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Please explain with a schematic, hand written might be fine as well.

Thanks for your answer.

Flashing the Raduino software once again solved the problem.

Opto couplers and fets for switchinn what ones work best at 30mhz?

I use that a lot at DC and power line AC but RF.... no.

Allison

For VHF and UHF in NE USA.? Been doing this for nearly 20 years and?
FM is not a thing its all weak signal modes.

All of the digital voice modes (D-star, PMR, Fusion...) are on repeaters and internet(combined).

I use a Ft817 on VHF/UHF and there are no mode limitations other than power.
That is for portable work, amps optional (bigger battery).

For home:
For VHF and up contests the 6m and 2M radio is either home brew or Tentec 6n4 (model 526).
And amps as needed.? For 432 I use the 817 and a TV TX driver amp (100W).??
None of that allows for HF gear as well.

FM, seriously?? Allowing for FD and Winter FD and the three annual ARRL VHF/uhf contests
IF I do 10 FM contacts for the year during those combined it is a big deal.? Its a lousy weak signal
mode and range on simplex is far shorter per watt.? There may be places where that is a "thing"
but not for a 100mile radius around here FN42.? The only FM DX ever heard was 10M FM during
the peak of the 2001 solar cycle.? I ahve worked DX on the low end of the cycle on 10m SSB.

The hot modes are digital (need SSB), SSB and CW pretty much in that order too.
And for digital its FT8 mostly, JST65, PSK31 and maybe FSK441 are used but FT8 seems
to have displaced them.

Generally most commercial radios are far less limited? than any home brew effort.
For example for all possible mode what mode cannot any of these radios do?

simple sample:
?FT817/818
?IC7300
?Tentec Eagle
?FT990
?
? Every one does CW, SSB, AM, all SSB data modes and FM data modes (APRS/packet mostly)
? Slow scan, RTTY, Feld-Hell.? If I missed one its only another name.
??
About the only mode they do not do is fast scan TV (limited to 420 mhz and above here).

So FC what modes are missing?

A multi mode multi band VHF radio is about the? most difficult radio task one can take on.
As you need mostly separate everything for each band save for IF, Switching, front panel stuff.
A VHF amp does not work on UHF and those that do are dual amps in one box.? ? ?Generally
speaking anyone with skills enough to design or build that would not have asked that question.
Kits are scarce and never cheap usually limited to transverters and then you need a competent
HF radio at low/nearly-no power.? That and a tower full of decent antennas.

Allison

Hi Terry,

A monobander can't be directly compared with a GQ HF rig for value. I think the QSX will prove a better quality radio than the uBitx but the model with all the bands will cost noticeably more - at last blush Hans was estimating $150. It could be more. I intend to have one.

<OFF TOPIC ALERT> Hans also has the QCX radios that are single band CW only quite a bit less than the uBitx and I think maybe a bit less than the Bitx40. The QCX also has WSPR built-in. I do not use WSPR so for me it is a single band, CW only rig. I was about to start ordering some of those when I had the chance to get a Hendricks PFR-3 at an attractive price. It needed repairs which I did *immediately* :) Now I only need the 80 meter and 17 meter QCX. I will still use the uBitx and of course, the QRO radios. 100 watts! EEYOWEE! <END OFF TOPIC> You can come out from under the bed now <evil grin>.

Happy New Year and 73,

Bill KU8H

--
bark less - wag more

Hi,

A couple of things. There are band opening on ten meters even with the solar activity being low. Looking at the calendar or some MUF web site will never tell you when there is an opening, even when the sun is very active. The way to find out about openings is to turn the radio on and listen, make some CQ calls.

And..the thread turned to using a transceive converter into an HF rig to do the digi modes at VHF and UHF. It was pointed out that some of those use SSB and a stock uBit will serve nicely. Some are FM and the HF rig has to have the FM mode for that to work. The uBitx won't work for that unless an FM strip is added for both receive and transmit. There are some HF radios that will do FM. This is the Bitx list.

