[Hallicrafters] SX-117 disaster

Tue Aug 2 02:41:03 EDT 2016

    Check R-64 and R-63 for value.  This is a voltage divider from the 
B+ that sets the voltage at pin-2. I don't know how this relates to the 
RF being burned but worth checking.  Its possible the AVC is partly 
shorted due to a fried cap in the RF but this is pretty removed from there.

On 8/1/2016 7:58 PM, Jeff wrote:
> Doing some voltage checks this evening, and interesting observations.
>
> I'm leading towards the AVC, as I'm not getting much fluctuation on the
> S-meter (meter movement seems OK...).   DC Voltage checks on all of the
> tubes show very close to the manual specs, with the exception of V10B,
> Pin 2.  My manual indicates that the voltage there should be 24 volts,
> and I am seeing 4.
>
> Any thoughts?
>
>
>
> On 7/31/2016 11:47 PM, Richard Knoppow wrote:
>>    Well, the cap is easy enough to check, a VOM will tell you if its
>> shorted and depending on the value may give you a kick if its OK.  My
>> guess is that its OK.
>>
>> On 7/31/2016 7:44 PM, K9FFK wrote:
>>> Jeff:
>>>
>>> C4 is also a suspect. Its a 300V mica.
>>>
>>> If it is shorted, AVC goes to ground through L5 along with V1's
>>> bias...red plates.
>>>
>>> If it is open, no signal. V1 is normal. Receiver is deaf.
>>>
>>> Dick, K9FFK
>>>
>>>
>>> On 7/31/2016 7:26 PM, Jeff wrote:
>>>> Thanks to all the fast responses.  I've drowned my grief a bit, and I
>>>> did some disassembly.  The Antenna coil surely does look like it got
>>>> toasted.  I've included an image on my webserver:
>>>>
>>>>
>>>> http://www.podengo.com/sx117/L5.jpg
>>>>
>>>>
>>>> In looking at it, it looks as if the coil form actually deformed
>>>> (inside) so that the slug won't move past a certain point.  I don't
>>>> see any damage to rotary switches or other components.  The 6DC6s test
>>>> OK, but I don't have any replacements in my stock to try a different
>>>> one.
>>>>
>>>> Anyone have any advice on the coil (or a spare you can part with?)
>>>>
>>>>
>>>> Jeff
>>>>
>>>>
>>>>
>>>> On 7/31/2016 3:05 PM, Jeff wrote:
>>>>> Looking for some advice or consolation...
>>>>>
>>>>> Previously well working SX-117/HT-44 twins.  I hadn't run them in a
>>>>> long time, and many cables got messed with in the mean time.
>>>>> Unfortunately, in my haste to hook the pair back up again, I got the
>>>>> transmitter output fed into the receiver antenna input... and then
>>>>> hit transmit to tune up the transmitter...
>>>>>
>>>>> It's taken me a while to stop cursing about it, but now my SX-117 is
>>>>> deaf as a post.  A quick check of the RF amp and 1st mixer show that
>>>>> the tubes are OK.  A signal generator on 14.250 is barely audible,
>>>>> but I can no longer get a good strong peak on the preselector.  I can
>>>>> get a bit more of a peak on 40 meters, but it's still quite deaf.  I
>>>>> had the rigs in 20 meters when the mishap occurred.
>>>>>
>>>>> It's just about acting like there's no antenna at all hooked to it.
>>>>> I get no increase in noise whether or not it's hooked to the antenna
>>>>> or dummy load.
>>>>>
>>>>>
>>>>> I've had the courage to admit I've done something heroically stupid
>>>>> -- so I'm reaching out to the list for any thoughts or guidance as to
>>>>> how to fix this.
>>>>>
>>>>>
>>>>> Jeff
>>>>>
>>>>>
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>
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL