Grundig Satellit 750 desktop portable

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nanZor

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The Grundig Satellit 750 is an AM / FM / SW / Airband desktop portable capable of ssb/cw as well. It retails for around $300 U.S.

This is my second purchase of the radio. The first one I had was so sub-par in performance that it met it's end at the recycler's about a year ago. A year passes, and I miss the little thing so much that I cross my fingers and try another one. Got a good one this time!

This radio is pretty well reviewed elsewhere, so I won't rehash everything about it, just the things I like. Again, unit-to-unit variances mean your mileage may vary.

This new unit is like an entirely new radio where everything works within reason.

No power supply hash or noise when using external DC! Amazing! I was expecting the worst. Still, I run it portable from batteries - but instead of 4 D-cells, I'm using rechargeable AA's inside D-spacers since it seems to draw so little current during use. Sure, I could use my Icom R75, but it draws about 10 times the power. I do small-scale solar as another hobby, so the small current draw for the Grundig was another reason for the re-purchase.

With headphones attached, I notice only a very tiny amount of antenna-effect when dx'ing FM, so my cure is to wrap about 4 turns of the headphone cord (actually a small extension cable) around a Radio Shack 273-105 snap-on ferrite. Most people won't notice, but I'm looking for it now. The headphone jack still feels like I'm breaking it when attaching a plug. Noticed that FM mode allows for the 10/20 db attenuator, but not the rf-gain pot. No biggie. And on FM you can change the bandwidth - but 99.9% of the time I use the larger normal bandwidth for FM.

HF/SW operations are just fine for what this is. SSB ops still done the same typical way: BFO at 12 oclock for USB, and 1 oclock for LSB. Allows one to tune through the bands in 1 khz increments and be very close to the correct freq all the time. Small bfo adjustments ok, but if you go past 11 or 2 oclock with the bfo, it is probably best to reset the bfo and retune the dial. Personal way of operating obviously.

Same flexible attenuator setup for strong-signal handling. 10/20 db fixed and rotatable pot. I'm no stranger to operating with the RF gain control, but my old one was so bad that even this was too much to bear. Either Grundig improved the line, or my old one was just faulty to begin with - hard to tell.

Weighted tuning knob is actually tight! My old one was clearly very loose, and required me to pull it off, remove the felt cover, and torque the nut on the encoder shaft a bit. Oh happy day! Still, I avoid putting vertical pressure on the knob by not using the finger dimple and tune via the knurled threads and the fast tuning option / keypad when necessary. As before, because of the weight of it, when transporting it by vehicle, I store it face up - or remove the knob altogether.

MW rotatable bar antenna works! My old one was tweaked. Prior to recycling, I broke it open only to find that they used a pretty normal ferrite inside, and only using about half the length of the housing. I wish they would put a monster ferrite inside, but then again, Grundig sells an accessory tuned-loop for more hard-core BCB dxing. I don't think I'll be taking a hot x-acto knife to mine to mod it for a bigger ferrite as it works ok as is.

S-meter is the same old eye-candy. Kind of wish they had an external jack to make it easy to hook up something even bigger.

Memory storage / pages / banks is very cool. However, unless there is some magic I'm missing, I cannot get it to scan the memory channels. Ok, the usefullness of this is questionable as it is a timed-scan and not rf based - changing channels every 5 seconds. Load up a page with 12 frequencies, and have it take a minute to get back around to your first memory? Heh, not useful, BUT for monitoring maybe only two or three HF channels on a dedicated page, it might be ok - at least for me. Not a showstopper, but if anyone knows how to do it, let me know.

Speaking of not being a scanner, this unit works GREAT on Airband! My older one had a major loss of sensitivity above 128 mhz, so I was unhappy as that meant that about half the airband was usefull to me. This unit however, works very well on the entire Airband. I use dedicated scanners for Airband, but this is a real treat to do it the old-fashioned way if you don't mind sitting one one frequency. To hear the full fidelity of airband transmissions (good OR bad!) helps put you in the cockpit. I typically run the squelch just barely above the noise, even though there is a gentle background wash heard if I get close. Then BAM! Room-filling fidelity of the pilot and even background alarms/alerts/prop noise in the cabin. You don't get that from a scanner. Before the 750, I used only scanners on airband, so this type of operation seemed a bit cheezy at first. Then you warm up to it. Then you realize the difference between radios and scanners. Your Dad or Grand-Dad would approve wholeheartedly. :)

