When it comes to HT antennas, there are plenty of fish in the sea. For portable outdoor, I mostly stick with my Nagoya NA-701 Whip antenna. Its cheap, it performs well enough to work the repeaters I usually have to work and it performs well better to monitor Freenet/PMR466 frequencies while for example out geocaching. But where to put the HT and the antenna? I have never seen a reasonably used HT rubber whip that was not bent quite much to some direction because of keeping the HT in the jacket. This will in most cases not hurt the antenna itself, but since most HTs use rather sensitive SMA connectors, the mechanical influence, the bent antenna tells us about, ends up in the HTs antenna jack and may sooner or later lead to damage. The most common HTs all have the jack screwed tightly to the case or shielding, so damage might not be the first to happen, but well... this all leads to me not being comfortable, carrying my HT with that whip in the pocket.
Long story short, I was looking for an antenna that was short and working in the cases I needed it to work:
When the package arrived, I was very surprised by the actual size of the Antenna:
Diamond SRH805S - Some figures:
Length/diameter: 44mm / 13mm
Compared to my HT, the Antenna is just tiny and looking at that, I could not imagine, how the not so well known SRH1 (2.5cm length, 2m single band tx) would look like. The also quite small TH-F7 Transceiver was looking even more portable, with that antenna on it. I really liked the look and feel of the antenna.
The antenna was shipped with a rubber spacer for HTs with quite long SMA connectors, so that the antenna body would rest on the HTs case and dampen the pressure on the delicate connector. I didn't need to use that on the TH-F7, on the Wouxun KG-UV2D with the SMA gender changer screwed in instead, it proved really useful.
I was wondering, how they would build a 1/4 wave resonant antenna and found a nice picture on google images, explaining the matter... I am not very comfortable with posting it here, but I didn't find the original source online. It shows the original construction of the antenna:
The picture explained the springy noise, the antenna produces, it you bump it. I was wondering, if an antenna of that size could perform on 2m at all. Thinking about the SRH1 - well, its 2.5cm for 2m - I thought I could give it a try later.
Hence possessing a Wouxun KG-UV2D as a second hand and secondary unit, I was looking for a similar antenna for that device. The unit bears the burden of a male SMA "sink" on the HT side, so one is olways "adapting" around. On ebay, the SRH805S is often sold with a male SMA connector, which according to the Diamond web site is not right. Item names do often not state the name of the antenna sold, but the pictures most often reveal a terrible try of a fake. Since most of the offers in ebay were shipping from Hong Kong or China, I just assumed a rip-off of the original SRH805S. I asked one of the sellers and he confirmed, that what he was selling was not the real deal (Diamond quality hardware) but a reproduction by a chinese factory. Since the price was in the range of my NA-701, I thought, I could give it a try anyway and ordered.
There is nothing to say about the real technical data of this antenna, because all was copied from different sources about the original SRH805S. Since I do not trust these values, when it comes to this copy, not much is said about technical data here, until a measuring device is acquired.
Chinese fake SRH805S - Some figures:
Length/diameter: 55mm / 13mm
Connector: SMA Female
Price: about 5€-8€
The Item arrived 17 days later from Hong Kong and was also packed in one of these yellow plastic pouches we all know. The pouch itself already was of a really poor quality compared to Diamond or Nagoya pouches... well... that does not say anything about the antenna performance, but it tells a lot, anyway.
That factory in Hong Kong did not mind to fake the original diamond packaging to the letter - even if smaller and in a poor quality. The Diamond logo on the pouch is very similar to the original. When I took the antenna out of the pouch, I was somehow surprised, that the copy job of the antenna inscriptions was not that sophisticated. The manufacturer did not bother the customer noticing the scam, once beyond the quite convincing packaging.
The copy was not only larger, it was also manufactured in a much less deliberate way. Not only was the copy some grams lighter, it also produced some noises while shaking and gave a much poorer haptic experience. In expectation of some measuring equipment, I was hoping to find out, how useful this one could be anyway later.
When I wanted to order another NA-701 at the Thiecom shop, I ran across another tiny multi band antenna, I until then had not heard a single word of - the Hoxin SCH-32. This antenna has a quite odd combination of transmit frequencies, it claims to be designed for: 144Mhz, 430Mhz, 900Mhz - the latter to my knowledge is not a ham band anywhere in the world. Since I was only keen on the first two bands, I was thinking about ordering one of these, too. The price was about 10€, which was only a little bit more than the SRH805S copy would cost, so I ordered and got one some days later.
Long story short, I was looking for an antenna that was short and working in the cases I needed it to work:
- Portable near field simplex (on field days, expeditions etc., 70cm and 2m)
- Repeater work (70cm as well as 2m)
When the package arrived, I was very surprised by the actual size of the Antenna:
 |
| No lie - 4.5cm |
Length/diameter: 44mm / 13mm
Connector: SMA Male
RX: 144/150/300/430/450/800/900MHz
TX: 144/430/1200MHz
Max TX Power: 10W
Type: 1/4λ
Price: 15€ to 25€
Compared to my HT, the Antenna is just tiny and looking at that, I could not imagine, how the not so well known SRH1 (2.5cm length, 2m single band tx) would look like. The also quite small TH-F7 Transceiver was looking even more portable, with that antenna on it. I really liked the look and feel of the antenna.
The antenna was shipped with a rubber spacer for HTs with quite long SMA connectors, so that the antenna body would rest on the HTs case and dampen the pressure on the delicate connector. I didn't need to use that on the TH-F7, on the Wouxun KG-UV2D with the SMA gender changer screwed in instead, it proved really useful.
