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Reviews Categories | Antennas: HF Portable (not mobile) | Degen DE31 (Kaito KA31) Help


Reviews Summary for Degen DE31 (Kaito KA31)
Reviews: 5 Average rating: 4.6/5 MSRP: $30-50
Description: Active Magnetic Loop for indoor use
Product is in production.
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You can write your own review of the Degen DE31 (Kaito KA31).

NASSAU Rating: 5/5 Jul 28, 2013 08:27 Send this review to a friend
Cheap and effective  Time owned: 0 to 3 months
Sold under several names, mine is the DEGEN 31MS Active Loop Antenna. I paid 18 from Amazon.co.uk, wanting to try an active loop antenna - even a basic one, just to see what sort of effect it had on general SWLing.

Overall, it is good for parts of the HF band, with less efficacy on the higher frequencies. Essentially, while I listen from 7000 to 15000KHz there is typically a sweet-spot on the tuning capacitor that gives a noticeable gain in signal. I cannot quantify it alas as I have no suitable meters, eg no S-meter, on my Sony SW7600GR portable receiver. But dailling the capacitor backwards and forwards creates a noted step of signal/noise where the gain for that frequency is located.

This cheap and portable, collapsible antenna at least matches the whip/5m roll-up wire atenna of my Sony 7600GR. In several instances (9610Khz Radio Australia (100Kw tx to SEAsia) or 6130 KHz Radio Lao (50Kw tx to SEAsia), both received on a recent business trip in Beirut, Lebanon) where instrumental to be heard with the Degen active loop: the whip and wire did not pull in the signal enough.

I'm very pleased with this effective, yet very affordable, antenna for travelling. Recommended for essential SWLing on portables.
 
OLLIEOXEN27 Rating: 5/5 Sep 12, 2011 15:09 Send this review to a friend
fine sw mw solution  Time owned: 0 to 3 months
I purchased the TG34 SW MW version of this antenna from Hong Kong for $23 including shipping. It works fine and is useful to peak signals equal to a random length outside antenna. On medium wave it did not appear to work because I was unable to peak the background noise however when I tuned it to a medium strength daytime station voila - it improved. Probably the best $23 I've spent in ham radio. How long it will last? Probably awhile if treated gingerly.
 
JETPILOT Rating: 4/5 Apr 30, 2008 10:14 Send this review to a friend
Kaito/ Degen KA31/KA33/TG33/TG34 Fun antenna, works @ discount  Time owned: 3 to 6 months
This is a fun little portable "active" amplified loop antenna. I purchased it at the same time as my DE1103 radio (which I'm impressed with) on eBay. It took +3 wks but worth it.

This antenna is sold under different names, Kaito (import) or Degen/generic (china version). The KA31, I believe now KA33, Kaito's latest version of this antenna. The ant tested was on the TG34 model (replacing the TG33 model). It does not say Degen but its their brand and I am sure the same as Kaito.

You get a lot of stuff with it. You get clip & suction cup to hang-up a "diamond" loop with a telescoping antenna, used as a "spreader". I have no idea the affect of this metal rod in the middle of the loop, but more on how it works below. At the feed line is a switch for SW or MW. That switch does do something and improved nose level when switched while on AM MW BC band. It comes with a long feed line (15'). The amplifier is the size of a large pack of gum. It takes two AAA's (not incl). It has an on/off switch, led on light and a small thumb tune dial, unmarked/no scale. I found dialing down biused more towards higher freqs. I opened the the amp up with three tiny screws and found the on/off switch, resistor, potentiometer/variable capacitor(?) and an IF Transformer. I did not look under the board, it was in there for good, so I did not push my luck. From the amp is a short pigtail with a 1/8" stereo plug. You get two attachments, a loop-stick booster and one two lead pigtail with alligator clips. The DE1103 has a 1/8" antenna jack and the loop plugs in direct for SW and FM. For AM MW BC you use the loop booster, which is fun to play with. If you have no leads or have dedicated antenna input, the third way to use is the pigtail and clip attachment, connecting to the external antenna or to the radios wires leads. I tried all three methods on 5 radios, 2 SW general band and 3 AM or AM/FM radios.

