Yes; that’s what I did in the Yaesu 750 thread. I am using a laptop driving a USB sound card, which drives the modulation input of a Marconi RF signal generator which produces the carrier. This guy is just using a different signal generator from mine.
If you are saying that generating both the LOC and the GS at the same time is not hard, I agree 
But you need two RF transmitter channels – one for LOC and one for GS. That is almost 2x the number of bits. The guy in the video skips over that bit in about 2 seconds, but with his single sig gen he can still do only one at a time.
However I think with an IFR4000 being ubiquitous among the better avionics people, the market for a cheap ($1k) box is a bit limited. It gives you only functional testing. It won’t pick up a break in a cable or in an antenna unless the break is total. To pick up those problems you need an attenuator on the two RF signals, and while that is today technically ok, it is not exactly cheap to do.
Peter wrote:
But you need two RF transmitter channels
Many SDR transceivers do – the LimeSDR for example has two independent full duplex RF out/in channels which will go from 100 kHz to 3.8 GHz (and up to 60 MHz bandwidth on each channel).
http://www.sunavionics.com/AV15_Specifications.html
If someone was using it? Any feedback?
@Przemek post moved to existing thread.
I looked at developing exactly this a few years ago, but decided there would not be enough business.
One limitation of these cheap ones is that for testing electronic HSI systems you need to emit both LOC and GS concurrently.
I am still looking for a secondhand IFR4000.
How much is for ifr4000 used?
My contact in the US avionics business tells me he hasn’t seen one recently for under $10k.
If it’s just the Nav/Com parts you want (an IFR 4000 also does ELT) then a used NAV401L is much better value than a 4000. It will generate simultaneous LOC and GS for testing autopilot coupled approach. The 401L has some com capability – you can generate a test transmission and do receiver sensitivity and also measure aircraft transmit power and frequency.
The Sun box does work well – I know a couple of guys in the UK who use them and they seem very capable for the price. They can do the full ADS-B output test including SIL and SDA values which my more upmarket TR220 won’t.
I have a Sun box and it is a tremendously useful gizmo; as to generating both LOC and GS, it looks like buying two Sun boxes still gives a good value for money
Ye, 10k its too much for me. 2-3k eur would be ok. If case of G5 – if I will generate GS w/o LOC it will display it? It’s most common hsi at my garage, don’t need much more for this option.
Ultranomad wrote:
I have a Sun box and it is a tremendously useful gizmo; as to generating both LOC and GS, it looks like buying two Sun boxes still gives a good value for money
How are you happy with quality of unit?
