6 meter band receivable ?

✔ Now supported, kit available by the end of September 2020.
User avatar
sm6fhz
Posts: 179
Joined: Wed Aug 19, 2020 3:21 pm
Location: JO57XJ
Contact:

Re: 6 meter band receivable ?

#11

Unread post by sm6fhz »

Hi Paul.
I am also interested in 50 MHz coverage in the RX-888Mk2 using SDRC.
Have you actually used one RX-888Mk2 for receiving 50 MHz?
Have you evaluated the performance in any way (e.g. noise floor, sensitivity, NF etc.)?
How did you set up the SDRC in order to receive 50 MHz?
Presently I have a plain RX-888 but have had thoughts about getting a Mk2 unit as well. Just for 50 MHz coverage.
73 / Ingolf, SM6FHZ

User avatar
sm6fhz
Posts: 179
Joined: Wed Aug 19, 2020 3:21 pm
Location: JO57XJ
Contact:

Re: 6 meter band receivable ?

#12

Unread post by sm6fhz »

Paul.
If your RX-888Mk2 does receive 50 MHz, is that on the "H" or "V" port?
My plain RX-888 does receive 50 MHz on the "V" port but with reduced performance.
73 / Ingolf, SM6FHZ

N8CVW
Posts: 28
Joined: Sat Jan 02, 2021 7:28 pm

Re: 6 meter band receivable ?

#13

Unread post by N8CVW »

Hi Ingolf

I’ve not made any measurements yet but planning to soon.

I simply ran a quick receive test around 52 MHz with an FM audio/voice transmission radiated from an FT817 .

RX888Mk2 connected to antenna on the H port.

Spectrum looked like normal FM, sounded fine, signal strength normal for the proximity.

I expect to have some additional results this weekend.

best,

Paul
N8CVW

User avatar
sm6fhz
Posts: 179
Joined: Wed Aug 19, 2020 3:21 pm
Location: JO57XJ
Contact:

Re: 6 meter band receivable ?

#14

Unread post by sm6fhz »

OK Paul.
SDRC (latest kit) directs my RX-888 to the "V" port when setting the receive frequency >32 MHz. I.E. it is not possible to receive 50 MHz on the "H" port on my unit.
That is why I am interested in knowing how you receive 50 MHz.
Maybe someone knows if SDRC acts differently for the plain and the Mk2.
My understanding has been that Simon has not done anything to SDRC to distinguish between them so far. Hopefully I have got it all wrong :-)
73 / Ingolf, SM6FHZ

N8CVW
Posts: 28
Joined: Sat Jan 02, 2021 7:28 pm

Re: 6 meter band receivable ?

#15

Unread post by N8CVW »

Good morning Ingolf

I was just reconfirming the operation on 6mtrs.

Yes, I’m on H port. I tested both 2 & 4 MHz bandwidth operation. 4MHz covers 50-54 and same clear signal + audio. Responds just like any other band.

As soon as I can I will check sensitivity as against the Sencore SA1454 signal analyzer, the closest thing I have to a calibrated receiver. The specs say 0.1 dB accuracy but I think there might be a few 1/10s more uncertainty, will look more closely .

I don’t know anything about the Mk2 vs non-Mk2 SDRC implementation, nor do I know what the radio differences are, if any with respect to 6M reception.

I’ll be back !

Paul
N8CVW

Max
Posts: 859
Joined: Thu Aug 13, 2020 9:47 am

Re: 6 meter band receivable ?

#16

Unread post by Max »

sm6fhz wrote: Fri Dec 03, 2021 1:16 pm OK Paul.
SDRC (latest kit) directs my RX-888 to the "V" port when setting the receive frequency >32 MHz. I.E. it is not possible to receive 50 MHz on the "H" port on my unit.
That is why I am interested in knowing how you receive 50 MHz.
Maybe someone knows if SDRC acts differently for the plain and the Mk2.
My understanding has been that Simon has not done anything to SDRC to distinguish between them so far. Hopefully I have got it all wrong :-)
73 / Ingolf, SM6FHZ
Hi Ingolf

I don't have the RX888 (any flavour) but my gut says that SDRC simply tells the radio on what frequency to receive and how it is switched internally is in the hands of the firmware of the RX888, i.e. if it (Mk2) is told to receive on any frequency up to 64MHz it uses the H port (direct sampling) and anything above that it switches to the V port. I would think this is transparent to SDRC?

The spec says direct sampling to 64MHz and anything above that uses the VHF/UHF tuner via Port V at a maximum of 10MHz bandwidth.

I suspect that when SDRC drives your 888 Mk1 there is nothing in SDRC to select one port or the other? It just happens automatically surely?

That's how I interpret it anyway, FWIW.

73

Max

User avatar
ukdx
Posts: 41
Joined: Wed Nov 18, 2020 7:52 am

Re: 6 meter band receivable ?

#17

Unread post by ukdx »

How did you achieve that in Console Paul, I've got SDRC 3.1 but I can only see up to 32MHz bandwidth and even that rolls off above 30MHz. No matter what settings I try 50MHz is on the VHF port as evidenced by the 10MHz wide raised noise floor.

Most of my listening is between 24 and 70MHz so I still have to use Sharp with the extio sampling at 140MHz, it produces a bandwidth of just over 63MHz anywhere between 0 and 70MHz with narrow slices of 2, 4, 9, 18, 35 and 70MHz available.

I uploaded this yesterday to demonstrate to someone else the available bandwidth so I'll share it here.

I can't fault it for the price, I compared it to my Elad S3 on HF and yes the S3 was more sensitive to weak signals but given the 888 has to run at max gain it made me wonder if a small wideband preamp would compensate. The difference however is very small and it took quite a bit of listening to be sure, if I was in to general HF listening the 888MK2 would be more than sufficient and a fraction of the cost.

Someone asked about purchasing one and who to trust, this is the seller that Justin linked too from his Twitter account if that counts for anything.
https://www.aliexpress.com/item/1005002133979911.html

N8CVW
Posts: 28
Joined: Sat Jan 02, 2021 7:28 pm

Re: 6 meter band receivable ?

#18

Unread post by N8CVW »

Hi UK’

I’m doing nothing special, it just works as hoped for.

I have a 2nd RX888Mk2 from a different supplier, they both look alike. It functions just like the 1st one.

Still getting around to calibrating the gain to the calibrated receiver.

Off the cuff, I can say these are less sensitive and noisier than the Airspy R2 on the 162.55 weather broadcast. (no external preamp)

I’ll be optimizing for each receiver, correlating S-meters, etc, then hope to have a more clear comparison.

Paul
N8CVW

N8CVW
Posts: 28
Joined: Sat Jan 02, 2021 7:28 pm

Re: 6 meter band receivable ?

#19

Unread post by N8CVW »

Hey Everyone

I found the 'red herring' ...

I noticed that when the radio is set in the 6 meter range, the VHF controls are active, and drop down to 10 meters and the HF controls are active (VHF controls deactivated).

And, the 53.100 MHz signal is received regardless which port H/V the antenna is connected to. There may be some level difference, not sure, may be due to different gain settings when switching around, but operates seemingly the same.

SO, no direct sampling on 6 meters as yet.

Paul
N8CVW

User avatar
sm6fhz
Posts: 179
Joined: Wed Aug 19, 2020 3:21 pm
Location: JO57XJ
Contact:

Re: 6 meter band receivable ?

#20

Unread post by sm6fhz »

Paul, that is exactly the way my plain RX-888 works.
VHF controls kicks in at frequencies >32 MHz.
73 / Ingolf, SM6FHZ

Post Reply