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Reviews Categories | Antennas: VHF/UHF+ Omnidirectional: verticals, mobile, etc | Diamond D707 Help


Reviews Summary for Diamond D707
Diamond D707 Reviews: 2 Average rating: 4.5/5 MSRP: $180
Description: Receiving antenna with built-in preamp
Product is in production.
More info: http://www.diamond-ant.jp/ama2/eng_ama_2_6_1.asp
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HD650 Rating: 5/5 Jul 23, 2005 21:39 Send this review to a friend
Additional reporting  Time owned: 0 to 3 months
Tested it for nearly a whole day and confirmed that my D-707 set is pretty deaf for anything below 200MHz. Same receiver (FT-8800R), just swapped the antennas from the D-707 to anything from X-200 to telescopic whips (with and without coils). I am not sure if this is only perculiar to my D-707 or is it a performance design issue, so take note if you want to purchase. What i mean by deaf is no mistake, i mean there is no mistake between the performance of getting under S-5 signals with FT-8800 + D-707 vs S-10 signals on FT-60R + SRH519....(mainly tested on marine VHF so it would definitely not favour SRH-519)

Set it up so that the D-707 and X-200 are nearby just 0.3m apart. I presume they won't block each other in a noticeable sense. Location is about 30ft above ground.

For higher frequencies it's a blast. I could hear 250MHz wireless mikes around the neighbourhood which is impossible with all my other antennas but possible with the D-707.

435MHz range, nighttime came and there are some long constant transmissions which enabled me to test the D-707 vs X-200....and in this freq range the X-200 is definitely optimised. Performance is somewhat mixed. With 1 transmission X-200 = S4 and D-707 = full S-10, with another X-200 = S-3 while D-707 is S-5. For latter case, the receive with D-707 definitely sounds stronger with less noise.

446 and 462/467MHz : Again, could hear some lengthy ragchewing with US-based GMRS or FRS sets (you could tell from the wobling roger beeps). 446 sets are probably those low-priced sets gotten from my neighbouring country in which this freq service is perfectly legal. Though 446 and 462/467 might be a bit of a stretch for the X-200, the D-707 really pulls in the signal much stronger than the X-200, at least 3 S-units more. Received audio also sounds stronger and clearer, that's the most important. My FT-60R + SRH 519 placed beside the 2 antennas could copy a faint transmission but i could not make out anything even with the squelch open.

I just discovered that there is quite a lot of activity in the 800MHz range which I have not been able to hear that before. I suspect it's from my neighbour country, you see I live just 30m from the coast and I'm seperated by the expanse of a sea from my neighbour country by about 40km (25 miles?). There are at least 80 frequencies in use, and i suspect this is a trunked service use by the port as they are talking about loading and unloading of containers etc. They are definitely repeaters because a transmission would end (hear the squelch tail) but there is still signal for about 5 seconds before it'd close altogether. I don't think operations of this kind of repeater is the same as the regular repeaters in the States (ie antennas mounted at very high points like mountains and operate high power), i think it's probably very local. Anyway, i plugged in some other telescopic whips to the FT-8800R extending to various lengths and i was unable to copy anything. With the D-707 i was able to get about S-2.


Too bad you cannot transmit into it, else for very high VHF and UHF it really pulls in everything in a small package. A small package that could approximate the performance of a much longer base antenna. 5/5 for UHF performance.
 
HD650 Rating: 4/5 Jul 22, 2005 22:16 Send this review to a friend
Works only for above 300MHz  Time owned: 0 to 3 months
First, I have to declare I am not in the States so operating environment is different.

Just got this receiving antenna with preamp because of its handy size, it's small enough to put it by the window frame. I actually was looking for a D130 or D150 discone but they don't stock it. Besides my dealer friend is selling this at only about US$80 so i took the plunge.

My listening equipment is a FT-8800. I was initially quite shocked at its performance when listening to VHF from about 110-162 (Air to marine). No it's working alright, you can see the S-meter going up and down when you tune the gain controller + and -. The thing is that a S-10 full signal on a FT-60R and SRH519 (20cm long antenna) is only S-3 on the FT-8800! I though i could have gotten a faulty set or something is wrong with the FT-8800.

Nope, plugged in my Diamond X200 base antenna and FT-8800 shows S-2 with a distant airport ATIS weather broadcast while FT-60R/SRH519 is deaf. FT-8800 is working alright.

The next few days i started to tune to UHF. I could hear some wireless mikes at 250MHz ok, got similar performance on my FT-60R. Tuned up to 350MHz range and that is when things perk up. A station which i am familiar with on a SG-7900 and FT-8800 is S-5, on the FT-8800 with D707 it's S-7. So it works! What a relieve!

Some of the people in my town are using the US GMRS bubble pack sets (462 and 467MHz) and i could hear them about 1 units better on the D707 compared to the X200. On the SG-7900 it is probably about 2 S-units. So it works.

All the while i am using max gain. Forget about the +20dB paper spec figure.

I'd be further testing it with other stuff like my scanner (low-end Uniden 92XLT) and see the VHF Low, VHF High and UHF characteristics. Summary is that for VHF high (air and marine bands) it's very deaf. It's good if you don't have space, a 1m tall active antenna can approximate the performance of a 2.5m X-200 antenna for UHF, not bad.

Will report additional findings, if any.
 


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