SRH805S Diamond Antenna

[rob42]

I suspect that my GT-5R is not transmitting on the displayed FREQ (if that's possible). Well, that said, it seems to be good on some FREQs, but not others (again, if that's possible). It's a little hard for me to tell for sure, as I don't have any way of testing this, aside from my UBC125, which simply goes bonkers, even if the GT-5R is on its low power setting and 'Narrow Band'. I can't say if this is happening if I'm out sight of the scanner, and I've nobody else here at the time of day that I'm doing the tests.

Is it that the UBC125 is getting 'swamped', or do I have a faulty GT-5R? Maybe that's not an easy question to answer.

I've had a thought: before I condemn the GT-5R, I'd like to do some more tests, but with the TX range throttled as much as possible. Would the SRH805S Diamond Antenna restrict the TX down to a range that would only be picked up by a station within, say 1 mile or so, maximum?

SRH805S.png

Right now, I'm not doing any testing at a time of day that would bother anyone else in my area, but that's very limiting for me. I'd like to get to know my HT and the only way that I can do that is by using my receiving station to monitor what I transmit.

Thoughts and/or comments, please, gentlemen?

P.S: just so that you don't think that I'm using the Antenna listed in my sig, the NAGOYA NA-771 is pending; it's on its way and I expect to have that before this week is out.

[Antoni]

It could be that your scanner is not healthy - probably fine but it's something to consider.

Sorry to state the bleedin' obvious but a bit of test gear would go a long way here. Do you know anyone with such locally? You don't live near Mansfield do you?

You can do the testing in the same room by simply protecting the scanner from the very strong transmission.
You have to allow the scanner to work as it does in the real world - with weak to moderate signals - try to simulate that.
Most important that you have no antenna connected to your scanner - there is even the possibility of damage to it else.
At that close a range the internal wiring of the plastic-cased scanner will work as an antenna. Maybe try the tin-hat brigade approach and wrap the scanner with baking foil such that you can see the display. If you can hear the wanted signal from your transceiver - but absolutely nothing else anywhere else, your scanner should not be being 'swamped' by the transceiver with no antenna on it, and work normally.

[rob42]

It could be that your scanner is not healthy - probably fine but it's something to consider.

A very good point: it's not improbable, but it is unlikely, as I seem to be receiving all other RT on the expected FREQs.

Sorry to state the bleedin' obvious but a bit of test gear would go a long way here. Do you know anyone with such locally? You don't live near Mansfield do you?

You're bang on the money, and you'll know just how expensive that kind of gear is.

I guess that one of my local Radio Societies may have testing equipment. I will need to make contact with one of them soon, so that I can sit the Foundation examination. It seems (to me, least ways) to be a bit of a liberty, to simply rock-up and ask them to test my Radio, and I'm really not too sure that I'd want to become a member of a club just now; social anxiety is a thing with me and I'm very opinionated, which many people find off putting, and I find very difficult to control.

Thanks for the offer, but no; Mansfield is the better part of 150 miles south of my QTH.

You can do the testing in the same room by simply protecting the scanner from the very strong transmission.
You have to allow the scanner to work as it does in the real world - with weak to moderate signals - try to simulate that.
Most important that you have no antenna connected to your scanner - there is even the possibility of damage to it else.
At that close a range the internal wiring of the plastic-cased scanner will work as an antenna. Maybe try the tin-hat brigade approach and wrap the scanner with baking foil such that you can see the display. If you can hear the wanted signal from your transceiver - but absolutely nothing else anywhere else, your scanner should not be being 'swamped' by the transceiver with no antenna on it, and work normally.

Now, there's something that I can get a handle on. I really don't need to see the scanner display, as the software that I use has all that covered. The antenna is right out of the way; it's in the loft. That said, I am in the room that's directly below. I'd not thought about any damage protection screening... humm... So, I could build a simple Faraday Cage (I know a little, about a lot) and pop my UBC in that, maybe with an open top, so that I can still receive some signal with the antenna disconnected?

It's maybe worth a mention: I have a Oscilloscope, not an expensive one, but it served the task at the time, and I've not used it since. I have done some searching (internet) with regard to using my scope for Radio FREQ analysis, but the results seemed to be a little outside of my skill set and I'd not what to damage my scope; it was not too expensive, but it was not free of cost, either.

You've been a great help; thank you.

[Stronty]

Good advice and its always troublesome when equipment is limited. I'd say don't purchase any more antenna's as the one you have coming The NA-771 SMA will be fine (well if genuine, i.e. not in an orange sleave and proper QR codes, comes with washer and is smooth slopped at the bottom 2 cm+ and not a rounded step) the antenna that comes with the radio is usually barely sufficient.

What TX is it good on?
What TX is it bad on?

