[time-nuts] General Technology Corp model 304b

Donald Henderickx wa9ylp at sandprairie.net
Mon Apr 30 00:41:21 UTC 2012


On 4/29/2012 6:27 PM, Ed Palmer wrote:
> Yes, there's a partial copy of the manual online.  It's missing a few 
> schematics, but is otherwise complete.
>
> http://sundry.i2phd.com/ServiceManual_304b.pdf
>
> Ed
>
The bottom pin is not chassis ground,on this unit.

The foam looked original before in crumbled.

The 400v cap in the ignitor circuit dumps into the primary of a 
autotransformer, from the spark I observed I would i would guess 10kv> 
so I do not think intimate contact is necessary

You asked about lamp voltage test point not lamp heater test point,that 
is what confused me. I will check it when I power it back up.

>
> On 4/29/2012 5:18 PM, paul swed wrote:
>> Curious is the manual online?
>> Would be interesting to look at.
>>
>> On Sun, Apr 29, 2012 at 6:33 PM, Ed Palmer<ed_palmer at sasktel.net>  
>> wrote:
>>
>>> Hi Don,
>>>
>>> On 4/29/2012 2:54 PM, Donald Henderickx wrote:
>>>
>>>> On 4/29/2012 1:36 PM, Ed Palmer wrote:
>>>>
>>>> Thank you Ed,Paul,and Marco for the reply's
>>>> The foam I was referring to is or was around ceramic base  were the
>>>> igniter wire goes . Yes my wire also broke loose however I do not 
>>>> want to
>>>> disassemble any more than I have to. I think that just inserting it 
>>>> back in
>>>> to the hole and securing in some way should work. I do not know 
>>>> what the
>>>> potential is but I have seen a spark jump at least an eight of an 
>>>> inch.
>>>>
>>> The igniter wire has to be connected to the base of the lamp.  The 
>>> patent
>>> explains it quite well.  Just inserting it into the hole in the 
>>> ceramic is
>>> unlikely to work.  I don't know what the voltage is, but the 
>>> capacitor that
>>> stores the voltage is rated for 400V.
>>>
>>> Does the foam look original?  It definitely isn't on mine so I 
>>> wasn't sure
>>> if it was supposed to be there or not.  The patent describes how the 
>>> base
>>> is the coolest part of the bulb.  I don't know if a foam covering is
>>> appropriate.
>>>
>>>   Tell me about the lamp voltage test point. My manual has no 
>>> mention of
>>>> it? Were is it located?
>>>>
>>> All the test points are described on page 5-3 of the manual.  The lamp
>>> heater test point is the sixth one from the top.  Ground is the seventh
>>> point.
>>>
>>>   In you first posting I think you mentioned some grounding 
>>> problems. On
>>>> this unit there is a three pin amp connector on the rear on mine 
>>>> the bottom
>>>> pin -20 must be grounded or the unit will not work. The red light 
>>>> will come
>>>> on very bright but nothing else works.I believe you can also ground 
>>>> the +20
>>>>   this allows this to work in various ground polarity systems IE telco
>>>> systems +ground. Perhaps I am wrong.
>>>>
>>> Do you mean the 3 pin round connector on the back?  That's for an 
>>> external
>>> DC power supply.  It has no other function and grounding the bottom pin
>>> (which is ground) shouldn't make any difference.
>>>
>>> Ed
>>>
>>>
>>>   I have Hp113,Hp115 that caution you on the ground polarity of the 
>>> systems
>>>> you are installing them in. I think all the -20 floats from chassis 
>>>> ground
>>>> until they get to that rear plug.
>>>> Thanks for foam an fiberglass suggestions.
>>>>
>>>>> Hi Don,
>>>>>
>>>>> You know that we're going to be swapping many emails, don't you? :-)
>>>>>
>>>>> On 4/29/2012 11:16 AM, Donald Henderickx wrote:
>>>>>
>>>>>> After following Ed Palmer's thread on 304b restoration,I was 
>>>>>> inspired
>>>>>> to get my GTC (tracor) 304b ser#279 going.  It seems that the 
>>>>>> failure of
>>>>>> this unit was the break down of the foam that was wrapped around 
>>>>>> the vcxo
>>>>>> located inside the control box. The vapors or the moisture the foam
>>>>>> collected corroded the steel fasteners and caused the switches to 
>>>>>> become
>>>>>> intermittent.
>>>>>>
>>>>> The foam around my OCXO is still in great shape.  Still spongy and
>>>>> providing lots of holding force for the OCXO.  My unit is serial 
>>>>> #449.
>>>>>
>>>>>   The replacement of the foam in the control box is not that much 
>>>>> of a
>>>>>> problem,what I need help with is what to use around the Rb lamp 
>>>>>> base. The
>>>>>> foam has turned to powder.
>>>>>>
>>>>> Do you mean foam around the back end of the lamp where the wire lead
>>>>> comes out or the foam that surrounds the reflector (#16 in the 
>>>>> picture in
>>>>> the patent that describes the lamp (3311775))?  My #16 foam is 
>>>>> really solid.
>>>>>
>>>>>   Should I try Home foam sealant? The cell's ,of this seem about 
>>>>> the same
>>>>>> as the old foam.Will it take the heat?Should I make a fiberglass 
>>>>>> cocoon to
>>>>>> put around the lamp base.
>>>>>>
>>>>> Read the fine print on the can.  It may list the maximum temperature
>>>>> rating.  I'd try a fiberglass cocoon first just because it's easily
>>>>> reversible if it doesn't work.  When your unit is running is the 
>>>>> lamp test
>>>>> point voltage correct?
>>>>>
>>>>> Ed
>>>>>
>>>>>   The unit now achieves lock in about an hour. The only other 
>>>>> thing I did
>>>>>> was to replace the caps in the main supply.
>>>>>> Any thoughts on the insulation?
>>>>>> Don H
>
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