Grundig Satellit 750 Antenna

[Harlock]

I'm getting a the Satellit 750 as an upgrade to my current Kato SW receiver, but I'm a little confused on what I should be doing with the Red & Black High Impedance external antenna connections for this radio. I know that the RED will be my receive and the BLACK will be my ground, but how necessary is it to have a ground wire connected for a receiver? I only wonder because my current SW receiver has an external antenna jack (3.5mm) and came with a 25' length of of wire, and works great.

There's also a BNC coax connection on the Sat750 which I intend on using eventually, but at the moment I have a couple of spools of 25' wire I can use, and am hoping I can just pop those into the Red and Black high impedance terminals. Would be even better if I didnt have to use the ground wire, but I'm sure I'm overlooking something.

A third possibility I have is to connection one of the 25' wires to an alligator clip, and attach it to the built-in whip antenna. I'm just not sure if that is going to be more than the radio is expecting to receive, and create station bleed.

Any help/input would be appreciated - thanks!

 

[WA8ZTZ]

As to whether or not to use a ground, you will have to experiment and find out. In some cases, you may find that the use of a ground may introduce noise. All grounds are not created equal... a ground in sandy soil will not be as effective as a ground in, say, damp clay.

The BNC connection is a 50 ohm connection and when using a random length of wire antenna here better results will be obtained by using a 9:1 matching device.

Don't worry about the antenna overloading the receiver, the 750 has attenuators that you can switch in if necessary.

Be aware that for AM BCB and LW that the external antenna connection is the mini jack on the back of the rotatable loop on top of the radio.

Good luck your 750, mine has given me many hours of enjoyable listening.

 

[ka3jjz]

Try to avoid clipping any wire to the whip. If the slightest bit of static electricity builds up and you touch the whip, you may very well render the radio deaf. There's likely to be an amplifier at the base of the whip that would summarily get blown. Try to use the spring terminals and the BNC connector before doing this.

Mike

 

[devicelab]

Ideally you want to use the BNC connection. Here's an antenna that WA8ZTZ is suggesting:

Par Electronics EF-SWL End Fed Dipole SWL Antenna. Par EF-SWL.

You just have to buy some coax and a BNC adapter.

If you have the space this would likely a better antenna but it requires A LOT of space:

Alpha Delta DX-Ultra Antenna

Here's a shorter version by the same company similar to the PAR antenna:

Alpha Delta DX-SWL Sloper Antenna, dxswl

 

[ka3jjz]

<snip>
Here's a shorter version by the same company similar to the PAR antenna:

Alpha Delta DX-SWL Sloper Antenna, dxswl

There are significant differences between the 2. The PAR has a dual wound transformer / matching network (that has various methods of connection to ground) at one end, while these antennas have a matching stub. And the full size version of this antenna covers MW, while the PAR really doesn't (yes, it will work there, but the transformer really isn't set up to cover MW)..

Still, it's hard to argue against the assertion that both the PARs and the Alpha Deltas are fine antennas on their own.

Loops are really the weapon of choice on MW and below because stations (and sometimes interference sources) can be nulled out, revealing stations you couldn't easily hear on a wire. Still, for wire antennas, these 2 are pretty good ones. It very much depends on what applications you will use for the antenna - are you interested in HF, or HF and below? Mike

 

[WA8ZTZ]

FWIW, the PAR EF-SWL antenna is now being manufactured by LNR. The LNR label on the antenna rates it for .3 to 30 megs. In actual use with the Satellit 750, the EF-SWL out performs just a simple random wire antenna from LW through HF.

That said, there can be better choices for LW and MW. As mentioned, a loop is in many cases more effective than a wire antenna. However, if you have the real estate, multiple beverage or KAZ antennas can produce amazing results.

 

[ka3jjz]

Unless LNR has redesigned the toroids in the matchbox, it's probably a stretch to think that it will work on LW, much less MW. The last I heard, the toroids start getting lossy the lower you go below 2 or 3 Mhz, but that might have changed. And the length of the antenna itself is just too short to support going that low anyway with any efficiency. Still, it's probably the best compromise antenna out ther of this type. It's certainly been out there longer than its competitors.

Mike

 

[WA8ZTZ]

Unless LNR has redesigned the toroids in the matchbox, it's probably a stretch to think that it will work on LW, much less MW. The last I heard, the toroids start getting lossy the lower you go below 2 or 3 Mhz, but that might have changed. And the length of the antenna itself is just too short to support going that low anyway with any efficiency. Still, it's probably the best compromise antenna out ther of this type. It's certainly been out there longer than its competitors.

Mike

Performance on LW and MW would depend primarily on what material they are using. The trick is to get coverage all the way from LW through HF. Whatever they use, it does a good job on LW... have received the DX to prove it... British Columbia, Nunavut, Cayman Islands, Puerto Rico, Greenland, to name a few, while not sacrificing HF performance.

The EF-SWL is as you say probably the best compromise of its type. If you can have only one wire antenna and want to cover LW through HF, the PAR EF-SWL, now by LNR, would be my first choice.

 

[Harlock]

Wow, thanks so much for the great suggestions. I've gone ahead and order a couple of 9:1 baluns to experiment with making a receiving antenna or two, and have also ordered a pre-made 80' longwire with 9:1 balun & coax to get me started right away.

As some of you have mentioned, the 9:1 will hopefully improve my listening experience greatly enough without the use of a ground, however so many claim that the ground will make it even better.I'll likely give it a shot without the ground at first, and see what I notice between the unun shortwave dipole I am using currently, and the new 80' longwire w/ balun.

One more question, for receiving purposes only, and to simply reduce common mode noise, how necessary is it to have a ground wire connected to a ground rod 8' deep? Would only a foot or two do perhaps? Or just having the ground wire from the balun lay across the ground for a few feet?

 

[ridgescan]

For what it's worth, my PAR EF-SWL well-grounded 9:1 trans box to a 100' wire has received DX in LW well into Canada, in MW as well, does very well in HF and can receive CHP in 42-43mHz even into Sacramento. it is up 50'.

 

[WA8ZTZ]

One more question, for receiving purposes only, and to simply reduce common mode noise, how necessary is it to have a ground wire connected to a ground rod 8' deep? Would only a foot or two do perhaps? Or just having the ground wire from the balun lay across the ground for a few feet?

Generally speaking, the more ground rod(s) you have, the better. For electrical work, a 8' ground rod is the minimum requirement. In your case, "for receiving purposes" how much of a ground rod needed will depend on the soil conductivity. You will have to experiment and see.

If you suspect a common mode noise problem, a common mode choke may be necessary.

btw... if your antenna installation is of a permanent nature then lightning protection along with the necessary grounding becomes another consideration... the National Electrical Code Article 810 should be consulted.

 

[Harlock]

Okay, thanks again!