[Heath] Heath Digest, Vol 94, Issue 10

Wed Oct 24 17:46:27 EDT 2018

You can still make the IF cans look as "original".  Although the IF 
coils might be at high voltage, the voltage across each coil is much 
smaller.  You could use 50 volt NP0 ceramic disc caps: These are only 
5mm in diameter and will easily fit inside the can.  Just keep the body 
of the cap away from the aluminum shell (which is grounded) on the 
primary (plate) winding side.  The secondary (grid) winding is at low 
voltage anyway.

I'd be wary of using the JW Miller cans. Their mounting looks different, 
they don't use the brass clip.

As for me, I placed the replacement caps externally.  My AR-2 had 
already seen many mods once I decided it was unusable (by today's 
standards) above 40 meters as built from the manual.  My mentality for 
equipment is to make it work better, not necessarily to retain as original.

Chris, KL7DM

On 10/23/2018 8:07 PM, Al Skierkiewicz wrote:
> Chris,
> I forgot to add that I found the thunder quite by accident.  After a quick
> initial alignment to at least hear WGN AM (their tower is under 10 miles as
> the crow flies) I was still looking over things with the radio on.  I went
> away for a few minutes and when I came back the gain was way down.
> Suspecting a cold solder joint, I took my screwdriver, turned it around so
> that I was holding the blade and then started tapping.  When I accidently
> hit the i.f. can, there was a lot of thunder and then the gain came back.  I
> then tapped on the other can and got more thunder and changing gain.  That
> began the long road to opening the can when I couldn't find solder issues.
> That prompted an internet search and then a long road to figuring out what
> to do.  A good friend of mine, former work buddy, always recommended that
> when restoring gear, I should make as few changes to the original as
> possible.  I had some silver paint and I thought I might use that, but then
> closer inspection showed that some silver had actually migrated to the edges
> of the mica and there were stains on the insulator base.  My choice at that
> point would be to wire in caps external.  But my buddy Bob's voice kept
> whispering in my head that I should only make a change internal to the can
> so that the radio would remain as stock as possible.
> Bob sent me this link as a possible JW Miller substitute for the cans...
> https://www.surplussales.com/Inductors/Ind-SmAdjRF/Ind-SmAdjRF-1.html
>
> I did not record the manufacture data on the coils but I did a search and
> found the coil numbers in a data sheet.  If anyone opens a i.f. can for this
> radio, please post the manufacturer part number.  I believe it is on the
> insulated base.
> Al
>
>
> -----Original Message-----
> From: Heath [mailto:heath-bounces at puck.nether.net] On Behalf Of
> heath-request at puck.nether.net
> Sent: Monday, October 22, 2018 11:00 AM
> To: heath at puck.nether.net
> Subject: Heath Digest, Vol 94, Issue 10
>
> Send Heath mailing list submissions to
> 	heath at puck.nether.net
>
> To subscribe or unsubscribe via the World Wide Web, visit
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> When replying, please edit your Subject line so it is more specific than
> "Re: Contents of Heath digest..."
>
>
> Today's Topics:
>
>     1. Re: Heath Digest, Vol 94, Issue 9 (Al Skierkiewicz)
>     2. Re: Heath Digest, Vol 94, Issue 9 (ChrisIwata)
>     3. Mistake in my question to lists (John King)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 21 Oct 2018 11:55:15 -0500
> From: "Al Skierkiewicz" <markaren1 at att.net>
> To: <heath at puck.nether.net>
> Subject: Re: [Heath] Heath Digest, Vol 94, Issue 9
> Message-ID: <001d01d4695e$d75a5210$860ef630$@net>
> Content-Type: text/plain;	charset="us-ascii"
>
> Chris, both of the i.f. cans in the AR3 are the same part number.  To
> calculate the capacitance, I simply measured the dimensions of the screened
> silver areas, subtracting for the circular area and then pulled out the
> reference books on calculating capacitance based on the thickness of the
> mica sheet.  I calculated the larger area to be 0.086238 in.sq. and the
> smaller to be 0.0689 in.sq.
> >From the Handbook C (pf)=.224((dielectric constant x area)/spacing
>> between
> plates)  I chose 5.4 for the dielectric constant of mica and using a
> calipers, I measured the thickness of the sheet at 0.001 in.  So C=.224((5.4
> x .08638)/.001)=104.3pf for the larger cap and substituting 0.0689 I
> calculated 83pf for the smaller cap.
> Al
>
>
>
> -----Original Message-----
> From: Heath [mailto:heath-bounces at puck.nether.net] On Behalf Of
> heath-request at puck.nether.net