WARNING! If you do adjust the squelch, especially if you run it just a little bit beyond the noise, but not fully squashed, and return to HF operations, do not forget about it! It will seem like you have attenuation on when you don't obviously, and since the squelch is not the on/off type, but the older audio based (like old cb's) units, you might be scratching your head when HF signals are a bit distorted while trying to rise above the squelch setting. Harder to explain than perform. :)

One nice thing is that if you choose slow tuning for Airband, you can tune off frequency to compensate for tower drift, or moving a little bit away from a noise source by 1 or 2 khz. I'm not sure if the radio is actually able to fully tune the rf-deck between the typical 25khz segment channel spacing (even though the display says it does in slow mode), so that would be something to test for those who live in areas that use 8.33 khz spacing. There doesn't appear to be any System Code Setting for 8.33 khz.

There is no bandwidth choice when using airband - wish there was! It would make more sense to allow for a narrower bandwidth choice here when dxing weak airband sigs, than on FM for example.

And, the FM external antenna jack works for Airband as well - makes sense since it is just above the FM band. But, check this out - I put an airband-specific Maldol AL-500H whip on a right-angle bnc adapter into the FM antenna jack, and it worked ok (internal collapsed). However, the built-in whip, when extended only 4 or 5 segments, actually worked better. Adjusting the built-in whip to only 4 or 5 segments even worked better than when fully extended. Tune in a local ATIS station and you'll see. Makes me wonder how much isolation there really is between the internal/external switch.

I didn't do much with Long-Wave - although I guess I should be chasing some of the last remaining CW NDB airband beacons there! Need a real antenna for that though.

HF antennas while portable - so many ways to go I won't even touch that here, except to say that a modest improvement can be had by doing nothing more than attaching about 3 - 4 feet of wire to the ground (black) side of the 500 ohm jack and letting it hang or lay out flat when using nothing but the internal whip. The guts of the box don't make a great RF ground. :) Stick it in the spare compartment when lunch is over.

Don't break the vertical whip! Yes, there is a hinge at the bottom of it, but it is a tight pull straight up to get the hinge out in the open. Don't manhandle it out - firm but gentle is key, and pull on the fatter sections!! Note that the top is a plastic cap, so don't clip extensions to the plastic cap. Man, those last two segments are really thin so be careful there too if you clip anything on it. I'd say use the external jack even if you are more or less duplicating the small whip and placing it near a curtain or something - that whip wants to bend at the end if you put stress on it. The beefier whip from the S350/S450 series should have been used here, so just be careful.

I'm extremely happy with this NEW unit. Reasonable performance all around this time.
 

lanbergld

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The tuning knob on my S-750 has an ultra smooth gliding quality to it. That along with its generous weight, it feels better than the VFO knobs on certain expensive communications receivers I've had.

I'd like to mention the spectacular LW Dx'ing I'm getting with this. I simply do an inductive coupling with a large tunable ferrite looptick placed next to the radio. Been getting European longwave broadcasters with remarkable fidelity. Regarding air band reception you're absolutely correct that the attached whip works better than an antenna conencted to the external jack.

I'm really glad I bought the S-750. I had no idea it'd be this good of a radio. People who give this unit harsh reviews really ought to learn how to enjoy their radios, instead of obsessing about small things they consider imperfect or odd.


Larry
 
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nanZor

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That's great to hear about the LW reception. I haven't tried it with this receiver, but it is tempting to try and run a very very long wire, or some sort of monster LW loop.

Yep, there's not much point in using any stubbie or handheld whip for airband. Of course, attached to an outdoor groundplane it could be a different story. :) Since there doesn't appear to be separate bandpass filters for fm and airband, the front end is wide open from 88-138 mhz. Some might run into FM overload / desense when listening to airband. (or even visca versca!). An airband-only filter, or perhaps an FM trap might help. Although not ideal, even a quarter-wave stub for FM might do the trick. Threads for this elsewhere here if you run into this problem.