I was wondering, how they would build a 1/4 wave resonant antenna and found a nice picture on google images, explaining the matter... I am not very comfortable with posting it here, but I didn't find the original source online. It shows the original construction of the antenna:
 |
| Correct me, but it looks like a coil of about 23cm of wire, center connected capacitor |
Hence possessing a Wouxun KG-UV2D as a second hand and secondary unit, I was looking for a similar antenna for that device. The unit bears the burden of a male SMA "sink" on the HT side, so one is olways "adapting" around. On ebay, the SRH805S is often sold with a male SMA connector, which according to the Diamond web site is not right. Item names do often not state the name of the antenna sold, but the pictures most often reveal a terrible try of a fake. Since most of the offers in ebay were shipping from Hong Kong or China, I just assumed a rip-off of the original SRH805S. I asked one of the sellers and he confirmed, that what he was selling was not the real deal (Diamond quality hardware) but a reproduction by a chinese factory. Since the price was in the range of my NA-701, I thought, I could give it a try anyway and ordered.
There is nothing to say about the real technical data of this antenna, because all was copied from different sources about the original SRH805S. Since I do not trust these values, when it comes to this copy, not much is said about technical data here, until a measuring device is acquired.
Chinese fake SRH805S - Some figures:
Length/diameter: 55mm / 13mm
Connector: SMA Female
Price: about 5€-8€
The Item arrived 17 days later from Hong Kong and was also packed in one of these yellow plastic pouches we all know. The pouch itself already was of a really poor quality compared to Diamond or Nagoya pouches... well... that does not say anything about the antenna performance, but it tells a lot, anyway.
 |
| Bigger antenna, smaller pouch |
 |
| Top: fake - Bottom: the real deal |
 |
| Top: the real Diamond - Bottom: poorly faked copy |
When I wanted to order another NA-701 at the Thiecom shop, I ran across another tiny multi band antenna, I until then had not heard a single word of - the Hoxin SCH-32. This antenna has a quite odd combination of transmit frequencies, it claims to be designed for: 144Mhz, 430Mhz, 900Mhz - the latter to my knowledge is not a ham band anywhere in the world. Since I was only keen on the first two bands, I was thinking about ordering one of these, too. The price was about 10€, which was only a little bit more than the SRH805S copy would cost, so I ordered and got one some days later.
 |
| even smaller than the SRH805S: the Hoxin SCH-32 |
Hoxin SCH-32 - Some figures:
Length/diameter: 39mm / 14mm
Connector: SMA Male
RX: 144/430/900MHz
TX: 144/430/900MHz
Max TX Power: 10W
Type: 1/4λ
Price: ~10€
To be honest, neither I had heared about Hoxin before, nor did I find some clues about the Antenna online. I doubt, SCH-32 is the only market name of this antenna. Its build quality is quite high despite the price. Its SMA connector looks a lot like the Nagoya NA-701 one and I would not be surprised, if the actual manufacturer was in fact the same.
Connector: SMA Male
RX: 144/430/900MHz
TX: 144/430/900MHz
Max TX Power: 10W
Type: 1/4λ
Price: ~10€
To be honest, neither I had heared about Hoxin before, nor did I find some clues about the Antenna online. I doubt, SCH-32 is the only market name of this antenna. Its build quality is quite high despite the price. Its SMA connector looks a lot like the Nagoya NA-701 one and I would not be surprised, if the actual manufacturer was in fact the same.
I am right now still very excited about testing these antennas in the field and in the lab. After some quick tests with the local repeater all three have the potential of surprising me on 70cm - on 2m they all failed me until now. I will retry this from a different spot sometime.
My hopes and cheers are right now with the Hoxin SCH-32, because it is well made, small(est of all three) and compared to other tiny antennas, its quite affordable as a stand by option, if the HT has to be as small as possible.
 |
| ltr: Hoxin SCH-32 / Diamond SRH805S / Chinese SRH805S copy (SMA female) |
Stay tuned for some hard facts from the field.
This will be interesting. My fake Diamond SRH805S proved to have a minimum SWR at 169MHz. I bought a similar Comet antenna which was a good match although the performance was not very good. I sold that when I switched to BNCs with adapters on all my radios so I could change antennas at will without problems with the SMA center pin, but I couldn't in all honesty sell the fake as a 2m antenna so it's currently used for the 10mW TX in my APRS weather station.
AntwortenLöschenI now have three BNC antennas of this type, two unbranded from China and one from Thailand. They were all cheap, and all a good match. My attempts to measure their performance suggest they are 3 - 4dB below that of the typical stock rubber duck but I'd be surprised if they were really as good as that. I await the results of your tests with great interest.
Any updates on the antenna measurements?
AntwortenLöschenYes, there are... Sorry for the late reply, but I was busy with Housekeeping ... :/. The Fake device is worth nothing on 2/70, its a worse pick in every way over the original. I did until now not do any real measurements, because the equipment is not affordable right now, but let me tell you that the SCH-32 and the SRH805S feel the same - either with an adapter on the Wouxun or without on my TH-F7. They work fair enough on 70cm, not very well on 2m (and should not be used for that, I think). In no means these antennas are capable of replacing a "classical rubberduck" dual band antenna. Therefore for non-local or repeater-work I will stick with my Nagoya Rubberduck.
AntwortenLöschenI just received one of these antennas as well:
AntwortenLöschenhttp://m0mln.wordpress.com/2013/02/15/fake-diamond-antenna/