> Sent: Sunday, October 21, 2018 11:00 AM
> To: heath at puck.nether.net
> Subject: Heath Digest, Vol 94, Issue 9
>
> Send Heath mailing list submissions to
> 	heath at puck.nether.net
>
> To subscribe or unsubscribe via the World Wide Web, visit
> 	https://puck.nether.net/mailman/listinfo/heath
> or, via email, send a message with subject or body 'help' to
> 	heath-request at puck.nether.net
>
> You can reach the person managing the list at
> 	heath-owner at puck.nether.net
>
> When replying, please edit your Subject line so it is more specific than
> "Re: Contents of Heath digest..."
>
>
> Today's Topics:
>
>     1. Re: Heath Digest, Vol 94, Issue 7 (ChrisIwata)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 20 Oct 2018 17:36:46 -0700
> From: ChrisIwata <chrisiwata at aol.com>
> To: heath at puck.nether.net
> Subject: Re: [Heath] Heath Digest, Vol 94, Issue 7
> Message-ID: <5BCBCA1E.60807 at aol.com>
> Content-Type: text/plain; charset=windows-1252; format=flowed
>
>
> 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
>>
>>
>
> ---
> This email has been checked for viruses by AVG.
> http://www.avg.com
>
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> Heath mailing list
> Heath at puck.nether.net
> https://puck.nether.net/mailman/listinfo/heath
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>
> ------------------------------
>
> End of Heath Digest, Vol 94, Issue 9
> ************************************
>
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 21 Oct 2018 13:12:39 -0700
> From: ChrisIwata <chrisiwata at aol.com>
> To: heath at puck.nether.net
> Subject: Re: [Heath] Heath Digest, Vol 94, Issue 9
> Message-ID: <5BCCDDB7.5030804 at aol.com>
> Content-Type: text/plain; charset=windows-1252; format=flowed
>
>
> Wow, you came in pretty close.  I'm guessing, the hardest part for accuracy
> was to measure the thickness of the wafer.
>
> The IF cans on the AR-2 have different part numbers (52-4 & 52-5), but they
> are pretty much the same.
>
> Chris, KL7DM
>
> On 10/21/2018 9:55 AM, Al Skierkiewicz wrote:
>> Chris, both of the i.f. cans in the AR3 are the same part number.  To
>> calculate the capacitance, I simply measured the dimensions of the
>> screened silver areas, subtracting for the circular area and then
>> pulled out the reference books on calculating capacitance based on the
>> thickness of the mica sheet.  I calculated the larger area to be
>> 0.086238 in.sq. and the smaller to be 0.0689 in.sq.
>>   From the Handbook C (pf)=.224((dielectric constant x area)/spacing
>> between
>> plates)  I chose 5.4 for the dielectric constant of mica and using a
>> calipers, I measured the thickness of the sheet at 0.001 in.  So
>> C=.224((5.4 x .08638)/.001)=104.3pf for the larger cap and
>> substituting 0.0689 I calculated 83pf for the smaller cap.
>> Al
>>
>>
>>
>> -----Original Message-----
>> From: Heath [mailto:heath-bounces at puck.nether.net] On Behalf Of
>> heath-request at puck.nether.net
>> Sent: Sunday, October 21, 2018 11:00 AM To:heath at puck.nether.net
>> Subject: Heath Digest, Vol 94, Issue 9
>>
>> Send Heath mailing list submissions to
>> 	heath at puck.nether.net
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> 	https://puck.nether.net/mailman/listinfo/heath
>> or, via email, send a message with subject or body 'help' to
>> 	heath-request at puck.nether.net
>>
>> You can reach the person managing the list at
>> 	heath-owner at puck.nether.net
>>
>> When replying, please edit your Subject line so it is more specific
>> than
>> "Re: Contents of Heath digest..."
>>
>>
>> Today's Topics:
>>
>>      1. Re: Heath Digest, Vol 94, Issue 7 (ChrisIwata)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Sat, 20 Oct 2018 17:36:46 -0700
>> From: ChrisIwata<chrisiwata at aol.com>
>> To:heath at puck.nether.net
>> Subject: Re: [Heath] Heath Digest, Vol 94, Issue 7
>> Message-ID:<5BCBCA1E.60807 at aol.com>
>> Content-Type: text/plain; charset=windows-1252; format=flowed
>>
>>
>> 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
>>>
>>>
>> ---
>> This email has been checked for viruses by AVG.
>> http://www.avg.com
>>
>>
>>
>> ------------------------------
>>
>> Subject: Digest Footer
>>
>> _______________________________________________
>> Heath mailing list
>> Heath at puck.nether.net
>> https://puck.nether.net/mailman/listinfo/heath
>>
>>
>> ------------------------------
>>
>> End of Heath Digest, Vol 94, Issue 9
>> ************************************
>>
>> _______________________________________________
>> Heath mailing list
>> Heath at puck.nether.net
>> https://puck.nether.net/mailman/listinfo/heath
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>
>