[Hammarlund] hq 145a tone chirp/blip when tapping on the table. normal?

[Richard Knoppow]

    Thank you, those numbers look familiar. I think the 6100 is a 
"five star" type. Probably either one is less microphonic than 
the prototype.
    BTW, I have two SP-600-JX one a 17, the other unknown. Both 
need work and have been on the back burner for a long time. Both 
are microphonic, one more than the other. I think this is not the 
LO but something mechanical. Since I have to do considerable 
disassembly I will investigate the turret since I think the 
problem may stem from it.
    The SP-600 is a frustrating receiver because it should be 
world class but very often isn't. I think there are a lot of them 
out there that work but are not right. Both of mine had bent 
plates on the oscillator sections of the main tuning capacitor. 
Plates should never be bent. I got a replacement for one. I think 
the plate bending is the result of the stators not being centered 
correctly. The stators are fastened with clamp screws, I think 
they may wander with time changing the capacitance vs: rotation 
law. They are relatively easy to center using feeler blades. I am 
looking for a second intact cap to replace the bent one on the 
other receiver. Lots of work to do and have too many conflicts.

On 11/8/2019 1:58 PM, Jacques Fortin wrote:
> Industrial 6C4 is the 6100, ruggedized military version is the 6135 (triple mica, etc...),  half of a 5814A.
> 
> 73, Jacques, VE2JFE
> 
>       I tried to find the industrial version of the 6C4, which is supposed to be less microphonic and can't find it.

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL