Rice boxes on AM - Icom 7300?

Discussion in 'Amplitude Modulation' started by W8EJO, Apr 18, 2016.

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  1. KD2BRM

    KD2BRM Ham Member QRZ Page

    I have messed with it numerous times. I have one of the earlier ones with no new firmware updates etc. The audio is not terrible on AM, but the damn ALC just does NOT let the modulation reach full potential. I always sound somewhat "PISS WEAK". I've gotten it to sound halfway decent, but nowhere near as good as my past FT1000D. I've tried the ALC trick with the 9V battery, and a bunch of other crap.

    It's a great SSB rig, and that's what I originally bought it for. AM was kind of an after thought as well for me, until I made friends with some 75M AM guys in my area. It's really a shame the way they make these new Riceboxes. How much more $$$ would it cost them to bypass the ALC circuit for AM. Hell................ they can probably just do it with firmware today.

    I'll try and search for what you were saying as well. Maybe there's some newer info out there that I'm not aware of. For now though, The ANAN is go-to AM rig. Definitely HI-FI !! hi,hi
     
  2. KD2BRM

    KD2BRM Ham Member QRZ Page

    Great job on the video, & Thanks for putting this up. I'm curious though, you mentioned when in SSB mode that you were running no drive power. Were you also running no Carrier as well when you were in AM mode ??? The reason I ask, is because my FTDX3000 sounds great into a dummy load, and listening to it on my ANAN as well, and to extreme locals within a mile or so. When I put out a carrier, is when the ALC molests my modulation.
     
  3. KD4MOJ

    KD4MOJ Premium Subscriber QRZ Page

    DUHHHHHhhhhh........... I guess I didn't read down enough to see that. Teach me to read ALL the post before I answer! :)

    ...DOUG
    KD4MOJ
     
  4. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    Been there, got the Tee-Shirt to prove it :D
     
  5. KE5GBC

    KE5GBC Ham Member QRZ Page


    I've poked my toe in AM a few times but recently I've got more interested based on the conversation. I've been using a 706 with no complaints but maybe guys have just been nice.

    I'm trying to figure if it would be worthwhile to get the filters to put my k3 on Am. Supposedly using the fm filter it will go 8kc as the dsp limit is 4.2.
    Any thoughts appreciated.
     
  6. KA4KOE

    KA4KOE Ham Member QRZ Page

    4.2 KHz wide sidebands will work great. Radios hardwired so to speak to cut off at 2.9 KHz don't work all that well on AM. My Valiant modulates normally at 4 KHz and will go as wide as 5.2 KHz on sibilant sounds. Of course I'm using an RE320, Inovonics 222, and a Symetrix 528E, plus Timmy's mods (exclusive of new mod iron and toobs).
     
  7. KA4KOE

    KA4KOE Ham Member QRZ Page

    And btw, for any of you folks with FT897/857s, International Crystal still DOES have the 3.8 KHz wide Collins filters although their site does not show it. Email them.
     
  8. KA4KOE

    KA4KOE Ham Member QRZ Page

    GBC, my friend got on last night with his FTDX3000. It didn't sound half bad, but he was using a Heil headset boom microphone. Put a decent microphone into it and widen up the response to 4 KHz via that menu item and it should do fine. I don't know about the ALC, but you likely could correct that via injecting a voltage into the rear ALC jack as W8JI describes. I didn't do that on mine and just adjusted one of the hidden menus on the 897 and it doesn't do that bad either.
     
  9. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    I just had my first AM QSO on HF (7.290) with W2PFY. That was about 30 minutes of wholesome AM fun! I heard him testing a beautiful BC-610 that's been cantankerous and we helped each other tune up our rigs and laugh about things in general.

    My setup for AM is an FT-857/SB200 running about 150 watts carrier until I can get a chunk of time to finish up the DX-60 stack (hopefully July). For now, this little box o rice is working very nice!
     
  10. K5UJ

    K5UJ Ham Member QRZ Page

    For years I ran a Yaesu FT1000MP Mk V on AM. I still have it and run it driving 2 x 3-500Z on 160 because I don't have any plate modulated rig on that band that can put out 300 watts or more. The 1000MP is old enough to have some analog sections and through-hole circuit board parts. On AM, it can put out up to 50 watts so as a 20 w. exciter it can run with no time limit (as far as I know) provided the internal fan keeps moving.

    Anyway, the nice thing about it is that the only filter of consequence in the signal path when AM is selected is a small Murata ceramic 6 kc filter that's in the 455 kc converter stage right after the balanced modulator. Pull that filter out and put a small jumper wire connecting the in and out pads on the PC board and you have a nice flat AM rig that is limited by your baseband audio low pass filtering. You can bypass the front end mic preamp and feed the balanced modulator via an isolation transformer to a coupling cap on the bal. mod. input.

    You have to be kind of careful when looking for a plastic radio, especially the ones that have all this firmware encoded you can't modify. The Kenwood TS870 is programmed to not allow any positive modulation above 70% on AM. You can't do anything about it. Great slopbucket rig but it sucks on AM. That's an example of how you have to read the fine print. I can't comment on SDR as I have had no experience with any of that but if you want a regular box with knobs and a front panel, I'd look for an older rig that is analog that you can modify and possibly work on.
     
    W2VW and KD2ACO like this.

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