Re: ALC: issues raised almost 2 month ago + answer from Elecraft
Locked
Re: ALC: issues raised almost 2 month ago + answer from Elecraft
 
|
There are amps out there that will do full legal limit in RTTY all day long with the
exciter at 30-50W. Some of these amps are not stressed at all at that level and are just loafing along happy as can be. :) ------------------------- 73, Greg - AB7R Whidbey Island WA NA-065 K3#0009 On Mon Dec 3 17:18 , David Wilburn sent: >I admit, I may not be the sharpest knife in the drawer, but to see a >reference to an amp, and the words 'full power' and RTTY, all together? >Wow. That raised my eyebrows. > >With the power density of RTTY, isn't that a full blown stress test of >your complete RF system, at 100% duty cycle, or so...? Any standing >waves on the thing would be huge, and wouldn't the safety factor would >be a negative number? > >Aren't you taking on a bit of risk to your system? Please don't take >the wrong way, I am trying to learn. Being one of those no-code techs >we hear so much about. I am just rationalizing the described activity, >with all these warnings I see on various equipment, about high duty >cycle modes. >- > >David Wilburn >[hidden email] >K4DGW >K2 S/N 5982 > > >On Mon, 2007-12-03 at 16:43 -0500, Jerry Flanders wrote: >> At 02:59 PM 12/3/2007, Enno, PF5X wrote: >> >Hi gang, >> > >> > A very >> >quick response from Wayne gave the following info. Sufficient to cool the >> >discussion for a while I would say ... >> > >> >> Not so - Wayne's comments seem directed at those who might want to >> use ALC as if it were a substitute for the mike gain control. >> >> It worries me when I see the discussion wander away from amplifier >> safety in an antenna catastrophe situation, which is my main concern. >> I once blew up the output circuit of an AL1200 due to an intermittent >> in an antenna coax while running full power on RTTY. >> >> Please see my other in-line comments below. >> >> >-- >> > >> > >> >From: wayne burdick [hidden email] >> > >> >Date: Fri, 12 Oct 2007 14:12:24 -0700 >> > >> >To: [hidden email], [hidden email] >> > >> >Subject: regarding external ALC >> > >> > >> > >> >Hi Enno, >> > >> >Transmit power control via the ALC input (AUX I/O pin 15) is planned, but >> >not finalized. We're mindful of the negative impact ALC can have on transmit >> >signal purity, a subject of recent debate within testing organizations. >> >> Speaking only for myself, I do not intend to adjust the ALC to >> provide normal level control - only a crisis shutdown function. >> Quoting from my Quadra's manual p4.: >> >> "The ALC cable must be connected between >> the transceiver and VL-1000 to >> prevent overdrive of the amplifier, and especially >> to facilitate the proper operation of the >> protection circuitry if sudden antenna system >> problems should cause the SWR to rise to dangerous >> levels." >> >> Rightly or wrongly, Yaesu (and probably ICOM) engineers have presumed >> the ALC would be functional and could cut back exciter drive in the >> event of an antenna catastrophe. Other main-line rigs that I am >> familiar with are compatible. I think it is reasonable to assume the >> world-class K3 would have provided for this also. >> >> BTW - It is worrisome that ALC was only planned, but still not >> finalized, as of Oct 12. >> >> >> > Once ALC is working to our satisfaction, we'll provide simple interfacing >> >information that will allow the use of negative control voltages ... >> >> I, and perhaps other Solid State amp users, would prefer a definite >> calendar commitment, if that is possible. If not possible, please >> state so. I would hope for a working, properly engineered >> negative-going ALC fix within a few months. >> >> >Meanwhile, the K3's DSP-based early-stage ALC is very effective at >> >preventing amplifier overdrive, and should suffice in nearly all cases. >> >> I repeat - my concern is amplifier safety, not a substitute for a >> mike gain control. Sooner or later, the antenna will fail, but we >> don't know when, and we probably cannot manually cut back drive >> quickly enough to protect those expensive SS finals when it occurs. >> >> >73, >> > >> >Wayne >> > >> >N6KR >> >> >> Jerry W4UK >> >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com > >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: ALC: issues raised almost 2 month ago + answer from Elecraft
Administrator
|
I used to run 5KW AM all day long myself with nary a break. Had to
check the plate current every half hour or so but that was about it. I think the amp was using 813's but I can't remember. Of course, we were on 300 meters back then. 73, Leigh/WA5ZNU On Mon, 3 Dec 2007 2:41 pm, Greg - AB7R wrote: On Mon, 3 Dec 2007 2:41 pm, Greg - AB7R wrote: > There are amps out there that will do full legal limit in RTTY all day > long with the > exciter at 30-50W. Some of these amps are not stressed at all at that > level and are > just loafing along happy as can be. :) > > ------------------------- > 73, > Greg - AB7R > Whidbey Island WA > NA-065 > K3#0009 Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: ALC: issues raised almost 2 month ago + answer from Elecraft
|
|
>" I think the amp was using 813's but I can't remember.
The amp I ran used 833's -- ran for months at a time on full power. Double sideband full carrier. Mark _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
«
Return to Elecraft
|
1 view|%1 views
| Free forum by Nabble | Edit this page |