Hello Steve,
Afraid I support the all bands camp. With a Hexbeam and 80/40/30 wire antenna I like to be able to use any band and work the warc bands under heavy contest conditions. I operate remote from my hardware and trotting out to change filters is not a good option for me. Regarding the filter arrangements I think you have laid out the pros and cons pretty well but I lean to Peregrine switches on the Rx filters and PIN on the Tx. Claudio's suggestion of parallel low power low cost genuine PIN's looks like a great idea and certainly should be investigated. There is no particular need to involve the Tx filters on Rx unless it is desired to have selectable wideband rception for skimming etc. At present none of the radio software support being abe to select the Hi pass and Lo pass filters on the fly but it would be easy to add particularly using the command window you referred to on an earlier post. I would really like to see the HL as a basic unit coming out as the present 1.42 version does on one board and the 5 watt PA and filters come out on another board with all bands. Whatever size is needed to accomodate this is the final size of the unit. For my personal part I would just want the HL board and would roll my own PA and filters as there seems to be too much variance of thought on how they should be.
73, Graeme ZL2APV
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Yes, I plan to wait to see more of the new main board prior to
making any new efforts. I am quite happy with your direction on
the list of differences.
On the RX, Alan does not have one of my RX boards so his
measurements must be with some other filter. He has a superband
that I built for 60/40/30/20 that has shared BPFs for filtering so
perhaps that is the source of the filter measurements.
I have been busy with summer farming and thus note that there are
extensive cobwebs on my workbench in the shack. Looking forward to
cooler months and more time to tinker. Glenn and Graeme did all of
the testing on the RX board. There is a list of circuit changes
that Glenn provided that need to be made if we decide to do
another pass, as well as documentation updates for the filters
that were tested by both Glenn and Graeme. For now it is on hold.
John
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I am surprised that you use only +6 dB gain. According to the measurements by AB4OJ, the minimum detectable signal for the HL is not on par with other radios until the LNA is in the +18 to +20 dB range.
Hi List,
If I restate what I hear you saying, is that in noisy environments, +6 dB of gain is enough as the HL noise floor will still be below the higher ambient noise, and if you increase gain you are just amplifying noise.
Maybe this is true for SSB signals decoded with a human ear, but for modes like WSPR, JT9 and JT65, where the signal can be 30 dB below the SSB noise floor, it seems more gain is beneficial so that weak signals even register with the ADC.
Hi Claudio,
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Hi Claudio,Thanks for investigating the BAR64 and the SKY13374-397LF. I look forward to learning what you find.73,SteveKF7O
Hello SteveI instinctively support your view, but I cannot give any good 'scientific' reason. We should not forget that the 'band noise' is not white noise but a complex mixture of large and small signals of all kinds which sounds to our ears like noise, but from which signals can be extracted.To play a bit further on the 'cranking up the audio' analogy.............if you are listening to an orchestra and you crank up the audio, the signal to noise ratio stays the same, but you can likely hear better an instrument that is playing more softly in the background.Perhaps a better question to ask is whether there is the downside from keeping the majority of the bits filled in the A to D?73Robert G3WKU
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Hi Claudio,
As far as the narrow band noise floor is concerned, my understanding is the optimal gain works out the same as long as you use the same bandwidth for measuring the radio noise and the band noise but I'm happy to be put right on this.
If you set the gain so that the ADC is barely clipping on the strongest
signal (which is the best you can do regarding quantization noise), for
10bit, the quantization noise is roughly 60.2dB below the strongest
signal. For 12bit, it's 72.24dB.
It's not uncommon to have an RF noise floor around S5 (in 2.7dB
bandwidth, S9 = -73dBm)
in many bands in urban locations. In quite rural
locations the noise is even lower. With this RF noise floor, a signal
stronger than S9+36.2dB will raise your noise floor due to quantization
if you use 10bits. If you use 12bits, it's S9+48.24dB.
On bands with lower noise all bits are used
73,
Steve
KF7O
73, YO8TFF
Trimis de la: YOGA Tablet 2-1050L
Pe 26 sept. 2016 09:01, Steve Haynal <softerh...@gmail.com> a scris:
>
> Hi List,
>
> Below is the latest picture of the HL2 pcb layout. Some comments:
> The routing is essentially done. Only 17 signals (14 digital, 3 RF) plus some powers and ground leave and continue to the right.
> There is still silk screen cleanup and some double-checking and tweaking for DRC and EMI.
> This was a lot of work to do by hand! It is pushing the size limit of what I'd want to do with KiCAD.
> Because the increased number of voltage supplies (3.3, 2.5, 1.2, plus several islands of each voltage) on a single inner layer of a 4 layer board would cause many power plane discontinuities, and because I want to make best use of the decoupling capacitors on the back by routing power->capacitor->via->IC power pin rather than power->IC power pin->via->capacitor, I decided to route the power on the outer layers and have two inner ground planes. Rob KL7NA built a fork using this PCB stack-up and there were no detrimental effects from this change.
> There may be too may decoupling and bulk capacitors in this layout, but I'd rather have footprints for them and leave them off later if not necessary.
> This week I will work on the OPA2677 layout, staying close to what Jim did.
> There are optional items for the middle space (slow ADC for SWR/PWR and temperature measurements, digital bias for PA, bus expander) that I am considering for the middle.
> Space for the 10V supply for the OPA2677 is reserved. I am considering making this a dual layout. One can build with a high current switching supply here that can then be used for the 5W AirFast PA that Claudio tested, or a simple LDO if only low current is required.
> I am experimenting with a filter layout that I believe will fit and provide 6 LPFs for TX on a 10x15 cm board. I will share this soon. My first choice is still to have everything on a single 10x15 cm board with good optional connections for external filters and PA if desired. (This option would require the builder to just leave off the onboard filters and PA.) I will forgo the cut at 10x10cm if I think I can fit everything I want on a 10x15 cm board.
>
>
>
> 73,
>
>
> Steve
>
> KF7O
Hello Steve,
no, I didn't test at 500 MHz, mine was only an assumption, thinking that if the device was good for 39 dBm below 500 MHz they would have stated that, as they did for the gain, which is specified starting from 300 kHz.
I do not have a power source at 500 MHz, I can maybe get 5 W or so in the 70 cm band, or a higher power in the 23 cm band. I can anyway try at 30 MHz and see how the device behaves there.
73 de Claudio, IN3OTD / DK1CG
On Tuesday, September 20, 2016 at 5:50:03 AM UTC+2, Steve Haynal wrote:Hi Claudio,Thanks as always for your measurements. Are you certain that the SKY13374-397LF can't handle 39dBm until the specified 500 MHz? I am wondering if the drop off actually occurs somewhere in the HF bands and if this device is usable for some HF bands. You could measure at 10M and see if there is any hope for that band and then if so, for lower bands.73,SteveKF7O
Hi,
I saw on schematic în PA sheet exist 7 filters with 14 relays HK4100. I think is possible to use a half from this somethink like this http://www.tme.eu/ro/details/im06gr/relee-electromagnetice-miniatura/te-connectivity/2-1462037-3/
Or http://www.tme.eu/ro/details/rsm850b6112851012/relee-electromagnetice-miniatura/relpol/rsm850b-6112-85-1012/
This relays is bistable/latching so we can make some economy to power this and we powered only one coil and have double contacts în comparation with HK410073, YO8TFF
Trimis de la: YOGA Tablet 2-1050L
Pe 26 sept. 2016 09:01, Steve Haynal
>