I have to agree that I enjoy my 2nd version. I just wish there was more competition from other manufacturers in this segment - alas, they left in the 80s/90's...
 

Turbo68

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Hi heritzan had mine 750 for a while only monitor hf aero excellent hooked up to my Wellbrook-ALA1530 active loop vhf airbands excellent hooked up to an Icom-AH7000 discone clarity of the speaker is good due to adjustments for base,treble..

Regards Lino.
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nanZor

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Nice setup! I dig small aperture loops myself - although the neighbors killed it by going BPL ethernet over powerline to drive their sat tv boxes. Luckily the amateur bands are trapped out 50khz on each side or so. But without a localized source to null, my loops are useless for swl / utility. :(

Glad you mentioned audio - it is good. But I found an issue with my set that might interest those who use headphones for HF comms and really like a quiet audio amp. Most people won't notice probably.

Without any audio drive, or very little of it, you can hear a very low level popcorn frying sound from the audio amp. (A TDA2822 I believe, 250mw out) Giving the AF pot a little gain usually rides above it so that you don't notice it as much. The jack on the 750 allows use of either mono or stereo plugs to be used.

Yet depending on the headset, it can be obtrusive at even lower drive levels, making itself heard and possibly contributing to listener-fatigue for those long sessions.

I have tested out various inexpensive headsets, and found these results:

With stereo headsets, the low-level popcorn distortion is different in each ear. A quick cure is to use a mono adapter to mono it out so that your brain can tune it out more easily.

Typical hi-fi earbuds needed more drive, and the popcorn was the most obtrusive compared to other headsets. Cranking the AF gain to override it worked, but now I'm at a volume level I didn't desire.

Inexpensive comm-quality headsets were the right choice - I tested 3 different sets:

Kenwood HS5 / HS6. Both of these are wired for mono, rated at 8 ohms impedance and produced quality sound, while really dropping any low-level popcorn way down. I didn't need to drive the AF pot so much to override it like the hi-fi earbuds.

Yaesu YH77sta - these headsets are wired for stereo, rated at 35 ohms, and like the Kenwoods, provided quality sound. They seemed even more efficient - whether this is due to the speaker elements, or the slight mismatch in impedance, I don't know. They needed about 1/8 to 1/4 less drive on the AF pot compared to the Kenwoods for an equivalent volume level. They actually could be driven into distortion at the extreme ends of the AF pot range - impedance mismatch here? Not sure.

Obviously it is not surprising that comm-quality headsets perform better than stereo earbuds. Right now I prefer the Yaesu headsets, but from the testing, I now use a mono adapter since the Yaesu's are wired for stereo, even though electrically it wasn't necessary. Any low level weird stuff that might show up in only one ear or the other gets tuned out by my brain more easily with the mono adapter.

For most, this isn't a really big issue.
 
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nanZor

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Line Level Audio is great!

Just checked the line level audio output and it is nice and clean with a flat response!

Looked around for an audio amp to feed it into and all I had was a Grundig S450DLX. :)

Now we're talking - good response, no hum or noise, and plenty of oomph in the audio. This also bodes well for the 450dlx audio chain, which I believe has the better audio amp. (both rigs running solely on batteries...)

Interestingly, the 750 allows for tonal control of the line-level output with treble only. The 450dlx serves only as an amp, and there is no tonal control on it.

Man, ALL radios should have line-level outputs!

At any rate, the 750 works well on it's own, but if you are going to use outboard audio filtering, such as a cw filter perhaps, tie into the line level outputs..
 

nanZor

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As a clue to the build date on my newest one, the AC adapter has:

"Made in China 10 AUG"

So I take it to mean Aug 2010. At least for the supply, but hopefully the radio was produced near that date.

Get this: I also picked up an older S350DL ("drifty 350") on clearance with full intentions of cannibalizing it. I'm going to mod the 750 with the sturdier whip from the 350, and possibly use the ferrite bar from the 350 and pop that into the 750 as well. I'll let you know if/when that happens.

Thing is, the "clearance" s350dl also has an ac adapter date of Aug 2010, so that appears to be a late model as well. I don't know if I have the heart to rip it apart now, although the single conversion and sloppy tuning don't hold a candle to the superior 450. :)
 
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nanZor

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CW/SSB distortion fix:

I performed a mod found on a Yahoo group for the 750 and it solved a problem I was facing with premature distortion.

