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 Post subject: Re; zenith transoceanic G500 SW reception issues.....
PostPosted: Dec Thu 07, 2017 4:38 am 
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Joined: Nov Sun 11, 2007 5:26 am
Posts: 89
Location: bc canada
I've had this one for a while,recently put it back into use. BC. band reception great all through the band.S.W. is having some issues,few quite faint signals,no wwv,which comes in quite well on my other sw receivers at any given time.Adding a longwire,oddly enough quietens it down,& no reception improvement.Swapped out 1L6 with another.Contacts have all been cleaned,caps resistors replaced as needed.Tele. antenna connections good.Any ideas??


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 Post subject: Re: Re; zenith transoceanic G500 SW reception issues.....
PostPosted: Dec Thu 07, 2017 7:53 am 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 3618
Location: Near Brandon, Iowa
Each SW band is tuned to the Waverod (collapsible mast) antenna as part of the alignment procedure. So attaching a longwire antenna would slightly detune the set.

The 1L6 tube can affect reception but so can the RF and IF amp tubes, and the detector diode. All of these tubes should be tested for emission. If the set still has a selenium rectifier, check it for reduced voltage output- this can drastically impair shortwave-frequency operation of the set.

Leaky/open coupling or bypass caps can also cause degraded performance of the set. If it still has any factory underchassis caps, replacement of them would probably enhance its operation.

Has the set been aligned recently?


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 Post subject: Re: Re; zenith transoceanic G500 SW reception issues.....
PostPosted: Dec Thu 07, 2017 9:41 pm 
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Joined: Sep Sat 27, 2014 4:24 am
Posts: 1375
Location: Oxford, MI
Check your filament voltage. The tubes in this set can be finicky about operating at SW frequencies if the voltage is too low. 1.45V on the 1L6 is what you want to aim for. Also an alignment may be helpful as previously stated.

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 Post subject: Re: Re; zenith transoceanic G500 SW reception issues.....
PostPosted: Dec Thu 07, 2017 9:59 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 359
Location: Manchester, NH
I have same issue with a 8G005 - It seemed to align well - caps have all been replaced - voltage of the filaments set - I am starting to believe the tubes may be poor at best. I can get a couple of stations on each band but very weak -- yet broadcast band is great -- will follow this thread to see suggestions -- thanks for starting it


Griz


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 Post subject: Re: Re; zenith transoceanic G500 SW reception issues.....
PostPosted: Dec Thu 07, 2017 10:11 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11543
Location: S. Dartmouth MA 02748-1225 USA
Use a 7-pin tube adapter to extend the tube connections on the 1L6 socket connect. Carefully measure the filament voltage, it should be as specified for the tube type.

Check all, other individual filament voltages as well as the overall voltage supplied from the filament power source.

What I have found is carbon resistors that shunt the filaments have dramatically changed in value and there will be too low a filament voltage to properly operate the 1L6 and/or other tubes. There will be a shift in bias too. To measure bias a high resistance meter must be used 10 or more megohms input. As long as the B+ and filament voltages are correct, with good tubes and caps the radio should perform normally.

Chas


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 Post subject: Re: Re; zenith transoceanic G500 SW reception issues.....
PostPosted: Dec Mon 11, 2017 7:12 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4941
Location: La Porte, IN, USA
This may seem obvious, but SW reception generally has been terrible for several years, due to the solar minimum, and with fewere and fewer powerful international broadcasters on the air, the bands have often seemed "Dead" much of the time. Have you made a sisde by side comparison with a good, modern SW receiver?

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