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LNR LD-5 rig review


#22

All,

Maybe these artifacts are due to a hum loop in the audio connections used for the tests.

73
KX0R


#23

Thanks Ignacio for hard work. Is it possible, that you switch off the dsp IF, when measuring ? It is easy to do , unintentionally. The radio operates perfectly with 100Hz filter bandwidth , as you see the narrowest filter shows those so called spikes. I have checked mine and i does not have any spikes , even at 60Hz filtering. Also, i miss understood the comment about impedance protection, isn’t it worth exactly to be effective between 35 to 100 ohms ? Radio has a digi mode , where all known software have being tested and working perfect. Any logging software as i.e. N1MM, dx log etc. sets CAT system easy.


#24

Hello,
Thanks so much for your input Nick. It is a pleasure counting with the expertise of one of the creators of this nice rig!

I did some more tests and I think I have a better view now

  • Spikes.

Just to make sure about them I did one more test.
This time I switched on the rig battery powered, without any antenna, and plugged my studio headphones. I decreased the volume completely and, there you were!, I could clearly hear a low buzz electric noise. I think this is the real reason for these spikes.

No matter the band, neither the mode (I cycled between LSB / CW / Digi…) nor the Filter level (1 to 4), that buzz noise was there the same way all the time. Could it be it is not a Filter issue but maybe something defective in my specimen (Serial number 0202) in the audio stage perhaps?

I measured again the spectrum to check the floor noise (radio off) then the spikes with zero volume , and again the spikes when receiving at medium volume level:
(Spectrum from 0 - 1000 Hz shown)

Maybe the rig you have doesn’t have this issue and it is only present in my part? Just check yours with headphones and zero volume and see if you can hear the buzz noise…

I am sure that if I hadn’t plot the audio spectrum I would never have noticed about the spikes because it level is low. For sure, when you use the rig, the breeze on the countryside or even operating at home you will never tell about them, so the receiver works fine for me.

  • Impedance protection

I do find there is room for improvement there. I don’t have any issue when working with a proper 50 ohm antenna but if I use a simple antenna in the countryside and switch between CW section and SSB section in a band, I can expect a SWR variation. Moreover, when working with a simple piece of wire even if it is a resonant antenna as it is the case for me.

The problem here is the excessive reduction you will get from the rig because it reads a too high value when it is not the real value present in the antenna (i.e., the rig reads 7:1 SWR and reduces power to 1,5 watt output while it is 4:1 SWR present in reality).

I agree that if you have a proper antenna with a decent bandwidth you won’t have any problem with this rig and the LD-5 probed to be effective in the default 50 ohm range.
The point is that if I have a value indicated on the Display, I would rather prefer to have a proper measurement. Is it something you could improve on a firmware update, maybe?

  • Digi modes

I am not fan of them and have not testesd on my specimen. Probably they will work fine with a proper setup.

Again, thanks Nick for your words, and I keep saying it is a very valuable little rig which works fine for me, even having these minor bugs. I just opened the door for some improvements that would increase even more its value in the market.

73 de Ignacio

P.s: I didn’t mention in my review it is possible to get the 11 band version of this rig here in Europe, called Sky-Sdr.


#25

“The receiver draws about 350 miliamps with a normal volume level, all filters disabled and the display backlight on.”

I don’t now what R&D people do? Do they think about portable use?
Rx current consupsion is 10x too big. It is possible to construct Rx with such characteristics with current consupsuion about 30mA…
For example, my HM RIG 3om30 has 20mA Rx current, and toghether with separate DDS VFO about 30mA.

73 from Alex


#26

Hi Alex,

yes, it could be better but this is not the only rig with such current drain on receive.
Even the popular FT-817 has a bit more than 400 milliamps and it is still used widely here by SOTA operators or any other fan on portable activation.

Elecraft is doing much better on the KX’s family reducing to levels around 150 miliamp.

I have seen lower current drain values when speaking about CW only rigs (MTR, etc), but if we look at a CW + SSB rigs it is difficult to get to that low level.

I wish LD-5 had a better figure but this is it nowawadays. Due to the fact I moved from an FT-817 to this LD-5 I have improved a bit, and I’m used to such consumption level.

73 de Ignacio


#27

So shouldn’t there be “spikes” on every filter setting? I thought the spikes were only present on the narrowest filter setting.

73, Barry N1EU


#28

Indeed Barry!
The spikes were present on every filter setting.
And according to my last post, the spikes are not related to the filter. That buzz noise is present all the time no matter on CW or SSB, and is probably an issue in the audiio amplifier stage.

Anyway, we spend lots of messages here to speak about such spikes but, as I told, they are not relevant and I can operate with very good feeling in my ears.

As suggested, as long as there was no input from a second user of an LD-5 I couldn’t tell whether it happens only in my sample.

73 de Ignacio


#29

Hi Ignacio,

Now i understood !

DSP is not linear and analog unit. In order to operate, you have to activate it. When RF signal is missing on the input , DSP is not operational at all!! Please , apply whatever signal to the antenna input , even several microvolts , and you will see the difference ! Sorry, that it was misunderstanding between us . It is my fault , i tought you know about DSP functionality.
My best wishes for last test you going to provide, hopefully without attenuation. One more small request, you can replace sig. generator with real antenna during experiment - i.e. dipole on a closed band -80m day time…

73 Nick