Is the conclusion solely based that the displayed frequency on the radio and the transmitted frequency is different because you are just testing against the UBC125?

In 2 way comms on PMR frequencies are you good? anyone with a cheap pmr can help with that. Clearly you are not able to transmit officially on amateur bands until licenced of course

If you have programmed using Chirp, have you used and existing Db (list) to upload to your radio? some channels/pre-set frequency lists will have offset TX / RX set so not the same frequency (you Transmit on 1 frequency and receive on a slightly different one)


You maybe know all of this, so again apologies.

[rob42]

Good advice and its always troublesome when equipment is limited. I'd say don't purchase any more antenna's as the one you have coming The NA-771 SMA will be fine...

Thank you for your reply. As it turns out, I've made a rookie error: the NA-771 has just dropped in (from Lindars Radios; yes it's a genuine NAGOYA, thanks for asking), but I neglected to check the mount, which is a M-SMA. No good for my GT-5R, which requires a F-SMA

Oh well, it'll come in to use at some point down the road, I guess.

I'm going to do some more testing when almost everyone else is sleeping, so that there's far less chance of me causing any trouble to anyone else.

With the HT on low power, and the UBC in a Metal Box, I'll not be out doors in any case, this time, but even so, if nobody hears me, nobody can complain.

I'll compile my findings and report back. It's as likely as not that it's me that's at fault, not my equipment; right now I'm just

But, this is a good thing, as it's a superb learning opportunity.

Edit to add: I will be using CHIRP, just as soon as the Programming Cable drops in; that is unless I've messed that up, also

[Stronty]

Thank you for your reply. As it turns out, I've made a rookie error: the NA-771 has just dropped in (from Lindars Radios; yes it's a genuine NAGOYA, thanks for asking), but I neglected to check the mount, which is a M-SMA. No good for my GT-5R, which requires a F-SMA

That's a pity, though I genuinely wonder if it is indeed a genuine Nagoya if it is priced at £8.00.

Na-771.jpg

Usually around £18.00 to £24.00, but i hasten to add spending more does not rule out fakes.

it should be cone shaped rather than stepped, older versions were stepped but they are very very old stock if even still around.

That would be grounds for returning it at no cost to you.

Anyway best of luck confirming your TX and hope you have a working radio.

[rob42]

Yeah, that's the one. It's a used item, hence the price, I guess. Lindars has a good reputation, so far as I know, but yeah, I'll return it, if it's fake.

Can you tell from this?

20260805_155819.jpg

Sorry it's upside down.


A thought occurs to me: I'm uncomfortable with the idea of having the antenna real close to my head, so I'm going to get an extension hand-held Mic. Could the NAGOYA be converted into some kind of a Mag Mount, or does its design prevent that kind of a mod?

[Stronty]

Yeah, that's the one. It's a used item, hence the price, I guess. Lindars has a good reputation, so far as I know, but yeah, I'll return it, if it's fake.

Can you tell from this?

20260805_155819.jpg

Sorry it's upside down.

Ah! second hand may explain the reduced cost. That looks conical so that's a good sign and the N and the A look good on the font, I'm afraid that looks genuine (assuming the QR code thats stamped is under the price sticker.) what a pity.

For less than £3.00 though you can make it work. SMA FEMALE to SMA FEMALE, Add a couple of rubber grommets, they originally came with one in the genuine Nagoya package anyway.

sma female to female.jpg

[rob42]

Thank you very much for your attention on this; much appreciated.

I've removed that price ticket, but it wasn't covering anything up, least of all a QR code. If the genuine items have a QR code for sure, then it's a bit of worry that this one does not have one; no rubber grommets with it, either.

I'll get one of those SMA F->F adapters, and then maybe go and pester the guys at a local club and see what they have to say.

At worse, I can put it aside for when I either find a use for it, or sell it on, at cost.

[Stronty]

Sounds good, and if you're staying on or around those bands it might be worth getting a SWR/PWR meter for 140>500Mhz. That will certainly help figure out if your antennas are what or where they should be. But again at a cost.

P.S. I own the NA-771R with is the retractable version and have owned the one you have and it was a total learning curve (Fakes etc.) just to get a £25.00 handy working better. I must say though, effort pays off. far better than the stock Baofeng antenna and better than the fake one i got at one point.

[rob42]

I've run some basic tests and I think I've a better idea about what's going on.

On the first test, I had the scanner hooked up to a computer via the USB lead, so that I could see (on the computer screen) what the scanner was receiving , which is in a closed metal box, with its stock antenna. There's a small gap between the lid of the box and its body, where the USB lead comes out, so that some signal can get through, and maybe enough to cause the scanner to be swamped by the RF radiation, as the radio FREQs were not what the GT-5R was showing on the TX.

For the second test I had the idea of using the Close Call function, so that I could seal the box lid: no signal got through (thank you Mr. Faraday. You are one of my heroes from history).