Radios I tried it on where the DE1103, RX320D for MW and SW. For MW AM BroadCast I tried three cheap AM or AM/FM radios, including: Panasonic portable black/white TV w/ an am/fm radio (analog), Sony (ICF-34) AM/FM/TV/WX portable with ac/bat power and a handheld AM/FM stereo digital tune "optimus" (aka radio shack, cat # 12-792), with a small 2" or 2.5" loop-stick towards to bottom (it's a small radio not much room for a loop-stick).

First about loops and amplified or active antennas. For you experts you probably know this, but from my novice experience and reading there is a plus/minus or Pro/com with any tunable active loop. It is said that you boost signal and noise equally. Well I found that true sometimes but not always. Bottom line it make un-listenable radio listenable. Some times it was still noisy and others it cut noise. The tuning is a pain of you are scanning, but if you are going to stay put on a station or a few favorite stations the tuning part is a minor issue. When you do tune it (with the little thumb dial on the amp) and the station comes in loud and clear its worth the effort.

The fact is loops are directional and tunable. That is good and bad. On a scale of 0-5 it can make 0 stations be a listenable 2-3's. It can make a 2-3 stations more enjoyable. I found on strong stations it even cut noise sometimes but did nothing for the signal (which did not need it). Sometimes it made the signal louder and more disginishable but also raised the noise equally. I did not play enough with moiving the antenna around. Also I am doing this around a bunch of computer stuff and AC stuff. Out in the open who knows.

The second good/bad is a fact of life, is that its tunable, a feature which brings in weak stations. The down side is you have to tune it each time you change radio stations. The tiny dial on the side of the amp is super sensitive. It's very small volume like control, but it is clear when you move this, it's an active loop, it does do something. If your active loop is connected and you have it badly mis-tuned, it can have the total opposite affect of bringing in stations, it can reject or block them, so you tune with it off or disconnected and than connect it and tune it. If you are listening to one station than this is not an issue.


**First using the Loop stick boost on AM MW BC band.

One note, you have to know where the loop stick is inside the radio. I either have had them apart or hunted for it using the loop stick booster. Also moving the booster around, switching the booster leads around 180degs can have big affects on signle. The down side is you can't hold it there forever, so some non-stick frig tape is a must for long term use. Some times it can just sit on top (about where may loop sticks are mostly) but other times you need to hold it to the back.

One real WOW moment was when I just dialed to static and put the loop-stick booster to the radio about where I knew the internal loop stick was. Leaving the radio alone I tuned the antenna and brought in a signal I could not hear other wise with the radio's antenna alone! Even moving the radio around with out the Active loop connected did not bring in that station. I repeated many tries on all radios and had improvement on all of them, in a similar fashion, but this one radio and station gave spicatcular results.

The directional part of the loop is a question; a few times I moved it and there was no change, but one tell-tale indication was tuning in a weak station, with the Optimus handheld am/fm radio. Moving the loop made a difference as described in the below par.

The second WOW moment using the loop-stick booster was when I tuned in a weak station, than put the booster up to the radio; tuning brought in a totally new station coming in stronger! The down side was this new station had heterodyne (squeal), no doubt from the other station that was now blocked. Moving the loop around (stuck to the window) made the heterodyne disappear. Moving the antenna had no affect on the signal strength (by my ear) but the squeal was gone. It was hanging vertically. It took only a small movement of the bottom to the side to do the trick. So instead of vertical it was angled slightly. Small change made a big difference. However with other tries moving it the loop had little or no affect.

The base of the loop where the feed line is a switch with SW/MW. It did make a small difference in noise.

Trying it on all radios there was no doubt improvement on a scale of 0-5 at least 2 some times more. Results varied but the signal amplification sometimes reduced noise and other times it amplified the signal and nose equally.

SHORT WAVE: I tried this on the Degen DE1103 and Ten Tec RX320D. It worked similarly to AM radio, but of course the method of connection was different. The Degen has an antenna jack. The RX320D has a RCA jack. I jury rigged a RCA jack and used the TG34 alligator clips to make the connection; not high tech but it seemed to work as good as the built in preamplified telescope provided with the RX320D. When you plug in an RCA jack it disables the telescope antenna.

