Hi, BMWMAN here,

I am in the process of recapping an HQ-129-X Hammarlund Receiver and I've run into a bit of a problem. Although both the schematic and the parts list of capacitors indicate that there is only one .01MF tubular capacitor, there appears to be at least 4 of them in my receiver (if not possible 5). Am I working on a unique model, a special model, an after factory modified model, or what? Should I continue to replace the capacitors value-for-value or should I do more research regarding the model I have?

Thank you for your time and response. I sincerely appreciate it!

Sometimes manufacturers run out of a particular value and substitute another. For example, a .01 could be used in place of .0082 or .012 Can you tell us what part of the circuit they are in and their function? Perhaps post a link to the schematic? I've listened to Art Bell in the past but not too good at remote viewing.

The HQ129x parts list shows many .02mfd paper capacitors, used as bypass capacitors. Most of these could be substituted with .01mfd with no change in performance.

You would be safe, to just replace with the value presently installed.

--Chuck

Over the years bypasses went from .1 to .01 as both technology and knowledge improved. I have no problem using a .05 in place of a .1 or a .01 in place of a .05 or anything in between in sets that cover the BCB to say 30MHz and use 450-500KHz IF's

When the tuning range goes well below the BCB and/or much lower IF's are used I stay closer to the original values and do a quick capacitave reactance calculation first.

Hammarlund had a thing about using .02uF over about two decades, however Id have no problem using .01 if thats all I had available and didnt want to wait. Their design changed very little over that time also The 129X is also very prone to way out of tolerance resistors and dont forget to pull off the BFO coil cover for caps and resistors.

Carl

I want to thank all for the VERY timely responses I have received tubular regarding whether or not to replace the capacitors in an HQ-129-X receiver based of the originnal schematic/pasts list or based on the capacitors currently installed in the unit on a value-for-basis. I'll play it safe and replace the capacitors on a value-for-value basis.

Again, thank you so VERY much for your valued information!

Gordie (AKA the BMWMAN)