Much of the distortion was cured by the old tried and true technique of just cranking the audio and riding the rf-gain.

The problem with that was that by the time you cranked the rf-gain down (and used attenuators) enough to solve the distortion, the overall gain was practically zilch, especially if you use even a modest external antenna.

To get to the point - the RF input is not actually being overdriven, it is the AM IF output level that is too hot for my 750. A simple resistor and cap to ground from pin 18 of the RX ic chip (basically a 47uf cap in series with a 2.2k resistor or thereabouts) brought that AM IF level down to a reasonable level. Of course it works on AM, but is also the IF source for CW/SSB as well.

What a surprise to find that the actual RF amplifier can actually hold up reasonably well for a portable!

If you run solely from the whip, you probably won't run into this issue. But the 750 begs you to use external antennas with it's nice selection of external antenna jacks. If you have this issue, see the Yahoo group with pics for more info.
 
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nanZor

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Update: I've finally settled on a 2.7K resistance in series with the dc-blocking electrolytic cap to settle the overboard premature distortion issue. It appears that this issue is not Grundig specific -- this mod has also been performed on the sister radio, the Tecsun S2000 with the same good results.
 

nanZor

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Fixing the rotatable AM ferrite antenna

The loud pops that make you jump out of your chair when rotating the AM antenna has a simple fix. At least temporarily. Seems like the mechanical/coaxial ring setup inside is oxidized. I haven't taken it apart to verify that.

Turn the radio OFF!

Push down firmly on the CENTER of the antenna between your thumb and forefingers. Rotate this around 360 degrees or more while applying firm pressure. Just try not to put any side leverage on the bar, or manhandle it so bad you break the case.

It took about 20 or so turns of firm pressure to perhaps wipe the internal contacts clean. I also did the reverse by pulling up from the CENTER firmly and twisting it around just in case.

Merely exercising the antenna by twisting it without any pressure didn't seem to do much, so yeah, I got a little bit angry and discovered that it needed a bit more motivation. :)

MUCH better - no pops or crackles when rotating the antenna. How long this will last, I don't know.
 

nanZor

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Internal whip on FM / Airband

While it is no surprise that an external outdoor antenna for FM/Airband is better than the built-in whip, I was surprised to find that even a 3rd-party telescopic whip has a very noticeable improvement in sensitivity on FM/Airband, no matter how much I tried to fine-tune the built-in one.

I discovered this quite by accident as previous tests with ducks and specialty whips like the Maldol AL-500H were actually on par or less effective than the built-in whip.

The trick seemed to be to just use a PLAIN telescopic (no loading coils or other enhancements). In my case, I used a simple Diamond RH-789 telescopic, which has a knuckle at the base which makes it easy to bend 90 degrees upright, and still clear the case. For FM fully extend it. For Airband, collapse the furthermost element back down inside the one preceding it. Anyone trying this with the venerable RS coil-loaded whip should short the low-band coil by pushing the element just above the coil back down inside.

I always thought it was just a simple matter of adjusting the length of the built-in whip, but the results from a 3rd-party telescopic were quite more noticeable than just a simple length adjustment. Former ATIS and AWOS signals that were just near the noise level, cleaned up nicely - although we're not talking about bending the s-meter needle.

I don't know if the loss of the built-in whip is due to impedance matching, bandpass filtering or what, but from now on, I'm using the Diamond RH789 attached to the external antenna jack for simple portable ops for FM/Airband use. (and yes, I didn't forget to switch between internal and external.) :)
 
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NeedtoKnow2

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Thank you for your review. It is certainly better than several I have read (see comments below.)

My radio ownership points of reference are a 30-old GE 10 band Model 72971A , and a 15 year old Radio Shack DX390.

What are your thoughts about whether or not this 750 will be a significant enough improvement over the above radios for me to justify the $259 price tag? I am seeking improved SW performance over what I have, I like the ergonomics (knobs vs. multi-function buttons) and I appreciate the methods of antenna connection – I will be using a ENDFEDZ EF-SWL.

I have never seen such widely varying reviews on a piece of electronic equipment as for this radio. But reviews have definitely improved over the past year or so. It sounds like they have done more to the radio than just adding metal knobs.

