• Who makes these?

Posted: **Fri Jan 17, 2025 6:32 am**

Do you mean RD06HVF1? I have never heard
about RD01HVF1. However, RD01MUS1 is a 1.4W device.

Posted: **Fri Jan 17, 2025 1:00 pm**

Albert H wrote: ↑Thu Jan 16, 2025 11:29 pmThe circuits I used were my four-IC PLL, a Colpitts oscillator, balanced doubler, and an output stage using a BF199 into a 2N4427. The stereo coder was based on the NRG Pro III coder, but with a better output filter, The stereo limiter used a TL074 quad op-amp, a couple of transistors and a pair of LCR0202 vactrols. I use a 4MHz reference crystal (cheap as chips!), and all the coils are hand-wound. The most expensive single component is the 2N4427 - you have to shop around to find genuine ones!

I know the sort of thing and can imagine the prices are pretty close to the mark. I was including my PCB and inductors in my breakdown and these bump the price up quite a lot. So it's:

Resistors (48) £1.80
Ceramics (70) £3
Electrolytics (7) £1.70
L's (20) £6 (only 2 of these are RFCs)
silicon (20 items) £8.50
Xtal (1) £0.20
pushbutton (1) £0.78
PCB (1) £5
4 PCB headers for power, MPX in, remote enable and ICSP. Not using an RF connector.

Remember this is just the exciter though!

My most expensive component is the microcontroller, £2.32 from RS. No components have gone obsolete however the PLL I'm using has been around for 20 years.

Also, I've calculated the values "per item", haven't counted P+P and might have omitted VAT on some. Obviously if you were just making one it would be way more as many components, even the PCB, you can't buy singly. My dev costs are probably in the hundreds not counting my time, and I'm not even at v1.0 yet, this is prototype iteration #3. I've a fair bit of apathy about traditional FM and keep losing heart, so this one I keep dipping into when my enthusiasm for it comes back.

Posted: **Fri Jan 17, 2025 4:49 pm**

zulu53 wrote: ↑Fri Jan 17, 2025 6:32 am Do you mean RD06HVF1? I have never heard
about RD01HVF1. However, RD01MUS1 is a 1.4W device.

Yeah thats a typo. I was thinking of rd01mus1 too but thats smd and I figured Albert was trying to stay through-hole for a kit.

shuffy wrote: ↑Fri Jan 17, 2025 1:00 pm No components have gone obsolete however the PLL I'm using has been around for 20 years.

What PLL are you using? I thoughts all the good ones for FM band (saa1057, mc145xxx) went obsolete years ago. Last time I looked there was still some stuff from TI and AD but they all had min input frequencies >100mhz and aren't cheap either. Of course 7400 logic is still an option

Posted: **Fri Jan 17, 2025 5:12 pm**

It's an LMX2306. Not looking forward to soldering the bugger!

Posted: **Fri Jan 17, 2025 6:04 pm**

Actually I tell a lie, it has gone obsolete. I bought a strip of them a while back and I've had this design kicking around for a few years now. For the sake of being current (i.e. what would I choose if I was starting the design from scratch?) I'll have a look through mouser or digikey and see what jumps out as suitable!
Edit: verrry quick look on Mouser and ADF4001 looks remarkably similar to the LMX2306! 2006 vintage though so I doubt these will last much longer.

Posted: **Sat Jan 18, 2025 1:22 am**

Pricey little fucker too and needs external ref osc, can't just hook up a crystal

Longer I look at it the more I think Albert has the right idea with his cmos logic. Cheap as... well... chips and i bet you can still get them in 30 years time

Posted: **Sat Jan 18, 2025 2:43 am**

A pal of mine in Ecuador had a problem with getting the quicker 74HC logic ICs. He reverted to my (much) older way of doing his PLL using an SAB6456, set to divide by 256. He then used ordinary CMOS at around 400 kHz for the rest of his PLL. The prescaler IC is widely used in TV tunerheads, which is where he got the one he used, and he also scrounged a couple of the transistors for his oscillator, buffer and doubler stages. He reckons his whole 5 Watt exciter (using a Mitsubishi "6 Watt" FET) cost him around $12 (US).

He's building a transmitter for use near his town, and thinks that he'll need about 60 Watts or so to get the coverage he wants. He plans to use a couple of stacked "H" aerials to give him hemispherical coverage, and to give a useful bit of antenna gain. His only limitation with the site is that it has to be battery powered, with the "leisure" battery charged by a small wind turbine and solar panels. Luckily, there's mobile phone coverage at his site, so he plans to link "over the 'net" to get the programmes there.

