The best time to catch some 70cm DATV activity is on one of the BATC activity weekends. Be very careful not to overdrive these modules or you will destroy the input stage. I always use a variable attenuator to slowly drive them up. For DATV use, you need very linear class A operation, which is not how commercial amps are usually set up. On class A operation, the quiescent current is not much less than that at full power so they are often only 25% efficient.
defo get a spectrum view of that Mitsi chip output - that package is notorious for harmonics, and i suspect your power reading will take a dive when you LPF it.. Maybe it's different on the 400Mhz variant, but the low-band VHF one (good for 4m) is a stinker for harmonics.. just FYI
The only filtering on this is done by the internal matching of that amplifier monoblock, it's definetelly not recommended to run it at full power with something like an SDR without other filtering, bandpass, not a lowpass.
You probably won't get anywhere near the power output of your handheld's NFM signal with the bandwidth of a DATV signal for the sake of linearity. Also it would be good to know the class of operation. If it won't work on SSB you likely can't use it for DATV.
There is no delay or PTT control, so SSB would be no no. However, Im not sure what you mean regarding "if it wont work on ssb you likely cannot use it for datv". I have built 2.4GHz amplifiers that used certain pallets which did NOT work on SSB but worked amazing on DATV. It will be interesting to see the power output once I use a 333k/s DATV signal on the input! :-) One can only try and cross fingers and legs lol.. Cheers
@@TechMindsOfficial I did not think an OFDM type signal would work properly with say a class C type amplifier. I'm thinking that amplifier is mostly meant for FM handhelds. If you have different experience it will be interesting to see.
I think you are right concerning it's original design, it's meant for handheld. There is a website online, Enigma web shop which sells these modules and a separate PCB which looks really interesting as it supports PTT. If you do not see a video of me using DATV with this amplifier in the next few week, you will know it didn't work! lol. Cheers mate.
@@TechMindsOfficial Looking at the specifications for the RA30H4047M, it can operate in a linear mode depending on how it's implemented. So the module could do it in theory.
Hey! I have a few videos on my QO100 build for DATV, that uses an Original Pluto with modded firmware. Slightly different configuration as QO100 requires a 2.4GHz uplink. I'll revisit this project in the near future as there does seem to be some interest in it. Cheers!
You are not that far away, depends on the hills. The limiting factor with the PA will be spectrum regrowth. Assuming it is a genuine one of the modules, they are good for about 5W before they get too nasty, but only if you up the bias. Perhaps the low/high switch does that. One issue you may find is the isolation of the relays is not great, so if you up the bias the gain will be high and it might oscillate. You might want to modify it if you use it for DATV to prevent that. You will need a low pass filter on the output. The power reading won't be reliable without a filter as the harmonics will fool the meter. As it is, 5W will do for local QSOs. It may be a useful driver for a bigger PA. Edit - so bias it up to a couple of amps of standing current and run it at 5W and it should be OK. You will need a fan on top for DATV as it is key down, just like your QO100 PA.
VERY interesting topic, however 2 items... #1 SO-239 connectors at 400 MHz are garbage. #2 is it rated for digital on/off rapid fire cycling? Your testing is for FM and I'm not sure if DATV uses FM or not. Is it is more like DVB-T ? Perhaps it's not an FM transmission and that amp could be useless for that particular application. #3 I would back off whatever the max power is listed so as not to burn out that final Mitsubishi PA chip. They are NOT 100% duty cycle and I think that is almost what is needed for DATV. I hope that helps. Stay hungry and Stay curious!
@@TechMindsOfficial yes, there is an input attenuator on the board, but this module is rated at 30 watts. You reach 30+ watts on the LOW1 setting already, which is 30 miliwatts.
What horrible internal construction! If I purchased this, would most likely re-build it into a smaller case, with tidy construction, N or BNC connections, a power pole inlet and output filtering if it does not have any!
So many great videos on this channel recently. Things I'm not seeing elsewhere too which is awesome.
Glad you like them!
The best time to catch some 70cm DATV activity is on one of the BATC activity weekends. Be very careful not to overdrive these modules or you will destroy the input stage. I always use a variable attenuator to slowly drive them up. For DATV use, you need very linear class A operation, which is not how commercial amps are usually set up. On class A operation, the quiescent current is not much less than that at full power so they are often only 25% efficient.
defo get a spectrum view of that Mitsi chip output - that package is notorious for harmonics, and i suspect your power reading will take a dive when you LPF it.. Maybe it's different on the 400Mhz variant, but the low-band VHF one (good for 4m) is a stinker for harmonics.. just FYI
The only filtering on this is done by the internal matching of that amplifier monoblock, it's definetelly not recommended to run it at full power with something like an SDR without other filtering, bandpass, not a lowpass.
