[Heath] Heath Digest, Vol 94, Issue 7

[ChrisIwata]

Good result!

My AR-2 had the same problem with the IF cans.

Calculating the capacitance from the surface area and the width of the 
mica wafer must have been hard:  How did you do the measurements?

For those who don't have an inductance meter to measure the coils with 
the internal cap disabled,  the value for the caps is around 110pF.  It 
will be slightly different for primary vs secondary winding, and 1st vs 
2nd IF can.

You might be able to pinpoint which cap(s) is bad by wiggling each IF 
can solder lug successively.  Do this with the radio ON and an insulated 
wand.  The mica wafer is physically attached to the solder lug.  Anyway, 
that's what worked for me.  Thus, I didn't have to replace all 4 caps.

Chris, KL7DM

On 10/20/2018 1:31 PM, Al Skierkiewicz wrote:
> Guys,
> I have just finished restoring an AR-3.  It was a labor of love as I my
> first ham receiver AR-3.  I had purchased it used for $15 from George at the
> Radio TV Lab in Chicago.  I saw this one at the hamfest in Oak Creek, Wisc
> for $25 and just wanted to get it going.  My cap was not frozen but very
> stiff.  I just shot some Lubriplate white grease into the ball bearings that
> make up the reduction.  I waited for a day and just started moving the shaft
> until the grease got distributed.  Worked wonders.
> I had more problems with the fact that the kit wasn't fully correctly wired
> and that the silver mica caps in the i.f. transformers were all noisy.
> (Thunder syndrome)  If you tap on the cans and you hear tons of crackling
> and thunder, then you have the same problem.  I removed the mica wafers and
> replaced the caps with dipped silver micas.  I calculated the values from
> the area of the mica that was plated with silver.  The fact that there were
> wiring errors meant that the radio had never been aligned.  A RF signal
> generator is kind of necessary for alignment of this box.  Although I got it
> working, I also bought a Q multiplier that wouldn't work at all.  Turns out,
> that the i.f. was 50kHz low.  Once I got everything correctly tuned, the Q
> mult worked great as well.
> Al
> WB9UVJ
>
>


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