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Sony 7600gr and external loop antenna

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#1
Hello everyone,

Looking for something portable, I purchased a 7600gr which I should be receiving next week. My question is regarding the use of external antenna's. Can I use the 7600gr with my 80 meter loop? My concern is that the sony outputs a dc voltage from the ext ant jack and hooking it to my loop - may present a short to the ant jack; I'm no electrical engineer but I imagine the radio won't like that, LOL.

Thanks in advance for any advice.

73's de kb8viv.
 

ka3jjz

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#2
Well there are 2 issues here

The dc from the external antenna jack is meant to power an active loop such as the Sony AN-LP1 (I'm told you can find these on FleaBay sometimes). The easy fix for this would be to put an electrolytic cap in line - say .1uf at 10-25vDC (larger voltages wouldn't hurt anything).

Next is the 80 meter loop.

Warning - sarcasm mode on

Really?

sarcasm mode off :.>>

No portable is going to be able to handle the amount of RF that antenna is going to present. Not even close. Overloading is a very real possibility here. And I doubt the attenuator (the control is on the side of the radio) would present enough attenuation to handle this.

Fortunately there is a fix - a simple little box you can throw together in less than a hour if you have the parts in your junk box...

http://forums.radioreference.com/receive-antennas-below-30mhz/295299-great-first-timer-project.html

Now I know you would have to increase the pot's value - probably to 15-25k to get sufficient attenuation. The big plus here is that you can put the electrolytic right across the output jack, and not have to modify your feedline one bit. Apart from the static protection, this little box is nice and portable, and with a little ingenuity, could handle a lot of different feedlines.

Mike
 
Joined
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Messages
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Location
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#3
Hi Mike,

Thanks for the reply. I'm starting to realize that the 7600 is going to be my portable rig and I probably won't be trying to hook it up to my loop, LOL. I may pick up one of the an-lp1's to go with it, though. Thanks for the info.

Steve
 
Joined
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Messages
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#4
You could always place the 7600's whip antenna near the feedline from the 80 meter loop and add to the whip antenna's reception that way, using "field effect" reception. Just don't touch the whip to the feedline (especially if the feedline is non-insulated, i.e. it isn't plastic insulated coax).

Many feedlines give off enough RF to be picked up inductively by portable radio whip antennas. I was able to DX the Shortwaves with a Sangean 800A that way, placing the whip near the feedline from a 100 foot wire.
 

ka3jjz

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#5
Good thought, but it would depend on how the loop is fed into his shack. Ladder line might possibly work, but if he's using a coax feed from a current balun, I doubt there's much RF there to capture - at least, I hope not...Mike
 
Joined
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Messages
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Location
Kingman, AZ
#6
Well there are 2 issues here

The dc from the external antenna jack is meant to power an active loop such as the Sony AN-LP1 (I'm told you can find these on FleaBay sometimes). The easy fix for this would be to put an electrolytic cap in line - say .1uf at 10-25vDC (larger voltages wouldn't hurt anything).

Next is the 80 meter loop.

Warning - sarcasm mode on

Really?

sarcasm mode off :.>>

No portable is going to be able to handle the amount of RF that antenna is going to present. Not even close. Overloading is a very real possibility here. And I doubt the attenuator (the control is on the side of the radio) would present enough attenuation to handle this.

Fortunately there is a fix - a simple little box you can throw together in less than a hour if you have the parts in your junk box...

http://forums.radioreference.com/receive-antennas-below-30mhz/295299-great-first-timer-project.html

Now I know you would have to increase the pot's value - probably to 15-25k to get sufficient attenuation. The big plus here is that you can put the electrolytic right across the output jack, and not have to modify your feedline one bit. Apart from the static protection, this little box is nice and portable, and with a little ingenuity, could handle a lot of different feedlines.

Mike
The DC voltage on the 7600GR antenna jack DOES NOT power the AN-LP1 it only turns the preselector box on and off with the radio and you can find them new easily on Amazon and quite a few other stores. Surprised how much talking out the *** get's passed around about that since it's just a simple google search away.

Also many portables have been hooked up to more wire than that before so YES some but not all portables can handle it and people have done it before, it'll struggle a bit and I wouldn't recommend it but if you're crazy enough you can as I have used even a cheap PL600 on a full wave 80M loop plenty of times with nice results.

Dipoles are something to be careful of with the 2 wires so close together but lot's of people will connect just any old regular longwire or vertical and I haven't seen one short out yet.
 

ka3jjz

Wiki Admin Emeritus
Joined
Jul 22, 2002
Messages
21,679
Location
Bowie, Md.
#7
This page has a lot of what appears to be a good deal of information on this radio...

The Sony 7600 series page: ICF-SW7600GR, ICF-SW7600G

and it mentions that the ext antenna jack is indeed hot, and doesn't have enough juice to power a loop (many older Sony portables do this, however, so it's worth checking it). But it does suggest that a cap in line might be helpful (tho not really necessary)

Another point here that needs some clarity - evidently the 7600 has some diodes in the front end to prevent damage from too strong a signal or the antenna coming in contact with an AC source. You might want to consider adding the box I recommended anyway; I suspect getting this radio repaired at Sony might be iffy at best (and expensive), while if the diodes (or whatever you use in its place) in the box you use blow, it's a quick fix without losing the use of the radio (and being out money for shipping and repair at Sony)

Mike
 
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