[Hammarlund] HQ-129x recap

[William A Kulze]

Well, the recap is done and I went through the alignment, doing the IF according to the 'basic' instructions I the HQ-120 manual. Seems to be pretty good for not doing the sweep method. I've got a couple of spectrum analyzer modules that plug into a Tek 464, they only cover up to a Mhz or two, but it definitely covers audio and IF freqs. I'll try that at some point. The audio is nice and crisp, especially on SSB. I'm surprised at the stability, after a good warm up. I was listening to some 75m nets and only occasionally had to give the bandspread knob a little tweak. Sounded real good on the AM net on 3880. I have noticed that there is some nonlinearity across the dial, though. Both ends are right on, but as you approach middle of the dial there is an increasing offset where the actual freq is a bit below what the dial is tuned to as you get to the center of the dial. Maybe I'll take some readings through the bands and chart it. I'm considering replacing the resistors. Some of them have already been replaced but some of the old ones are off and one broke as I was desoldering it in order to do one of the caps.

This was my first total recap. I've done onesie twosie replacements, but not the whole rig. I'm gonna have to stock up on some caps, most all of the boatanchors I have are probably only in need of this and a good alignment.

Sure is nice to use the radio and leave it on for a while without having to worry about it suddenly crapping out.

Thanks for the input, guys!

73 de Bill W2NVD

-----Original Message-----
From: Robert Moses [mailto:rhmoses at earthlink.net] 
Subject: Re: [Hammarlund] HQ-129x recap

2 things to consider: 1: the specs on electrolytics are not that tight. 
2. If you are worried about inrush current at startup then put a low 
resistance resistor in series with the cap.

William A Kulze wrote:

>Back in Jan I picked up an early model(red letter) 129x and have begun a recap. Someone previously had done a partial job of it. The can electrolytic was 3 sections of 20mf, 2 at 250V and one at 25V, with a separate 8mf/250V cap for one of the 10mf sections. My question is, is having 20mf of filtering ok on this instead of the 10mf? I've heard some things of over filtering and that some issues can arise concerning charge/discharge times and in-rush current at power up. I can get the 10mf caps if I need to, but I'd like to know what problems can come up with 20mf instead.
>
>Thanks,
>Bill Kulze
>W2NVD