A few G2 hardware questions

[KC2QMA]

-What is the exact model or specs of the fan in G2 100w? (Volts, Amps, CFM, size)
-What is the TRS balanced mic input reference level? (Typical is -10db or +4db)
-What is the TRS balanced mic input impedance? (Typical is 100-600ohms)

Side note:
I believe the TRS balance input on the G2 100w may need some internal RF choking with ferrites or small capacitor across the input as I believe I am detecting a low frequency audio oscillation below 30hz in the mic preamp even into a dummy load with no mic connected.
No issues with 3.5mm mic input.
I will have to do more research on this to confirm.

[w-u-2-o]

-What is the TRS balanced mic input reference level? (Typical is -10db or +4db)

You are referencing the standard maximum line input levels, more specifically -10dBV (+2dBu) which is typically found on consumer equipment, and +4dBu (+1.8dBV) which is typically found on professional equipment. (Note: the only difference between dBV and dBU is that dBV is referenced to 1V and dBu is referenced to 0.775V).

Unfortunately there are no equivalent standards for mic preamp standard maximum input levels. As it happens, many mic preamps have maximum standard input levels similar to line inputs.

Looking at the G2 schematics (which Apache has asked not be publicly posted, but as an owner you can request a copy), it appears the maximum allowable mic input level is -21dBV (-18.7dBu).

This is based on the circuit design being comprised of an NE5534 op amp in differential, non-inverting, single supply configuration and having a gain of 10. This is followed by a TLV320AIC3204 CODEC chip. This is significantly different than the TLV320AIC23B used in previous ANAN designs. The 3204 is in a configuration that allows a maximum, single-ended 0.9V audio input.

-What is the TRS balanced mic input impedance? (Typical is 100-600ohms)

Typical professional, balanced mic, differential input impedance is in the 1 to 3Kohm range. Unfortunately the G2 design has a differential input impedance of 20Kohms. That's pretty high, and may have something to do with it's sensitivity to RFI or EMI.

Side note: I believe the TRS balance input on the G2 may need some internal RF choking with ferrites or small capacitor across the input as I believe I am detecting a low frequency audio oscillation below 30hz in the mic preamp even into a dummy load with no mic connected.

The schematic shows a L-C Tee filters (FL1 and FL2) on both differential mic input lines. Unfortunately there are no component values shown on the schematic so its properties cannot be calculated. A Tee filter is present on nearly every input on all Apache-built SDR boards from the Hermes to the Saturn. It's a good bet they are all the same. This includes the 3.5mm mic input on the G2. Since that filter seems to work well otherwise, any RFI problems are more likely to due to other reasons, such as the aforementioned high input impedance, or perhaps the susceptibility of the NE5534.

My own side note: the schematic shows the balanced mic preamp board having a 5 pin header as the audio input. It makes provision for a phantom power (mic bias) input on pin 4. Assuming FL1 and FL2 are appropriately rated it might be possible to feed a proper 48V professional phantom voltage to a condenser microphone. The DC blocking cap's are shown on the schematic as being rated for 60V, so that's a good sign. Motivated individuals might be interested in adding a 48V phantom supply internal to the G2.

[KC2QMA]

Thanks for the info Scott!

OK TRS balanced input is 20k ohms.
Looks like the input is high gain and will take quite a bit of input.
I wonder how much audio input it takes to just start to activate ALC in the PA (Unity Gain)?

For the FAN I guess it's a standard 2 wire 120mm 12vdc pc case fan. Would like to know what the specs for the stock fan is,
What is the max current allowed for the FAN in the G2?

