Modulation Help (AM)

[heres johnny]

so im in kinda the same boat -- ic7100, good power supply, dipole at 65', but the one thing i found frustrating was the limited bandwidth -- 6 kc as opposed to 10 kc most radios around here would listen to.  do you just fire out what the 7300 does naturally or did you find a way to broaden the tx bandwidth on AM?

edit: yeah i just checked a buddy's kiwi, most sw stations are pumping out 10 kc

[Stretchyman]

Its +/-5KHz as the modulation B/W is x2 the max audio frequency.

Best to use a REAL A.M. transmitter!

However if you inject audio directly into the mixer you may be able to bypass some filtering, that and obviously changing the I.F. filters.

Str

[heres johnny]

yeah, probably.  got any suggestions for cost-effective txers?  i have a pretty legit ham setup, so whats ONE more radio right?? haha

[RobRich]

Bandwidth aside, some Icoms can benefit from the "external ALC" mod to better tweak the carrier and modulated power output for AM transmitting. It is basically just a pot and battery connected to an accessory port.

For standalone rigs from the "big three" brands with possible wider audio bandwidths, take a dive into the ESSB communities and forums for ideas. Otherwise some of the newer SDR transceivers like from Anan and Flex can go to 20KHz at least on SSB. See here:

https://www.nu9n.com/essb_ready_rigs.html

[heres johnny]

yeah flex can do it for five THOUSAND dollars.  hard pass on the kilodollar investment in a hobby for the lulz

[Shortwave_Listener]

yeah flex can do it for five THOUSAND dollars.  hard pass on the kilodollar investment in a hobby for the lulz

Not to mention the Flex won't do out of band. If you are looking at 6.9 MHz or 11 meters, the Hermes Lite would be decent with a high gain amp to go with it.

[radioartisan]

Not to mention the Flex won't do out of band.

Really?  That's why I don't have an Elecraft K3 or K4.  Well, that, and it takes them two to three years to ship a rig after they announce it in Dayton.

[Shortwave_Listener]

Not to mention the Flex won't do out of band.

Really?  That's why I don't have an Elecraft K3 or K4.  Well, that, and it takes them two to three years to ship a rig after they announce it in Dayton.

Everyone I have talked to says they need a valid MARS license for the software to allow out of band transmit.

[radioartisan]

Everyone I have talked to says they need a valid MARS license for the software to allow out of band transmit.

Interesting.  All the commercial rigs I have require just a web browser, search engine, and a soldering iron to allow out of band transmit 

[RobRich]

IIRC there is "unlocked" software for the old Flex 1000, but it does not surprise me about Flex regarding newer models. Took a quick skim. Apparently Flex went to “TURF” files for setting various frequency ranges. Hmm.

There are various SDR-based QRP rigs on the market, but yeah, the Hermes Lite 2 is definitely a popular enthusiast-class network radio. Main PCB, filter board, I/O board, and enclosure for ~$400.

To get above QRP with an affordable off-the-shelf amp, there is the small PA-50+ on AliExpress and similar. Curious if the newer "plus" version resolves the ~1.5:1 SWR limit on the older model, as AFAIK the older model usually required a resistor mod to tweak the reading for wider acceptable range. Anyway I suppose the bigger issue would be SSB versus AM, as I suspect AM without serious clipping and other distortion artifacts would be to be more like 5-10w carrier.


BTW, there is still the $220 50w (PEP!) AM HF transmitter on Etsy. That said I have no real idea on max audio width, low pass RF filtering etc. I would not really surprise me if we have logged a few such transmitters here at HFU over the years.

[radioartisan]

There are various SDR-based QRP rigs on the market, but yeah, the Hermes Lite 2 is definitely a popular enthusiast-class network radio. Main PCB, filter board, I/O board, and enclosure for ~$400.

Is the Hermes fairly straightforward to get going?  I have a LimeSDR that I got during the COVID and didn't do much of anything with it.  It just seemed to be too complicated and too much of a pain.  I write code, build rigs from scratch, make 2N2222s do things they probably shouldn't, and run Linux / BSD / etc. so I'm no dummy.  (I should probably revisit the LimeSDR and try to do something simple with it.)

[Shortwave_Listener]

There are various SDR-based QRP rigs on the market, but yeah, the Hermes Lite 2 is definitely a popular enthusiast-class network radio. Main PCB, filter board, I/O board, and enclosure for ~$400.

Is the Hermes fairly straightforward to get going?  I have a LimeSDR that I got during the COVID and didn't do much of anything with it.  It just seemed to be too complicated and too much of a pain.  I write code, build rigs from scratch, make 2N2222s do things they probably shouldn't, and run Linux / BSD / etc. so I'm no dummy.  (I should probably revisit the LimeSDR and try to do something simple with it.)

Mine wasn't too hard. Build the kit (very easy, just putting two boards together and adding some thermal paste) and then I connected mine directly to the computer (rather than through a network). Thetis has a long initial bootup that confused me because I couldn't find any info about that. Once it was complete it was pretty much working, although the software stills needs some tweaks to get transmit to work, and a few other things for ideal operation.

[RobRich]

Unless experimenting with new features, the process should be mostly straightforward as the base HL platform is relatively mature at this point. There are various guides, FAQs, and communities to help. As S_L noted, the software can be little involved to setup, but that can be true of many SDR products.

Fellow Linux user and occasional software tinkerer here, too. :)

[sternradio666]

yeah, probably.  got any suggestions for cost-effective txers?  i have a pretty legit ham setup, so whats ONE more radio right?? haha

An FT-101 with a linear? Fire your audio straight into the AM modulator board, skipping internal mic amp.  Need to make a few other little changes on that board as well to get sexy AM out of it.   Easily can make an FT-101 go 10kHz wide and do so rather cleanly, too!  The 101 by itself is good for about 35W AM carrier., especially if you're really modulating the snot out of it.

You can adjust the idle current to be a bit lower if you are only going to do AM with it, that'll keep the heat down on the finals some without any real issues.