Adding FM to the transmit IS harder to do that on receive. For that matter, so is SSB. And gosh, CW transmit is also harder than CW receive. Hams have been doing all of that for decades:) Just because there are newcomers here doesn't mean they can't do it too. They're hams now. They can roll up their sleeves and wade in with the rest of us. Our friend who wants to play with new ideas at VHF and UHF is surely a brave adventurer.

However it is done, the HF rig can still be used on the HF frequencies without the converters. Never mind that we can't use FM on forty meters. Switch it back to CW or SSB on forty:)

Happy New Year and 73,

Bill KU8H

--
bark less - wag more

In principle I would agree with Warren. But where did you put the RX amplifier? Where exactly in the schematics? I would say that artifacts in the receiver may be buried by the added sensitivity, so that the noise from the antenna fully covers any noise generated within the receiver. At the cost of possible overload or limited dynamic range. However you can't go wrong as you can deactivate it.

--
thanks and 73's
Bret
WX7Y

Thank you,? Raj.?
--
73, Al - va3iaw

To me FM is an inferior mode. SSB is much more narrowband, average power is much less and you save finals and or battery. I guess FM allows faster data transmission because its more wideband so for sending an email over radio might have a purpose. As for satellite operation, the stronger FM signal win, SSB is more democratic many more than a QSO at the same time may occur at any power level.

I agree that it is more a matter of preference, however there is a true technical issue that adding more gain in the AF section would solve the same problem:? That is what is the source of the noise?? If it is coming from the antenna, then Warren is correct, more AF gain would give the same result.? If it is internal to the radio (maybe the AF amp is more "noisy" as the gain is increased), then adding the RF gain could solve that problem.??

Harvey, would be interested to see what you do to add both RF amp and AGC using that amp.? There are other solutions for the AGC that the ubitx needs badly, however adding back the gain for low signals would allow addition of high pass filter to reduce external interference from commercial stations would be of interest to me.? Maybe even a pre-selector function.? Besides, any RF AGC would reduce input sensitivity just due to the added components in the input.

73
Evan
AC9TU

In that case Harvey, you could accomplish the same thing with adding more AF gain. It is not a big deal...... but adding RF gain when you already have detectable antenna noise reduces the dynamic range of the receiver making it more susceptible to overload.?

It is somewhat of an "angels on the head of a pin" discussion. Just ignore me..... :-).

WA8TOD

Warren, I don't completely agree with you. Without the amplifier, the noise level does increase when the antenna is connected but I have found with my testing that some weak signals can be heard much better with the amp connected. My test set up allows me to bypass the amp easily so I have done some tests on weak signals just above the noise. The amp does help to hear them much better. My two cents.

Happy New Year.

Harvey, WA2AAE

It would be great to have a V-U Bitx! If it was full duplex too, you'd get the attention of the satellite operators quickly!

Ron

The advantage that SSB and CW have over other modes accrues as a result of the detection bandwidth used and much less the result of the modulation method. AM is typically detected in a 5-10 kHz bandwidth, SSB in a 2.4 - 3 kHz BW, and CW in a 100 - 400 Hz BW. The advantage each of those modes has is inversely proportional to the detection bandwidth. The exception to that rule is AM where a significant amount of the power is "thrown away" in the carrier and does not contribute to the modulation.

Digital modes like WSPR and FT8 use the SSB bandwidth for reception but then use a much more narrow bandwidth for detection inside the computer software. So the reception bandwidth is whatever your receiver uses for a filter, typically in the 2.4 - 3.0 kHz range. But the detection bandwidth for FT8 is only 50 Hz and for WSPR about 6 Hz. When you get reception reports on these modes showing a negative signal to noise ratio, -17 dB for example, that number is generated by comparing the received signal level to the full bandwidth noise of SSB. Reception at negative signal to noise levels is nonsense but this number is easy to generate and makes for eye-popping stats.

Probably a lot more than you ever wanted to know....... sometimes I can't stop myself.

WA8TOD