[Hammarlund] HQ140 - really *LOW* sensitivity

[Joe Connor]

Is it like this on all bands or just on the broadcast band?
 
            Joe Connor


>________________________________
>From: Richard Knoppow <1oldlens1 at ix.netcom.com>
>To: na2x at yahoo.com; hammarlund at mailman.qth.net 
>Sent: Tuesday, January 15, 2013 3:59 PM
>Subject: Re: [Hammarlund] HQ140 - really *LOW* sensitivity
>
>
>----- Original Message ----- From: <na2x at yahoo.com>
>To: <hammarlund at mailman.qth.net>
>Sent: Tuesday, January 15, 2013 11:54 AM
>Subject: [Hammarlund] HQ140 - really *LOW* sensitivity
>
>
>I'm working on a HQ-140X trying to get it into working order. I've spent many hours trying to figure out what's going on with it but so far, no luck.
>
>The radio basically works, but the sensitivity is really low on it. Yes, the sensitivity control is at max. The only AM station I can pick up is our local 50KW clear channel station. It comes in about S4 on the meter. Other than being weak, it sounds OK.
>
>Here's the puzzle. Quite by accident, I had the aluminum cover off the variable tuning capacitors on top of the chassis. I noticed when I bring my hand near the antenna trimmer cap, the sensitivity comes way up. If I touch the trimmer cap, the radio really comes alive to the point where I think it's working as it should (if it would only stay like that). The local 50KW station almost pegs the S meter.
>
>To me it sounds like something in the antenna input circuitry but I've traced the wires to the switch and that area, checked the antenna coils for continuity, checked grounds, and haven't found anything. Should I continue looking in this area or does anyone have any other suggestions?
>
>I'm just about ready to through in the towel, I've spent way too much time on it. I really don't want to give up on this receiver, it's a nice one and it's in really good shape.
>
>Thanks,
>Bob NA2X
>
>  The antenna trimmer is right at the grid of the first RF tube.  If you get a signal by getting close to it it means the everything following is working OK. If the low sensitivity is on all bands something has happened at the band switch. I suggest cleaning it very thoroughly and examining it for any mechanical damage or loose or unsoldered wires.  You can also check for loose contacts by pushing on them with a toothpick. I would go over the whole band switch even though the antenna section is only a couple of decks. Certainly clean it thoroughly.
>
>
>--
>Richard Knoppow
>Los Angeles
>WB6KBL
>dickburk at ix.netcom.com 
>______________________________________________________________
>Hammarlund mailing list
>Home: http://mailman.qth.net/mailman/listinfo/hammarlund
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:Hammarlund at mailman.qth.net
>
>List Administrator: Duane Fischer, W8DBF
>** For Assistance: dfischer at usol.com **
>
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html
>
>
>