"Bob Henderson" <[EMAIL PROTECTED]> made an utterance to the drakelist gang ---------------------------------------------------------------------- Hi Mark & Drake team
Well, I'm not so much new to Drake gear, more of a returnee. I got my first Drake receiever a 2B + 2BQ combination about 35 years ago. Thereafter, I owned some B-line twins and then a C-line. I loved my Drake kit but when Drake exited the ham market I abandoned it in favour of a Kenwood (then Trio in the UK) TS930. I've been through a lot of radios since and still have many of them. My main station is currently a pair of Ten Tec Orions. But the nostalgia effect is at work here (probably I have too much time on my hands :-)) and I developed a powerful desire to find another C-line to refurb. I let my previous C-line go for a song around 20 years ago. I often wished I'd hung onto it. Anyway, back to the agc issue. I remember what the agc was like on my previous C-line and it didn't do what this one was doing. That said I didn't ever find much utility in the use of the fast setting. I always used slow for SSB and either medium or slow for CW. So I suppose I could have just ignored this problem and stuck with the medium and slow settings which were fine. I guess I haven't done that because I got this radio to refurb it and that's what I'm gonna do :-) I'm pretty sure that Garey was on the button when he said the problems sounded like "motorboating". As he pointed out this low frequency instability can often be attributed to inadequate B+ decoupling. In this case though, no amount of additional decoupling has had any useful effect. C76 may be faulty but it's a little difficult to get at to replace outright, so I tried another 1nF accross it on the track side of the board, which is easily accesible. That improved the situation but didn't cure it. Increasing the value to 10nF stops the problem dead. Fast, medium and slow settings all now sound just like I remember my old C-line did, so I'm going to count that as a cure and move on to the next thing. I don't imagine I will use the fast agc for much as I never did before but it's nice to have it sound as I remember :-) Thanks for your help fellas. It's good to have somewhere to come and compare notes. 73 Bob, 5B4AGN, P3F [EMAIL PROTECTED] www.5b4agn.net ----- Original Message ----- From: "Mark V. Johnson" <[EMAIL PROTECTED]> To: "Bob Henderson" <[EMAIL PROTECTED]> Cc: <[email protected]> Sent: Thursday, May 26, 2005 1:17 AM Subject: Re: [drakelist] R4C agc problem > > "Mark V. Johnson" <[EMAIL PROTECTED]> made an utterance to the drakelist gang > ---------------------------------------------------------------------- > Bob and Drake team; > I too am somewhat new to Drake gear and I found the exact same problem > with my R4B. I was certain I had a problem with the FAST AGC. Scoped the > AGC circuit and tried several things then I consulted some colleagues. > My Drake colleagues told me that copying SSB on fast AGC was going to > result in this distortion. That fast setting is about 25 msec if I > recall. Slow AGC is around 750 msec. The manual says to use the SLOW AGC > for SSB and most CW. The fast setting is for other applications. The net > of it is, I don't think this is a bug. > > Mark V. Johnson VE3DJU/VE3DDI > > Bob Henderson wrote: > > >"Bob Henderson" <[EMAIL PROTECTED]> made an utterance to the drakelist gang > >---------------------------------------------------------------------- > >Hi all > > > >I recently picked up an R4C which I'm now checking out. It's in pretty good > >all round condition and for the most part seems to work well. However, I > >notice a particular problem with the agc. If I set agc to medium or slow > >then all appears well but if I select fast the rx sounds awful. I scoped > >the af output from the rx and notice that when fast agc is selected, the > >audio output appears 50% modulated by a ~150 Hz ripple. It's not > >immediately obvious to me where that is coming from. > > > >Something is clearly not right here. I wonder if any of you fellas have > >seen this before? > > > >73, Bob, 5B4AGN > > > > > >---------------------------------------------------------------------- > >On Behalf of "Bob Henderson" <[EMAIL PROTECTED]> > >Submissions: [email protected] > >Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body > >Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > >Zerobeat Web Page: http://www.zerobeat.net > >Brought to you courtesy of TLCHost.net http://www.tlchost.net/ > >---------------------------------------------------------------------- > > > > > > > > > > ---------------------------------------------------------------------- > On Behalf of "Mark V. Johnson" <[EMAIL PROTECTED]> > Submissions: [email protected] > Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body > Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > Zerobeat Web Page: http://www.zerobeat.net > Brought to you courtesy of TLCHost.net http://www.tlchost.net/ > ---------------------------------------------------------------------- > ---------------------------------------------------------------------- On Behalf of "Bob Henderson" <[EMAIL PROTECTED]> Submissions: [email protected] Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ ----------------------------------------------------------------------