Yes datv with pluto plus, would be very interesting.😊
Always neat stuff for the hobby!
The Mitsubishi amplifier is a good one. Be interesting to see how they've biased it: it runs in Class C unless you waft a bit of bias voltage at it.
You probably won't get anywhere near the power output of your handheld's NFM signal with the bandwidth of a DATV signal for the sake of linearity. Also it would be good to know the class of operation. If it won't work on SSB you likely can't use it for DATV.
There is no delay or PTT control, so SSB would be no no. However, Im not sure what you mean regarding "if it wont work on ssb you likely cannot use it for datv". I have built 2.4GHz amplifiers that used certain pallets which did NOT work on SSB but worked amazing on DATV. It will be interesting to see the power output once I use a 333k/s DATV signal on the input! :-) One can only try and cross fingers and legs lol.. Cheers
@@TechMindsOfficial I did not think an OFDM type signal would work properly with say a class C type amplifier. I'm thinking that amplifier is mostly meant for FM handhelds. If you have different experience it will be interesting to see.
I guess it's not OFDM. It's based on DVB-S. Which doesn't work well with a class C amplifier. But what do I know. Have fun. Good luck!
I think you are right concerning it's original design, it's meant for handheld. There is a website online, Enigma web shop which sells these modules and a separate PCB which looks really interesting as it supports PTT. If you do not see a video of me using DATV with this amplifier in the next few week, you will know it didn't work! lol. Cheers mate.
@@TechMindsOfficial Looking at the specifications for the RA30H4047M, it can operate in a linear mode depending on how it's implemented. So the module could do it in theory.
DATV on UHF sounds interesting - at least more interesting than FT8 on HF😀
Hi, down in VK we use the LimeMini for DATV. It would be interesting to see the setup for the Pluto.👍
Hey! I have a few videos on my QO100 build for DATV, that uses an Original Pluto with modded firmware. Slightly different configuration as QO100 requires a 2.4GHz uplink. I'll revisit this project in the near future as there does seem to be some interest in it. Cheers!
Cb/ham liner use on 10 meters radio on galaxy connex
You are not that far away, depends on the hills.
The limiting factor with the PA will be spectrum regrowth. Assuming it is a genuine one of the modules, they are good for about 5W before they get too nasty, but only if you up the bias. Perhaps the low/high switch does that. One issue you may find is the isolation of the relays is not great, so if you up the bias the gain will be high and it might oscillate. You might want to modify it if you use it for DATV to prevent that. You will need a low pass filter on the output. The power reading won't be reliable without a filter as the harmonics will fool the meter. As it is, 5W will do for local QSOs. It may be a useful driver for a bigger PA.
Edit - so bias it up to a couple of amps of standing current and run it at 5W and it should be OK. You will need a fan on top for DATV as it is key down, just like your QO100 PA.
Thanks for the vid made.
are 33cm 23cm 13cm 9cm 6cm 3cm 1.2mm and higher ones even used and what is on them
VERY interesting topic, however 2 items... #1 SO-239 connectors at 400 MHz are garbage. #2 is it rated for digital on/off rapid fire cycling? Your testing is for FM and I'm not sure if DATV uses FM or not. Is it is more like DVB-T ? Perhaps it's not an FM transmission and that amp could be useless for that particular application. #3 I would back off whatever the max power is listed so as not to burn out that final Mitsubishi PA chip. They are NOT 100% duty cycle and I think that is almost what is needed for DATV. I hope that helps. Stay hungry and Stay curious!
don't overdrive that amplifier. 100 miliwatts of RF is perfectly enough for it to function to its maximum rated output.
That maybe true but I think there is an input attenuation.
@@TechMindsOfficial yes, there is an input attenuator on the board, but this module is rated at 30 watts. You reach 30+ watts on the LOW1 setting already, which is 30 miliwatts.
What horrible internal construction! If I purchased this, would most likely re-build it into a smaller case, with tidy construction, N or BNC connections, a power pole inlet and output filtering if it does not have any!
If if if
Bishi not Bushi. 😉👍
I see no filter