Rx wider frequency range

VK3KYY
Posts: 3006
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia
Contact:

Rx wider frequency range

Post by VK3KYY » Sat Apr 18, 2020 1:46 am

Someone commented to me, a while ago, that the using the official firmware they were able to receive on a wider range of frequencies than allowed by the OpenGD77.
I did some tests with several of my GD-77s, and it looks like the Rx frequency range can be extended, beyond the published specification of the baseband RF chip (AT1846S)

My radio seems to be able to receive (and also to transmit into a dummy load) on these ranges of frequencies

128Mhz - 177Mhz (Datasheet values are 134Mhz - 174Mhz)
190Mhz - 280Mhz (Datasheet values are 200Mhz - 260Mhz)
380Mhz - 560Mhz (Datasheet values are 400Mhz - 520Mhz)

Some of my GD-77 will go slightly beyond those limits, but not all of them will, so I think that the PLL is not locking on all my radios if I go beyond this range.

I'd be interested to know if everyone's radios seems to operate over this range, or whether I need to reduced it a little to guarantee that its OK for 99% of users.

I've also made a change to the code, so that the UHF Rx and UHF PA is used for all bands except for the VHF, as this gives results when listening below 400Mhz, but above 177Mhz

I also did another failed experiment of setting the baseband clock input setting to 13Mhz, even though its being supplied with 26Mhz from the master reference oscillator, in the hope I could receive above 560Mhz by specifying half the frequency but using twice the clock frequency.
e.g. 380Mhz x 2 = 760Mhz. But the PLL didn't seem to lock at all if I did this.

So I think this is the maximum frequency range which can be achieved.

The range limits I've put in the firmware are

127MHz - 178MHz
190MHz - 282MHz
380MHz - 564MHz
Attachments
OpenRD5R.sgl
(481.12 KiB) Downloaded 76 times
OpenGD77S_HS.sgl
(477.08 KiB) Downloaded 64 times
OpenDM1801.sgl
(481.11 KiB) Downloaded 80 times
OpenGD77.sgl
(477.06 KiB) Downloaded 176 times

User avatar
IU4LEG
Posts: 172
Joined: Wed Nov 20, 2019 12:49 pm

Re: Rx wider frequency range

Post by IU4LEG » Sat Apr 18, 2020 2:30 pm

hi all, my gd77 frequency range work:

127Mhz - 178 Mhz

190 Mhz - 282 Mhz

380 Mhz - 564 Mhz

TNX, IU4LEG

User avatar
IU4LEG
Posts: 172
Joined: Wed Nov 20, 2019 12:49 pm

Re: Rx wider frequency range

Post by IU4LEG » Sat Apr 18, 2020 2:34 pm

It was also implemented the microphone gain for the FM?

User avatar
F1RMB
Posts: 825
Joined: Sat Nov 16, 2019 5:42 am
Location: Grenoble, France
Contact:

Re: Rx wider frequency range

Post by F1RMB » Sat Apr 18, 2020 2:54 pm

IU4LEG wrote:
Sat Apr 18, 2020 2:34 pm
It was also implemented the microphone gain for the FM?
Yes.

Cheers.
---
Daniel
73 de Daniel.

LY1RF
Posts: 25
Joined: Sun Mar 01, 2020 12:05 pm

Re: Rx wider frequency range

Post by LY1RF » Sat Apr 18, 2020 3:45 pm

two dm-1801

127.000 - 178.000
190.500 - 279.500
381.000 - 559.000

R.

User avatar
W1AEX
Posts: 110
Joined: Sat Nov 16, 2019 9:00 pm
Location: Connecticut, USA
Contact:

Re: Rx wider frequency range

Post by W1AEX » Sat Apr 18, 2020 4:09 pm

I really like this release. I found that by setting the FM MIC level to 3 the GD77 matched the FM transmit audio level of my CS-800D which gets very good reports on FM. Both of my GD77's were noticeably anemic with their default FM transmit level setting of 1.

My newer GD77 (DEC 2019) and my older GD77 (JUL 2018) can successfully run from:

127-178
190-282
380-564

Programming outside of those ranges results in the unhappy beep tone but pressing the red key puts you right back to the last successfully programmed search range.

Thanks very much for this release!

73, Rob W1AEX

G0NHF
Posts: 61
Joined: Sun Jan 19, 2020 10:28 am

Re: Rx wider frequency range

Post by G0NHF » Sat Apr 18, 2020 5:12 pm

Working fine. 5x GD77

127Mhz - 178 Mhz
190 Mhz - 282 Mhz
380 Mhz - 564 Mhz

Regards
Tony

User avatar
f6fzo
Posts: 47
Joined: Sat Jan 04, 2020 7:28 am

Re: Rx wider frequency range

Post by f6fzo » Sat Apr 18, 2020 6:04 pm

Merci :D
F6FZO Serge 43 Nord

F6GVE
Posts: 76
Joined: Sat Nov 16, 2019 8:52 am

Re: Rx wider frequency range

Post by F6GVE » Sat Apr 18, 2020 8:40 pm

Hi :)

Only tested in TX at the moment

GD77 no1
127-178
190-277 (277.5 but not always)
380-555 (555.5 but not always)

GD77 no2
127.7-178
191.4-282
382.8-564

GD77 no3
127-178
190-279.5
380-559

EB3EEL
Posts: 37
Joined: Wed Mar 11, 2020 6:35 am

Re: Rx wider frequency range

Post by EB3EEL » Sat Apr 18, 2020 9:10 pm

RX and TX in:
127.000 - 178.000
190.500 - 282.000
381.000 - 559.000
in my 2 GD77 with no problem, have to measure the tx power and rx sensibility in another moment.
Thanks
MR
Miquel EB3EEL 2143638 Barcelona, Catalunya, Spain

Post Reply