[NLRS] Test Plan for HT Transmit Quality up to 1300 MHz?

[Thomas Murphy]

The tables of stuff from Hanger 18 Surplus at Central States this year 
managed to get me moving on the path for both options. I purchased the 
following:

  * Weinschel WA24-30 power attenuator
  * Alan 50SP10-N low power attenuator
  * HP8493A 10dB signal attenuator
  * Microlab/FXR HZ-A17 adjustable capacitive sampler
  * EMCO T350M SMA power termination

Acquiring the 2 GHz 40 dB resistive sampler from China is still an 
option, but I'll have enough testing and evaluation to chew on to start 
with. Certainly checking out the coupling slope of the HZ-A17 (not a 
standard part number!) will be an interesting experiment. Fortunately 
the specan I'll be using includes the tracking generator!

I also found that there's an Obsolete series of resistive samplers that 
Microlab/FXR made two decades ago, the HM (HM-10N through HM-30N) that 
has a little information in an archived datasheet I dug up. Of course 
they're not really available on the surplus market by name right now. 
Thoroughly power limited by the internal coupling resistor choices, but 
one of them did come up as being used in a test setup for some FCC Part 
87 equipment in web searching.

- Thomas / WN1C


On 5/26/24 19:55, Thomas Murphy wrote:
> Seeking VHF+ wisdom as alluded in the UV-K5 discussion: what does the 
> test setup look like for HTs (and throw in transverters up to 10W) 
> through 1300 MHz when working with a signal-level input spectrum 
> analyzer? My concerns are second/third harmonics, then fundamental 
> output power, then modulation quality. If you have your own setup to 
> reference, that would be handy!
>
> For background, I have access to a 7.5 GHz Tek USB spectrum analyzer 
> at work (https://www.tek.com/en/products/spectrum-analyzers/rsa600) 
> that, of course, will only work with a direct connection to your 
> antenna port for your basic IoT sort of devices (+30 dBm > 10 MHz). I 
> haven't figured where the best dynamic range for harmonic testing on 
> this instrument is, but I'm hoping its flexible input attenuator helps 
> keep that decent. I could probably check flatness with the unit's 
> tracking generator, then see about loading correction factors.
>
> The two techniques I've figured for appropriate sampling are external 
> direct attenuation (power attenuator) and wideband RF sampler 
> (non-directional) with external power termination on the through port. 
> Of course, this being amateur and for my hacking project, I'm hoping 
> to keep the additional equipment economical rather than laboratory 
> grade (unless there's a deal on the right part!).
>
> On the sampler side, there's either Bird or RF Industry variable 
> samplers, then this one commercial non-directional sampler I can find: 
> https://www.ebay.com/itm/NEW-DC-2GHz-40dB-ultra-wideband-RF-sampler-SMA-interface-/283235697566 
> . Add a load and a bit more sampler attenuation to set the level.
>
> I could also just go with a 10 W, 3 GHz, 30 dB attenuator (plus maybe 
> pad that with one of my 1 W class signal attenuators from my nanoVNA 
> kit). There are some nicer rated (12 or 18 GHz), manufacturer branded 
> models out on eBay for maybe decent rates as used models.
>
> Possibly overthinking it; looking forward to your input.
>
> - Thomas / WN1C
>
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