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zBitx with external Amplifier
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Pierre - FK8IH
If I buy a zBitx when I use it in the shack I plan to add a QRP-Labs 50 Watt Amp. This full QSK Amp needs a stereo wire with +5V and ground put into the Amp stereo 3.5 socket to be triggered in transmission.
Does the zBitx have this 3.5V stereo PTT socket? If not it should be easy to add one but where in the schematic will I find the necessary +5V signal to trigger the Amp?
73 - Pierre - FK8IH |
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Pretty sure the QRP Labs 50w is for just one band.? You build it for a specific band, example 40m and you won't be able to use it on others.? On Tue, Feb 25, 2025, 4:28?PM Pierre - FK8IH via <jb.gallauziaux=[email protected]> wrote:
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Pierre, typically a relay output from a radio GROUNDS on transmit.
With a tiny bit of circuitry you could turn that into a +5V or any other signal that you need.
I have elsewhere showed how to create an optically isolated output to control such a linear
See: ? /g/BITX20/message/106371
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However, I think I have seen that newer Sbitx may come with this.??
I don't know if there is enough room in the zbitx?
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The important thing is to use DIGITAL inputs to control such a circuit, never the analog TX lines -- exposes too much risk of RF getting places it shouldn't.
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Once you have ANY kind of output that is appropriately safely isolated, a little bit of circuitry and you can control just about anything.? ?
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Hope this is of SOME help
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Gordon KX4Z
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Pierre - FK8IH
David, if I build the QRP-Labs 50 W Amp with the 20M band LPF then plug into the output BNC socket either a 30M or a 40M LPF and then the coax in the Amp BNC socket for 20M or in the 30 or 40 LPF output BNC socket for these bands, I will get a 40M, 30M and 20M Amp on my favourite bands.
()
This Amp and LPF filters will just cost US$ 45.50
73 - Pierre - FK8IH |
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开云体育Those are pretty small toroids. ?I have had a “blue” high voltage cap catch fire because of high ESR wonder what losses are in those filters? For ME I would prefer fairly BEEFY low pass filters at 50watt level; but these may be fine. ?Just don’t know? Gordon kx4z? On Feb 25, 2025, at 22:00, Pierre - FK8IH via groups.io <jb.gallauziaux@...> wrote:
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开云体育Is your plan for CW only?Their manual states designed for class C only & usage beyond that is considered “experimental” Very interesting amp for what it was designed for!! Thanks- Gordon kx4z On Feb 26, 2025, at 02:59, Gordon Gibby KX4Z via groups.io <docvacuumtubes@...> wrote:
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Hello Pierre,
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I believe your cost estimates are low.??
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For $25 more, you can get a linear amp based on the WA2EBY design offered by AmateurRadioKits:
Note that the picture is for the older model that does not include the 80-meter LPF.
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The case is included, and the band is switchable on the front panel.? I suspect you will spend close to the difference in adapters and enclosures for the LPF filters.
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I built the prior version of the WA2EBY offered by AmateurRadioKits and found it a sound amplifier.? Low harmonic output and IMD measurements? I did modify the band switching circuit and the bias power source to allow for operation on 12 volts at lower power.? I used a buck-boost DC to DC converter instead of the amp board Zener and the filter board linear regulator to power the bias and selection circuits.? That allows me to run the amp from 10 volts to 24 volts.? At 12 volts, I get 18-20 watts output.? For digital modes, the carrier switch PTT works well.? I do not yet have an SSB rig with less than 5 watts of output to try that mode.? I will do so when the QMX SSB update is available.? I suspect I will need to add a hardware-based PTT line to the amp.
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73
Evan
AC9TU |
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No one answer the question, but with the Sbitx a much bigger radio this simple interface was left out. A "third party" became available but required a bit of soldering and a interposing relay isolation circuit to be installed. Hardware Modifying the Zbit is going to be even more difficult due to its size and construction techniques.?
This question should be directed to and answered by documentation or directly from HF signals?
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Patrick? |
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Hi Patrick,
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Can you clarify the question that has not been answered???
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As to the PTT on the zbitx, if needed for SSB (the digital modes should work with the COR circuit in the WA2EBY amp), the Pi Zero uses the same GPIO connector as the RPi 4 and 5.? It may need to be external, but it should be within most kit builders' skill sets to build external isolation, as Gordon did for the sbitx.? As you stated, we must wait for the documentation before we know definitively.
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73
Evan
AC9TU |
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Pierre - FK8IH
I got the following answer from HF Signals:
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Hello Pierre,
The zBitx doesn't have a dedicated PTT output to trigger an external amplifier. You might have to do some DIY to get a PTT output and also modify the case to accommodate the connector.?
I will have a word with the technical team about the PTT signal and get back to you.
73,
Ragav VU3VWR Unquote
Maybe this thread and some comments will show them that adding a PTT socket would be useful on a 5W transceiver, which is just at the early stages of its development.
73 - Pierre - FK8IH
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