Here are two examples of mediocre reviews:
Grundig eton Satellit 750 - Tecsun S-2000 Review - N9EWO -
Grundig Satellit 750/Tecsun S-2000 Review Posted « radiojayallen

These are not terrible, just not very inspiring. The n9ewo review doesn't reveal a review date. Even his annotated comments could have been from more than a couple of years ago. I sent him an email asking his to clarify review dates.

Amazon reviews have definitely improved over the past year or so.

I don’t want to spend significantly more than the $250 range on a receiver, so the ICOM class units are not being considered. Are there better performing radios in the price range I am considering that I should look at?
 

NeedtoKnow2

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What are the improvements?

Based on reviews of this model over the years, it appears that Grundig has done more than merely change the plastic knobs to metal.

By numerous accounts, it seems that other aspects of this radio have been improved as well unless noted "improvements" are random variations in quality control.

Also, some of the more positive reviews are the result of users having the patience to learn how to tune or tweak the radio as a radio and not just as an appliance.

Is there any solid indication that noted improvements are the result of subtle circuit tweaks as opposed to variable quality control?

I would like to see a list of the improvements that users believe are a result of design or manufacturing changes.
 
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NeedtoKnow2

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Wd-40

The loud pops that make you jump out of your chair when rotating the AM antenna has a simple fix. At least temporarily. Seems like the mechanical/coaxial ring setup inside is oxidized. I haven't taken it apart to verify that.

Turn the radio OFF!

Push down firmly on the CENTER of the antenna between your thumb and forefingers. Rotate this around 360 degrees or more while applying firm pressure. Just try not to put any side leverage on the bar, or manhandle it so bad you break the case.

It took about 20 or so turns of firm pressure to perhaps wipe the internal contacts clean. I also did the reverse by pulling up from the CENTER firmly and twisting it around just in case.

Merely exercising the antenna by twisting it without any pressure didn't seem to do much, so yeah, I got a little bit angry and discovered that it needed a bit more motivation. :)

MUCH better - no pops or crackles when rotating the antenna. How long this will last, I don't know.

I heard one user was advised by Grundig tech support to use WD 40 with a lot fewer turns of the antenna, with good results. I'm not sure exactly where it would be sprayed - any ideas? Do you have to open up the case to accomplish this?

Some folks discussed installing a larger ferrite bar than the one inside the unit. What kind of "external" antenna would have a similar or better result than installing a larger internal ferrite bar? I plan on hooking up an ENDFEDZ EF-SWL for shortwave listening. Will that improve AM beyond the internal bar?
 
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ka3jjz

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While any wire antenna would improve MW reception, it's at a price - everything comes in from all directions with no way to null one station over another. That's why loops are a very popular tool when DXing MW stuff.

As I recall, the PAR really isn't designed to go down that low - if it were me, I'd look at getting (or building) a box loop or similar if I were into MW DXing. I'm quite sure the NRC or the IDXC websites have plans for such, and it shouldn't be hard to find plans with a well structured Google search. In addition we have a few linked in our Loops wiki below...

Loops - The RadioReference Wiki

HTH...Mike
 

NeedtoKnow2

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While any wire antenna would improve MW reception, it's at a price - everything comes in from all directions with no way to null one station over another. That's why loops are a very popular tool when DXing MW stuff.

Loops - The RadioReference Wiki

HTH...Mike

Are there any preferences between the Grundig loop (about $30) and the Terk loop (around $40) for use on the Grundig 750??
 

ka3jjz

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If you read the description of the forum, you'd find that the forum is for MW antennas as well . MW is the more technically correct term for what the lay folks call the 'AM band'.

Hopefully someone has tried these antennas with the 750 - if not, both are quite inexpensive and certainly worth alook...Mike
 

NeedtoKnow2

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If you read the description of the forum, you'd find that the forum is for MW antennas as well . MW is the more technically correct term for what the lay folks call the 'AM band'.

Hopefully someone has tried these antennas with the 750 - if not, both are quite inexpensive and certainly worth alook...Mike

Ahaa! Reading forum descriptions can be a really good thing. Old perceptions of things, like AM and SW being different animals, are hard to break.
 
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