Bottom Line: I am a novice and getting into DX'ing after a long absence, so warning I am easily amused or impressed, but fact, it does work. I am not naive enough to think it's better than a good outdoor antenna, it is not I am sure. However for something that can fold up (size of a pak of cigs), you can hang it up in your hotel room or on the road; it isn't bad. It's really ideally suited to bring in that one particular station you want to listen to, that's a tad too far to enjoy. It's OK for scanning but more work for sure due to tuning. This antenna can make a difference. I tried it with cheap radios and expensive radios, it worked to a degree on all. Some results were fair and a few where spectacular. Some stations where not heard with out the loop became listenable. No matter how I orientated the radio with out the active loop I could not get the station; connecting the loop brought it in. Nuff said, the active loop DOES WORK. On a scale of work I give 5 with all the limitations above. I am comparing it to the stock internal loop sticks, built in telescope antennas and other indoor antennas, with PRICE factored in. It is a bit of a Rube Goldberg deal, you have mount the loop (on clip or suction cup), feedline, amp and adapter. There are lots of parts.

To a real antenna or a real BIG loop it might disappoint the Pros out there. The only critical comment on quality is the wiring seems a tad delicate. You have to push/pull the plugs (which connect and disconnect good force) at the plug, not the wire or you'll break the wires, which are small gauge.

If you can get one at a discount, I paid $22, free shipping as a package deal, it is recommended. $39? Well than it would not be as good. If you just want it for an AM radio may be the Terk passive AM loop might be better (which I have not tried personally). The TG34 uses batteries, so keep that in mind; don't forget to turn it off. I have a bunch NiMH rechargeable so its no big deal if I forget. Have not used it enough to get a feel for battery life.
 
KC2OYZ Rating: 5/5 Apr 5, 2008 18:51 Send this review to a friend
Want to enjoy SWL on the cheap? Get this antenna!  Time owned: 0 to 3 months
I live in an a Brooklyn apartment with condo police - lots of RFI, all kinds noise, and serious antenna restrictions. I have pretty much given up getting on the air from my home QTH but I still enjoy SWL. But a long wire makes the neighbors nervous and pulls more noise than signal into my R75.

Was considering AOR's LA-380, but $370 is an awful lot to plunk down for an indoor antenna. Sony loops and the Degen DE31 are always on eBay - I figured for the price the Degen was worth a shot. It was about $30 with shipping from Hong Kong - came, brand new, in less than a week.

I am very happy with how good it works, even though it looks like a piece of junk! It hangs in the window, takes up very little space, reduces the noice floor significantly,the tuning unit is very selective and the amp gives gives good signal gain.

I did a head to head - Degen vs a long wire dropped out of the window using the Palstar active antenna, snagging international broadcasts on 41 and 49m in the evening. It was no contest - the Palstar is going on eBay - the Degen isn't going anywhere! (As another reviewer mentioned, it does better with a low impedence input)

If you've got a situation like mine and want to enjoy SWL on the cheap, get this antenna.

Mikey
KC2OYZ
 
KD7RDZI2 Rating: 4/5 Mar 29, 2006 20:20 Send this review to a friend
SWL antenna (from 80 to 15 meter bands)  Time owned: more than 12 months
I bought the active magnetic indoor loop DE31 by Degen from ebay and paid about 25 USD should be similar to KA31 by Kaito.

The unit looks like a small loop (abt 30 inches wide I believe), at the bottom there is an amplifier, then about 5 meters of small coax, a tuning unit powering the amplifier and some small coax going to connect to the antenna input. It comes also with some clips to connect to a telescopic antenna.

I found the antenna very selective and it is very good for portable radios that suffer from overloading.

You can use such active sensitive antenna without using any preselector without too much risk of overloading the receiver!!! The tuning unit infact is very selective (it is very touchy) and acts similiary to a preselector!!!

This antenna is rather genial and does not cost a leg. I think it would be a good solution if you can put the antenna under the roof protected from water (it is not waterproof!!), in case you live in a attic. It's perfect for traveling and portable use (for instance you can put it on the top of a cheap 7 meters fishing rod easily).

I found that signal can be further increased putting a 50:450 ohm transformer T9-1 by Minicircuits between the DE31 antenna output to the antenna input of my Degen DE1103. The use of a matching transformer depends on the impedance of the antenna input and may increase the signal of some db.

I believe the antenna has a somewhat low impedance output and should deliver maximum signal to radios having a 50-75ohm antenna input without using any input impedance tranformer.

Overall it can be a great value for any portable!
 


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