place no more than 30 feet of the wire outside your dwelling if you can. Generally with portables, any more than that would only increase the chances of signal overload and cause the receipt of spurious signals. I'm not familiar enough with the 7600 to know if it has an attenuator switch (like my Sony 2010). But if yours did, that would be helpful to reduce the overload. Another possible solution is the use of a band preselector. A model such as the MFJ-1046 would be one choice. I used to use a preselctor with my 2010 at one time, and that typically removed all phantom signals, and allowed me to use a random wire antenna mounted outside. I now use an Icom R-71A, so overload with an outdoor antenna is not an issue. Hope this helps.
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Well the house is a simple wood frame with vinyl siding but I did notice there is some metal foil between the siding and the house. Reception on HF is pretty bad, in fact there are only a few spots in the house where I can some what hear something. The SW7600GR does have an attenuator switch and a dial for adjusting the amount of attenuation.
I have gator clips but need to get some wire, any gauge wire I should pick up?
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I wouldn't think the foil would attenuate the signal all that much. That said, you'll still enjoy better reception by placing an antenna outside the house. The size of the wire you choose is not that critical. Anything in the range of 18 to 22 gauge should be OK. What I've done for many years is to take at least a 30 foot length of copper wire with egg insulators on either end, mount it outside my house, and connect to the receiver using a shielded coax cable (rg-6 for TV is OK). What you do really just depends on how fancy you want to get. Having an adjustable attenuator on the radio should help to avoid overload. Just keep in mind that everything, including your target signal, is being attenuated at the same time.
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Of course I listened to Indonesia outside the house. I just meant that the set is very sensitive, so it won't need a long antenna. Any wire gauge will do.
The important issue is the noise level. You should first compare the reception and the level of noise inside and outside the house using the whip. Also, try to move away from the house to see the general background level in the area. An external antenna will help if the outside reception is better. If you get a lot of noise inside you should use a coaxial cable to go from the external antenna to the radio (use the 3.5 mm jack in that case) otherwise the noise will be picked up by the piece of antenna wire inside the building. In that case you have to take some precautions I can explain to you, but first check the reception outside.
Giovanni