So for the third test, I had to again have a lead to the scanner, but this time it was the Antenna Coax that runs up to my Moonraker, in the loft. With the scanner still in Close Call Mode, I can hear the classic squelch sound at eot, as well as the 'Rodger' beep that my GT-5R is transmitting.

Checking the results (it only save 10 CCs at any one time) seems to show all the FREQs as being correct. Again, hooking the scanner to the computer, as there's now, once again a gap between the box lid and the body, caused by the coax, shows crazy results again.

So, this would suggest that it's the USB connection that's causing the FREQ errors; it's a quality lead and even has a chock fitted. The only other thing I could do, in the absence of lab equipment, is to have a Faraday Cage that's large enough to house both the scanner and the computer, but that seems like a lot of trouble to go to, just to prove a point.

In conclusion. I now believe that the GT-5R is just fine, and it's RF interference that's causing the FREQ errors in the system. It's late, I'm tired, and I can't be running up and down the street outside, using the PMR band right now, so I'll jack it in and maybe do that another night.

Just to add: the FREQ errors seem to be with VHF, rather than UHF signals, but my tests are less than scientific, so there's that.

[Stronty]

great news. try sticking a couple of clip on ferrites to the USB lead to complement the one that's there, if you have them, even a core with the USB tightly wrapped round it a few times maybe.
other than that, I'm sure you feel satisfied with your results.

[rob42]

I'll have a dig around and see what my hording can provide; there's got to something of use.

Well, I'm now far less worried about what the GT-5R is putting out, in terms of its RF TX. I understand that the top of the 2m Spectrum (146 - 148 MHz) is intended for Emergency Service communications, so I'd not want to interfere with anything there. That aside, there are very obviously, less concerning, but still legitimate reasons why I want to be very sure about what I'm doing, while 'on the air'; it's all too easy these days to simply take the tech for granted and treat like some kind of an extension to the mobile phone network.

It has been good to be able to focus my thoughts by writing about it all, here. Thank you for your help and advice (my thanks also to the guys that operate these Forums) and you never know, we may even QSO at some point in the future.

[paulears]

It is worth mentioning that Nagoya 771 antennas are not really understood. In China, the 771 design is treated as an open design. There is no Nagoya factory, the antennas come from much smaller companies, and if they make antennas, they will be the Guangzhou Nagoya antenna company Ltd, or the another company name with Nagoya in it as a name. A bit like people in the U.K. calling vacuum cleaners Hoovers, despite being made by Dyson!

All these antennas are made by the firms who specialise in simple electronics encapsulated in floppy rubber. Their skill is injection moulding, using state of the art kit. The green colour packet is not important. They switch to yellow in the afternoon when they start to make Diamond. Sometimes, the swap over is not clean and a batch arrives mostly green but with some yellow. It means nothing. The screen printing is also a process that is prone to errors when they go too fast, or the worker misaligns it in the jig. It is a generic design, NOT a brand. There will also be failures. Usually soldering at the base. What happens is we look at the sleeve, the printing and the VSWR and shout loudly genuine when one works and if you get a lemon, you shout fake. They could be made by the same person. I don’t sell them any more, but I do sell a range of marine ones and amateur ones. They are very similar to diamond. Inside virtually identical, but they have marine grade fibreglass tubes and seem to last really well. Sometimes they come in Diamond branded sleeves. But they gave me some spare blank ones. I sell them as my own brand. This means that every antenna made in China is suspect when you use our understanding of companies. Imagine a well thought of British company. That name will almost certainly be used in China for branding. With and maybe without permission. I bought one Chinese brand of marine radio. Then I discovered that it was made by a different firm. That factory sold it under four brand names, and best of all, they would sell to me if I ordered in quantities greater than ten units. My original ‘factory’ was a desk in a huge complex. They ordered in, and posted out. The antenna people who are specialists at moulding are in a building where their products are fabricated and then individual offices (which have Diamond or Nagoya in their name) sell them. One has within in it, packaging companies, screen printing businesses, injection moulding companies and even logistics people. If you want an antenna, flag pole, usb stick or battery, everything is there in one building. Clever!

[Stronty]

Thanks for the additional info, very handy. As far as the "Nagoya" brand and in particular the NA-771 (there are others of course) there are multiple sources and some very distinct copies ("fake" is just another way of saying that) imo. I had always took it as REUEX INDUSTRIAL Co Made in Taiwan as the source of originals. Same place that make REVEX kit (SWR/PWR Meters etc).

Almost impossible to guarantee something bought via eBay, AliExpress, Amazon or elsewhere will originate from there of course. But the well documented differences in appearance and technical specification and testing do, to some degree provide the buyer with a suite of information to limit the chance of getting a complete dud.

NA-771 Data+sheet.pdf