[Heathkit] SB-630 information 2nd request - problem discovered!

Wed Dec 8 19:47:11 EST 2010

This site has the #3AGB neon lamp listed for sale:

http://www.normanlamps.com/index.php/cPath/82_241/sort/2a/page/1

-Don Spoon-
K0APK

On 12/8/2010 6:26 PM, Tom Chesek wrote:
> The 1984 Heath Master Parts lists shows the 412-34 as follows:  62.0 V, .40 MA, #3AGB
>
> Tom K3TVC
>
>
>
> From: jack m
> Sent: Wednesday, December 08, 2010 5:13 PM
> To: tchesek at epix.net ; mike.mccarty at sbcglobal.net ; heathkit at mailman.qth.net
> Subject: RE: [Heathkit] SB-630 information 2nd request - problem discovered!
>
> Hi Tom and the rest of the group,
>
> I did get a copy of the SB-630 Monitor parts page from a list member.
>
> The number for the SB-630 neon light is 412-34.  Description is simply, "Neon lamp".  Perhaps someone has access to the Heath Master Parts List which would spec this component and cross-ref it to a familiar GE GLow Lamp or other type.
>
> I could not find the part referenced on the "regular" parts links commonly available to us.
>
> The SB-620 parts list at least stated the lamp used in that kit was the NE-83, in addition to the "Neon Lamp" description.
>
> Thanks to all who have helped so far.  I may attempt to expose a piece of the broken lead if all else fails - (never filed glass before).
>
> Jack  W3RU
>
>> From: tchesek at epix.net
>> To: oldvette at hotmail.com; mike.mccarty at sbcglobal.net; heathkit at mailman.qth.net
>> Subject: Re: [Heathkit] SB-630 information 2nd request - problem discovered!
>> Date: Tue, 7 Dec 2010 18:56:44 -0500
>>
>> Does the SB-630 manual give a Heath part number and if so what is it?
>>
>> Tom K3TVC
>>
>>
>>
>> -----Original Message-----
>> From: jack m
>> Sent: Tuesday, December 07, 2010 6:33 PM
>> To: mike.mccarty at sbcglobal.net ; heathkit at mailman.qth.net
>> Subject: Re: [Heathkit] SB-630 information 2nd request - problem discovered!
>>
>>
>> Hi Mike,
>>
>> This certainly is a comprehensive analysis you have described to the list.
>>
>> I received a parts list from a list member which has added to our resources.
>>
>> I took a closer look at the bad bulb, and I discovered that the "GE-A6" I
>> claimed earlier is actually a "GE-AG", which ties in with your findings from
>> the Glow Lamp data book. Now, for which AG, there may be a clue with the
>> color of the dot(s). Looking very critically at the dot(s) complex using
>> greater magnification, it "resembles" the appearance of a Venn diagram, with
>> what may have been three color dots originally daubed on the glass.
>>
>> The (most obscurred) one on the lower left of the triad is either black or
>> green (probably black if I had to guess), the one on the lower right has
>> only an outline remaining of what was most likely brown, and the one on top
>> is probably red. Looking inside of both the NE-2 and the AG, there is no
>> obvious appearance of doping on either element.
>>
>> I sure wish I could do surgery, but the one lead is broken off up in the
>> base.
>>
>> I checked the part numbers in the SB-610 and SB-620 manuals, and the
>> (similar) neon lamps for each of these kits are completely different,
>> although the SB-620 lists it's two neon lamps as NE-83's in the description.
>> No description for either the SB610 or SB-630 lamps - just Heath part
>> numbers. A check of the usual Heath parts sites has nothing listed for neon
>> lamps in the 412-series of part numbers.
>>
>> This is turning into a real detective story!
>>
>> All help is greatly appreciated. What a resource this reflector is!
>>
>> Regards,
>>
>> Jack W3RU
>>
>>> Date: Tue, 7 Dec 2010 14:26:33 -0600
>>> From: Mike.McCarty at sbcglobal.net
>>> To: oldvette at hotmail.com; heathkit at mailman.qth.net
>>> Subject: Re: [Heathkit] SB-630 information 2nd request - problem
>>> discovered!
>>>
>>> jack m wrote:
>>>
>>> [...]
>>>
>>>> So I figure this is NOT an NE-2 in the SB-630. With the NE-2, the
>>>> ID/buzzer just goes on and stays there, but can be released with a
>>>> plastic tool prying up on the relay. Without the NE-2, the reset
>>>> button will pulse the relay on/off.
