1. VNA comes with SMA and QMX with BNC. So you use at least one additional adapter. Could you tell how the antenna cable is connected in each case?
2. BNC connectors are reliable. But in rare cases contacts maybe out of shape producing bad connections.
3. I'm not sure about the frequency accuracy of the used VNA. Afaik you could use a VNA as a generator for single frequencies. So you may set the VNA on a frequency in the 20 m band and receive with your QMX. Is there a difference? Please don't connect both! Put each device away from the other. Don't connect an antenna to the QMX. An open BNC should be ok.
4. You should really look for a dummy load.

73, Ludwig

As outlined that is the way to go.

You may consider a low level PTT control for that so the keying voltages
for the amp and driver are compatible. also a way to shut down the
driver amp for a mid power solution.

--
Allison
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Post online only,?
direct email will go to a bit bucket.

Hi

I'm reaching out to the experts for advice, guidance & help please.

The Hermes Lite 2, "HL2", is a DDC/DUC SDR transceiver - - which can output upto 5W PEP RF.

The RM Italy BLA-350 plus, "Linear", is a 400W PEP HF Linear amplifier - with an input drive of upto 10W.

At 5W RF out from the HL2, the BLA-350 puts out about 130W PEP.

So, the problem is how to get the output of the HL2 from 5W to 10W to drive the BLA-350 ?

The solution looks like it might be to use the QRP Labs 10W Linear Amplifier - - “PA”, to generate the 10W required to drive the BLA-350 to full power output.

The first step is to reduce the 5W HL2 output down to 25mW acceptable to the PA, a T attenuator giving about 25~26dB attenuation should reduce 5W to around 25mW. The T attenuator would comprise of 2 x 45 R in series with a tap to ground of 5.6R to yield an attenuation factor of -25.11dB - . The HL2 does have a 17dBm fixed output intended for transverter operations but one would still need to arrange for receive signal switching; the approach I've taken I think permits me to use the drive level in the HL2 to control the output power from the Linear.

During receive, the PA, and attenuator must be bypassed; during transmit, the receive chain needs to be bypassed, relays are used to carry out the required switching operation when PTT is closed /connected to ground by the HL2.

Hopefully the schematic below describes what I think needs doing with sufficient clarity.

I would really appreciate your advice, guidance, help, suggestions for improvements, and of course correct my errors.

Very Many Thanks, 73

Peter - GM8JCF

Hi Francesco,

The green ”COLOUD" speaker that Steve links to is decent and very lightweight. It doesn't have great battery life though, at least my one doesn't.?

The Anker Souncore mini is also decent but it's fairly weighty for its size. Sound-wise, it's a great match for these little radios although theres a very slight latency, even on line input, which could be an issue if you're a speed-machine on the key....

For something really small and lightweight, try one of these (link below). I use it for SOTA etc and it's incredibly small, lightweight and LOUD. It has impressive battery life too. The only downside is that you need a small 3.5mm extension cable due to the location of the audio socket on the QCX/QMX radios. This specific model is no longer in stock but there are many others exactly the same if you look about... Here's the link:

Leadsound Portable Speaker:?


Cheers,
Ronan
MM0IVR?

No problems with a straight key on any of my QCX's. The only time I had a issue was when using a particular amplified Bluetooth speaker. Even though I was plugged into the line input, there was a discernable latency.

I wonder if that's the cause of the OP's issue. A simple check with normal (not Bluetooth etc) headphones plugged directly into the audio out jack should reveal if it is.?

Cheers,?
Ronan
MM0IVR?

I haven't heard of this issue before, but I have experience different audio anomalies with different headphones.? Sometimes it's just the impedance of the headphones, or the connector. I have trouble with those ones that have the four rings. I also had a problem with a pair of Sennheisers that had super long cables. They picked up all kinds of RF and were almost impossible to use.

--
73, Dan - W2DLC

On Fri, Jul 12, 2024 at 06:16 PM, Dave VE3GSO wrote:

Return Loss

Thank you for your suggestion.

So I followed these 2 videos

I calibrated my VNA and set the following parameters:
Freg Range - Start: 13.8Mhz
?????????????????? - End: 14.5 Mhz?

I set 2 markers. One at 14.024 and another at 14.075 750

As you can see from the picture I have a very low SWR. I believe that I also have a Return Loss of -26.77dB at 14.024 MHz and -20.76dB at 14.074 MHz which I think is within the acceptable limits.



I unplugged the antenna from the VNA and plugged it straight into the QMX and as you can see when I run the Hardware Test SWR Sweep I get nearly 5.0 on the 14.074 MHz frequency.



Am I doing something wrong?

Typical pot setting as the IRF transistors start to conduct (yours may vary, increase very slowly )?

I also take from this single poster, that no one else has had this experience? If so I can get around it by using a paddle, I can also try using a bug.

I've now sorted the power problem on 6m. It appears that the inductors L519 & L520 are super sensitive to turns spacing, tweaking those improved the O/P power, but the main improvement came when I removed a turn from both coils. I now have over 3W on all bands...

Hope this will help anybody else with a similar problem.

73 Dave G4FAW

I'll make a video later when I get time.

Is it possible that is the sidetone sounding a little soft?? Maybe you could record a little of the sound and post it so we could get a better idea.
--
73, Dan - W2DLC

Thanks for your explanation.
I'll buy you another coffee - hope you can get an iced coffee during the summer.
Chris

I am also a fan of the 1050 case.

Additionally, I have this 3D printed cover ( Thingiverse)? to protect the screen and controls.? That is severs as a stand is quite the bonus.

开云体育

If this were me I would first completely calibrate the VNA for a bandwidth of 13.8 MHz to 14.5Mhz to zoom in on the 20m band, so that you can accurately read the Return Loss across this narrow frequency band. A good reading is below -20dB and -25dB is better.

I like this Anker speaker too.
Battery lasts very well, sounds good with QMX.
Also sounds good with music, with good Bluetooth range.

I just wonder why the peaks of the sine waves are flattened.? Is this a hardware or software saturation?