[qst]

There is no high resolution image of the G2 on the Apache-Labs website. The front plate has a cutout on its upper edge. Is there a housing latch and an LED there? I'm waiting for the G2 to be delivered and I'm curious what's installed there.
Slawomir

[KI4P]

There is no high resolution image of the G2 on the Apache-Labs website. The front plate has a cutout on its upper edge. Is there a housing latch and an LED there? I'm waiting for the G2 to be delivered and I'm curious what's installed there.
Slawomir

the cutout you see is there for a tab on the top to fit in, see attached

IMG_0935.JPG (1.3 MiB) Viewed 5708 times

Richard

[gw0hyu]

Hi all,

Can anybody confirm that that G2 has the TLV320AIC3204 codec implemented , and where on the PCB, and whether there is a direct jump point to pick up the line in pins e.g 13,14,15,16 . I cant seem to find any G2 circuit diagrams available. Looking at the physical board maybe J56 facilitates a direct line input to the codec as this seems to be where the output of the TRS differential microphone opamp amp is terminated , coul dbe off course here but without diags its surmising :0)

Just to highlight similar observations of other owners, my G2 has RFI on the TRS input, which is internally generated even at just a few watts of output - a single clip on ferrite (provided on mine) will afford just a few 10s of Ohms of choking impeadance at best at HF which is of course not the answer.

Any hoo I'm TX audio configured using WASPI drivers via ethernet and VAC audio is nothing short of stella - ultra prstine and clean, zero RF negligable latency and no dropouts. Dont think CMASIO will improve on it... will have a try though....

[laurencebarker]

The codec is a TLV320AIC23B. We know that it will need to be replaced eventually but there is no short term need. Its line inputs are tracked directly to the Line in 3.5mm connector on the rear panel.

The differential preamp is on a separate small board, and feeds into the codec microphone input via J56. There are notes on a another thread about how I modified that to eliminate TX interference.

[gw0hyu]

This is based on the circuit design being comprised of an NE5534 op amp in differential, non-inverting, single supply configuration and having a gain of 10. This is followed by a TLV320AIC3204 CODEC chip. This is significantly different than the TLV320AIC23B used in previous ANAN designs. The 3204 is in a configuration that allows a maximum, single-ended 0.9V audio input.
.

So some confusion here, it seems that the Codec on the new G2 is not the TLV320AIC3204 but the same Codec implemented on the Anan 7000 TLV320AIC23B which is obsolete ?

Cheers
Keith

[gw0hyu]

The codec is a TLV320AIC23B. We know that it will need to be replaced eventually but there is no short term need. Its line inputs are tracked directly to the Line in 3.5mm connector on the rear panel.

The differential preamp is on a separate small board, and feeds into the codec microphone input via J56. There are notes on a another thread about how I modified that to eliminate TX interference.

Super thanks for clarifiying Lawrence. I dont think human ears will discern the tiny differences in audio quality between the 2 Codecs. Indeed my 7000 DLE MK2 and G2 surpass the TX quality of any other SDR s Ive owned to date (and Kenwood TS950SDX), using ethernet and ASIO / WASPI drivers in VAC , in my humble opinion.

Ive likley mis-spent many hundreds of hours proving so to myself , having owned the FTDX's, SUN SDR, Flex and ELAD radios recently )

[rdwing]

Hi all,

Can anybody confirm that that G2 has the TLV320AIC3204 codec implemented , and where on the PCB, and whether there is a direct jump point to pick up the line in pins e.g 13,14,15,16 . I cant seem to find any G2 circuit diagrams available. Looking at the physical board maybe J56 facilitates a direct line input to the codec as this seems to be where the output of the TRS differential microphone opamp amp is terminated , coul dbe off course here but without diags its surmising :0)

Just to highlight similar observations of other owners, my G2 has RFI on the TRS input, which is internally generated even at just a few watts of output - a single clip on ferrite (provided on mine) will afford just a few 10s of Ohms of choking impeadance at best at HF which is of course not the answer.

Any hoo I'm TX audio configured using WASPI drivers via ethernet and VAC audio is nothing short of stella - ultra prstine and clean, zero RF negligable latency and no dropouts. Dont think CMASIO will improve on it... will have a try though....

Wasapi is great, doubt you'll see much if any improvement with cmASIO, at least we didn't here.