I've also provided him with some ideas for battery charging controllers - it's an interesting project, and I hope that it works out for him.

Posted: **Sat Jan 18, 2025 8:04 am**

Ah, Ecuador and powerless site sounds much easier than our 3-4month darkness...

I have been wondering, do I need to build an FM rig? I dont need one, but everyone is building one, so why not?

Posted: **Sat Jan 18, 2025 5:53 pm**

jvok wrote: ↑Sat Jan 18, 2025 1:22 amPricey little fucker too and needs external ref osc, can't just hook up a crystal

Yeah, they're a few quid (assuming you're talking about the more "modern" AD ones). The LMX's still seem to be quite common and you can get them for pennies from China. True they need an external osc, same as the AD ones I looked at, but as you're going to need an MCU to program the thing, just clock that using the crystal and feed the PLL REF_IN from the CLKOUT pin (assuming you're using a PIC) which will work OK as long as you don't load it too much.

Incidentally the last exciters I made in any volume used MC145170D2 with a PIC12F629 controlling everything. The PLL chip had the XTAL on it, and the PIC was using its own internal oscillator as I needed to use every non-supply pin on the damn thing as I/O. So on this later one, the PIC's providing the clock reference.

I guess what you end up with, depends on what you're trying to do. For me, this exciter design was all about shaking the RF side up a bit, not about the PLL. I just changed the PLL as I knew the MC145* were obsolete and I tend to want to work those out of my designs. I got caught out on the LMX2306 though... oh well. I'll change that on the next one!

jvok wrote: ↑Sat Jan 18, 2025 1:22 amLonger I look at it the more I think Albert has the right idea with his cmos logic. Cheap as... well... chips and i bet you can still get them in 30 years time

I was having a look whilst thinking about less highly integrated PLL architectures on that other thread recently which started out being about prescalers. I do reckon it's slowly getting harder to find some of those 74 series chips, especially in the old DIP packages. Finding a divider certainly didn't look as easy! Because of this, and looking at the production life of some PLL chips of the past, I just thought maybe a more current PLL is the way to go. Lots seem to be oriented towards GHz applications but as long as it will clock down to VHF then a PLL is a PLL. Also I'm not expecting to have to repair one of my exciters in 20 years' time

Posted: **Sat Jan 18, 2025 9:23 pm**

shuffy wrote: ↑Sat Jan 18, 2025 5:53 pm I was having a look whilst thinking about less highly integrated PLL architectures on that other thread recently which started out being about prescalers. I do reckon it's slowly getting harder to find some of those 74 series chips, especially in the old DIP packages. Finding a divider certainly didn't look as easy! Because of this, and looking at the production life of some PLL chips of the past, I just thought maybe a more current PLL is the way to go. Lots seem to be oriented towards GHz applications but as long as it will clock down to VHF then a PLL is a PLL. Also I'm not expecting to have to repair one of my exciters in 20 years' time

Can still get 74ahc74 (for prescaler), 74hc4020, 74hc4060 and 74hc4046 in dip packages, thats all you need to do a pll and probably costs <£1.50 total

Tbh I've given up trying to use dips nowadays I just design with smd and get jlc to assemble for a few quid. Go that route and you can still get 74hc4059 for your divider although not that cheap

Posted: **Sat Jan 18, 2025 10:12 pm**

jvok wrote: ↑Sat Jan 18, 2025 9:23 pmCan still get 74ahc74 (for prescaler), 74hc4020, 74hc4060 and 74hc4046 in dip packages, thats all you need to do a pll and probably costs <£1.50 total

I was about to suggest the same combo on that other thread with a 4040 (with diode trick) instead of the 4020. I wound my neck in as everything I thought of was steering back in the direction of Bradford

Using an XOR gate (7486?) as a phase comparator does have advantages too.

jvok wrote: ↑Sat Jan 18, 2025 9:23 pmTbh I've given up trying to use dips nowadays I just design with smd and get jlc to assemble for a few quid. Go that route and you can still get 74hc4059 for your divider although not that cheap

Yep - no going back after you try it!

Posted: **Sun Jan 19, 2025 12:24 am**

You are right of course its 4040 not 4020, been a long while since I played with anything like that but I think it still has legs if you want to put the effort in

Tbh I never really understood the pros and cons of 4046 vs 86 as phase comparator. Something about lower phase noise vs easier filter design I think. I always went for 4046 as you can feed it with 50% duty, makes divider circuit a bit simpler

Posted: **Thu Jan 23, 2025 2:12 pm**

FMEnjoyer wrote: ↑Tue Jan 14, 2025 5:24 pm please refresh and I wonder what oazzz has to say about these findings as he said his one was nice and clean, this shows not.

