| Author |
Message |
    
Bluebird
Intermediate Member
Username: Bluebird
Post Number: 157
Registered: 2-2004
| | Posted on Saturday, September 10, 2011 - 1:15 pm: | 
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i have a ft 707 that dead keys to about 90-100 watts
but as soon as u modulate it drops to about 20 watts and current drain from 18 watts to 6-8 amps,,,ssb is fine..using a 25 amp power suply mfj 986 tuner & 4 elem quad,,need advice thanks
mitchell
bluebird
cef 398
cvc 113
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Scrapiron63
Advanced Member
Username: Scrapiron63
Post Number: 882
Registered: 12-2001
| | Posted on Sunday, September 11, 2011 - 1:18 pm: |
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You're running it too high on keyup and it's probably cutting the power down to prevent damage.
Most HF rigs are not great on AM anyway but that's way too much keyup. Drop it to about 20-25 watts and you might see some forward swing. |
Starface
Senior Member
Username: Starface
Post Number: 3056
Registered: 1-2005
| | Posted on Sunday, September 11, 2011 - 2:23 pm: |
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Running at 90-100 watts you need more then just 25 amp power supply , try it at 35-45 amps and see what you get. |
Bluebird
Intermediate Member
Username: Bluebird
Post Number: 158
Registered: 2-2004
| | Posted on Sunday, September 11, 2011 - 8:12 pm: |
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ok thanks i tryed both,but did not help,,i got my hands on a manual and it stated on am i should turn up carrier with alc switch on until the 4th light lights up (80watts) and turn up mic gain with audio until 5th light comes on,,works good...
thanks all!!!
mitchell
bluebird
cef 398
cvc 113
|
Tech833
Moderator
Username: Tech833
Post Number: 2043
Registered: 8-2002
| | Posted on Monday, September 12, 2011 - 4:46 pm: |
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25 amp power supply is plenty for an FT-707. Yaesu recommends a 20 amp or more power supply.
The FT-707 is like most other amateur "rice box" radios on AM. It's not "true AM". It's more like a carrier with a sideband (or two if you're lucky) added on. The trick to getting one of these to work well on AM is measure the peak power output, then set the carrier to 25% of that level. Keep an eye of the ALC and keep it just below mid range on audio peaks.
These radios really excel on sideband, not so much on AM. But, since AM is usually only used on 160m or 80m bands, and only by a fringe minority of hams, they don't seem to give much thought or engineering to the AM performance anymore.
If you want a real stellar performing AM transceiver, look for a separate transmitter / receiver pair. Collins 32V (and it's derivatives like the 32V-2, etc.) and the Johnson Viking line teamed up with a matching quality receiver is hard to beat on AM.
But, overall, I really like the FT-707 because it has a nice LED frequency display instead of the generic LCD backlit displays seen today with no personality at all.
Your radio 'Mythbuster' since 1998
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Big_mac
Junior Member
Username: Big_mac
Post Number: 16
Registered: 11-2011
| | Posted on Thursday, November 24, 2011 - 10:11 pm: |
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bad final or driver |
