Pages: [1]   Go Down

Author Topic: Direct conversion receive  (Read 402 times)

KD0LQD

  • Posts: 3
    • HomeURL
Direct conversion receive
« on: May 21, 2022, 06:53:39 AM »

It’s my understanding that a superheterodyne is far more selective than a direct conversion radio.  With that in mind I’m confused on why the new icom ic-t10 is demanding a $240ish price tag.  Am I missing something?  I don’t want to bash a brand but… someone help me out here.
Logged

N7EKU

  • Member
  • Posts: 1471
Re: Direct conversion receive
« Reply #1 on: May 21, 2022, 01:10:10 PM »

Hi,

I don't think you can make an assumption like that since it depends on so many things.  Maybe check this out:  https://www.onallbands.com/superheterodyne-sdr-hybrid-sdr-which-is-best%EF%BB%BF/

73
Logged
Mark -- N7EKU/VE3

KD0LQD

  • Posts: 3
    • HomeURL
Re: Direct conversion receive
« Reply #2 on: May 21, 2022, 02:32:57 PM »

Thanks!



Hi,

I don't think you can make an assumption like that since it depends on so many things.  Maybe check this out:  https://www.onallbands.com/superheterodyne-sdr-hybrid-sdr-which-is-best%EF%BB%BF/

73
Logged

KM3F

  • Member
  • Posts: 1103
Re: Direct conversion receive
« Reply #3 on: May 21, 2022, 03:04:57 PM »

I now have some observation experience between the two detection systems.
On an HT with direct conversion, the sensitivity is very high on the unit I have at .1 uv according to specs for the unit. That' well up there with the best.
Observations:
It hears a lot of power line leakage, a lot of trash being from other sources, and systems as I drive around in mobile.
In my area it can sense high powers above the 2m band in business and mobile phone and paging systems.
Case in point; F =152.720. High power was overloading the HT.
To solve the issue, I built a trap for that frequency to the tune of more than -55dB down and solved the problem. The trap was tuned on a VNA then installed in series with the HT to antenna.
.
The two take aways are the sensitivity and the single conversion.
Both are very good with the absence of interference but can be a problem in that presence.
It seems that more selectivity can be accomplished after the IF is converter to with more filtering but is a function of the radio application, design and what can be tolerated in operation.
I'm not condemning single conversion but understanding what disadvantages there may be in certain circumstances.
I use an HT and small 35 watt Linear amplifier as a mobile radio and love the operation otherwise.
Radio hears better than it gets out for mobile; the Tx audio is first class with a hand mic.
.
In an HF radio, I would expect more filtering before and after the mixer and the best mixer design to eliminate harmonic mixing results my HT does not have in a small package and price point.
I was lucky to get away with the HT so easy.
The out of band interference is from stations that are allowed to run a lot of power if needed for their service.
Not good for 2m in some areas when you live close by.
« Last Edit: May 21, 2022, 03:11:35 PM by KM3F »
Logged

WA3SKN

  • Member
  • Posts: 8126
Re: Direct conversion receive
« Reply #4 on: May 21, 2022, 04:58:59 PM »

The reason for the cost is the MIL specs and weatherproofing... not receiver selectivity.

-Mike.
Logged

AF5CC

  • Posts: 1664
    • HomeURL
Re: Direct conversion receive
« Reply #5 on: May 21, 2022, 10:48:08 PM »

The Alinco DJ-VX50 has almost the exact same specs, including the IP67 rating, for $90.

73 John AF5CC
Logged

KD0LQD

  • Posts: 3
    • HomeURL
Re: Direct conversion receive
« Reply #6 on: May 22, 2022, 05:37:50 AM »

It will be good to get my hands on an IC-T10 to get it apart and check it out.  I would love to compare a DJ-VX50 to it too.
Logged
Pages: [1]   Go Up