Once again I repeat. From the GD-2015 transmitter in a range of 88-108 mhz I do not observe hindrances. In a range above 108 mhz of hindrances too is not present. On an exit of the transmitter there is a good filter!

Posted: **Thu Jan 23, 2025 5:03 pm**

That is not harmonics or out of band spurious, I am not a radio techhead really, but I see 600kHz span that's the audio profile either side of carrier ?

I think the problem is you see the Chinese boxes and then when they come filtering and shielding is missing and that then can mess
them up. Even if the chip has a low spurious and harmonics in the spec sheet once amplified from 1mW to 10 or 15Watts if any shielding and filtering is missing to save manufacturer costs then they do not at all have the same spec as the chip itself. Then QN8007 might be good audio and lowish spurious and harmonics but why is EFR's spectrum showing terrible, terrible performance. He would not lie I think.

I noted in one of your pictures of the GD2015 that the filtering was missing from the RF output transistor stage and on advert for GD-2015 it shows multiple coils (6)

Oazz do us a favour and show a 100pct creditable spectrum scan on video, with all RF wires shown going into you analyser and 10W coming out of it at least and show all harmonics and spurious in a continuous scan from 30MHz-300MHz

It is easy to falsify these spectral analysis and showing it with honesty is in your interest if you are the seller, seems like it.

Until then we know EFR has no reason to lie.

2 images....

Your photo posted on this forum some weeks back of GD-2015 - 3 coils near RF output transistor..

https://ibb.co/LRZYYNP

In advert 6 coils

https://ibb.co/3TZ2nQV

So you did not get what was advertised if you did in fact buy it. 3 coils are clearly missing than the advert, I can see that with my own eye balls. Do they remove components in China as they wish to to increase profit margin ? It seems so. That is not good and maybe explains why EFR analysis shows VERY bad spectrum.

Truth is we do not want to interfere over here, even the pirates. We all need fire, police and ambulance, aircraft to work well.

Posted: **Thu Jan 23, 2025 5:51 pm**

Those are 2 different board layouts - look at the other components too not just the coils! The round devices to the right with the ferrite cores are RFCs, typically in the drain circuit for supply and don't form part of the RF path. Two are visible in one pic, one in the other. So there are 4 actual RF coils visible in both pics.

These manufacturers are always changing their boards every 5 minutes! Perhaps there's not much science going into the RF design and it's trial and error in some areas? The outrageous stretching of the coils adds weight to this view - it's valid, but I don't like it. There's quite a bit that I either don't understand, or don't like, about his layout in that area actually. Don't like much really, do I?

Would be nice to see a circuit so we can see what it's trying to do.

Posted: **Thu Jan 23, 2025 7:59 pm**

Sorry I was wrong on all this. All I was optimistically hoping for is 500mW, PLL, Stereo, minijack / SMA off 5V USB C. That would be very interesting, the potential could be with a bit of imagination as I am sure you can think through.Seems it is too much to expect, I have no clue what I am talking about on the anorak side so will stick too listening.

Posted: **Thu Jan 23, 2025 8:13 pm**

I returned my unit, wanted my money back from it.

I think there also will be some quality control issues on these rigs, one might be good, second one might be assembled by another person and be horrible.

Do they just build and box them, or do they test every unit agains SA?

Can You Oazz check Your unit like 40-400Mhz with least 10kHz RBW?

Is it stable if You run it agains diffrent loads?

Posted: **Thu Jan 23, 2025 8:25 pm**

FMEnjoyer wrote: ↑Thu Jan 23, 2025 7:59 pmSorry I was wrong on all this.

Not at all - you're quite right the devices in the 2 pics are different and therefore at least one of them will not have been as advertised! I agree it would be interesting to see a wider spectrum from oazz rig if possible. I'm not really interested in rigs of this sort but as I think EFR has alluded to, there does seem to be a fair amount of inconsistency in the design and manufacture.

Posted: **Fri Jan 24, 2025 7:07 am**

In detail about the transmitter I already told at forums. I am not a seller!
The transmitter which I bought GD2015 me completely arranges. Excellent sound and lack of hindrances. Who does not trust can buy and be convinced it.

Posted: **Fri Jan 24, 2025 8:10 am**

oazz wrote: ↑Fri Jan 24, 2025 7:07 am In detail about the transmitter I already told at forums. I am not a seller!
The transmitter which I bought GD2015 me completely arranges. Excellent sound and lack of hindrances. Who does not trust can buy and be convinced it.

So You got much better unit what I did, some quality control issues then.

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