>>>>
>>>> Upon magnified inspection, I see a "GE-A6" cast into the broken
>>>> bulb's base, whereas I see a "GE" and "2" on my ten neon spares.
>>> I've got a copy of the GE Miniature Lamp catalogue, and it doesn't
>>> list a GE-A6. So, I pulled my copy of the GE Glow Lamp book, and
>>> looked in the specs section, and there is no GE-A6. It gives
>>> both the "old" and "new" designations.
>>>
>>>> Just a copy of the parts list would be very helpful, as well as any
>>>> insight to the neon bulb used in the relay circuit. Any pages from
>>>> 29 on back would also be appreciated. Many thanks to those who have
>>>> helped so far.
>>> It's probably not going to be helpful. It'll probably just
>>> say it's a selected neon bulb with a dot.
>>>
>>> Let's look at the circuit and try to figure out what it does.
>>>
>>> C23 and C24 start out discharged, and the lamp is off. The
>>> caps charge up through the 144 Meg resistance until the voltage
>>> across the lamp is sufficient to make it fire. The sudden
>>> flow of current causes the voltage at C22 to jump, and this
>>> gets passed along to the tube grid, pushing it into conduction,
>>> and energizing the relay.
>>>
>>> When the relay pulls in, the charge on C23 and C24 gets dumped
>>> to ground through current limiter R28, with a time constant of
>>> 4 ms, that is, nearly instantly. It would be about 20 ms to
>>> complete discharge. At that time, the voltage is mostly
>>> from the 220K R33, hence only about 1/2 % of the
>>> voltage on the pot. At this time, the voltage from the pot
>>> through the 220K resistor must be less than the maintaining
>>> voltage of the lamp.
>>>
>>> So, the lamp is part of a relaxation oscillator. It's probably
>>> a selected one, with a known breakdown voltage and resistant
>>> to "dark effect", possibly with a coat to imcrease leakage
>>> resistance (it's in a 140Meg circuit, after all).
>>>
>>> The 0A2 regulates somewhere between 140 to 168 V. That means
>>> that the range of voltages on the pot are
>>>
>>> Vreg. Range on pot Across Bulb
>>> ------ ------------ -----------
>>> 140V 54.6 to 57.4 V 82.6 to 85.4 V
>>> 168V 65.5 to 68.9 V 99.1 to 102.5 V
>>>
>>> So, we need a bulb which is pre aged and has some radioactive
>>> material for stable operating characteristics, and likely
>>> a coat for low leakage. It must be able to fire reliably
>>> on less than 82.6 V, and must extinguish reliably when
>>> the pot voltage is applied through 220K. The latter requirement
>>> is a little harder to figure, since the supply has an
>>> impedance I haven't figured, but is something on the
>>> order of 90K. We'll just look for lamps with an extinguishing
>>> voltage close to the maximum strike voltage (reduced operating
>>> range).
>>>
>>> Looking in the GE glow lamps, I find these as candidates
>>>
>>> Initial Dark BV
>>> --------------- Extinguishing
>>> Bulb Min Max Voltage (250K)
>>> ---- --- --- --------------
>>> 3AD 65 80 50 edgy high BV, good candidate
>>> 3AG-A 60 80 50 edgy high BV, good candidate
>>> 3AG-B 65 73 50 sel. 3AG-A, excellent candidate
>>> 3AG-C 68 76 50 not as good as 3AG-B
>>> 5AB-A 60 80 50 cheapest preaged, good candidate
>>> 5AB-B 62 72 50 selected 5AB-A, excellent candidate and low cost
>>> 5AB-C 68 78 50 selected 5AB-A, excellent candidate
>>> 5AG 64 80 50 good candidate
>>> 5AG-A 68 76 50 excellent candidate
>>>
>>> My best guess is that for the lowest cost most likely to
>>> succeed lamp, try the 5AB-B, if you can find one. Next best
>>> is probably the 3AG-B. Anyway, this table should get you
>>> in the ballpark for a lamp which will work.
>>>
>>> Try not to handle coated bulbs very much. Oils etc. from
>>> your hands may compromise the leakage resistance.
>>>
>>> HTH
>>>
>>> CC: original poster
>>>
>>> Mike
>>> -- 
>>> p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
>>> Oppose globalization and One World Governments like the UN.
>>> This message made from 100% recycled bits.
>>> You have found the bank of Larn.
>>> I speak only for myself, and I am unanimous in that!
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