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Author Topic: Johnson Viking Matchbox Tuner 375W  (Read 1459 times)
AC0FA
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Posts: 298




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« on: August 18, 2008, 04:06:24 PM »

Hello all,
I am restoring a Johnson Viking Matchbox Tuner to its original wiring configuration.

I have a Johnson Viking II hooked to the 52 ohm
CO-AX so-239 transmitter input.

I have a Hammarlund HQ-129X connected to the
300 ohm twinleadigs cn  recever output.

I would like to use the built in relay so both rigs can share the tuner and the 450 ohm ladder line to the full wave 80 meter loop.

This newly aquired tuner has been by passed of course for transciever operation.

I was able to glance at the schematic and a few pictures on e-bay.

RECEIVER SIDE OK?
There was enough connection evidence left on the recieve side of the relay and the mention in the owners manual about an adjustable tap set for 300 ohm receive on the input coil.

I was able to listen to strong signals and throught the process of elimination clamp the tap  for the receiver (inside the tuner) to the seccond loop from the rear of the tuner on the shorter input coil that has the longer one running through it.

I am assuming this is correct especially if no one tells me it is not.
 
TRANSMITTER SIDE MISSING 1st mystery
Ok Second mystery the TRANSMITTER portion of the internal relay on the JOHNSON MATCHBOX is missing.
the wafer is broken off that had the wire and contact
attached to it.

There is no OBVIOUS evidence of a connection on the input coil near the receiver tap where I would  expect the transmitter relay to be connected.

The schematic shows (I think) the connection on the input coil L1 loop nearest the ground which would be the loop towards the front of the tuner.

I  need some help with the following because all the tuners I have seen or seen pictures of have been modified also.

I dont have the wire or the broken off piece of wafer board from the relay . I dont have a picture of
the relay in its original I can only guess.

Does the original transmitt side of the relay have a stranded insulated wire with a small screw type clamp on the end like the tap on the recieve side of the relay?

This would explain why there is no connection evidence.

COIL CUT AND EXTRA CONNECTION

The L1 coil short larger diameter coil has a chunk cut from it. Some one cut off part of the loop closest to the rear of the tuner. Starting at the 12:00 position.

It would appear from the schematics and pics that the loop ends at the 6:00 position.

I need help with this also as it is nearly impossible to verify from pics. I soldered 1/2 the loop back on and it seemed to hear ok.

EXTRA CONNECTION
It is at this 6:00 position there is a 4" long connection soldered to the long coil. It is solid wire identical to the leads used to connect the coil to switches.  

This connection goes NO WHERE all of the switch connections are accounted for.

If there is any one out there who is still using their Johnson Viking Matchbox tuner 275W in its original un-modified state or just remembers what they were like before modifing it.

I would really like to hear from you.
So I can put some power through this thing.  

I Added a SPDT open frame relay to make up for the brokem part. This little tuner is almost ready to go.      
 
Thanks for your help.

It ain't the size of the load that counts its the way you wiggle your wire!!!

   



     
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K3HVG
Member

Posts: 149




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« Reply #1 on: August 20, 2008, 02:03:54 PM »

The relay is sort of a special one.  It has 3 poles and is a larger and has wide spaced contact arms.  The third set of contacts (pole) is used to mute the receiver.  You might want to download the book from BAMA, although the book does not have any photos.  If you'd care to, drop me a line via email and maybe I can get a jpeg of the inside of the tuner. Understand that I use the KW version of these tuners.  regards K3HVG
jeepp@comcast.net
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AC0FA
Member

Posts: 298




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« Reply #2 on: August 24, 2008, 08:34:13 AM »

k3hvg,
Thanks a jpeg would really help. I spent a few hours experimenting on friday and found the sweet spot on the L1 input coil for both Tx and RX side of the relay. To be at the 9:00 to 10:00 position on the seccond loop from the rear of the tuner. This is the end of L1 that is un-grounded.

With the tuning capacitor completly un-meshed

At this position the RECEIVER, hooked to the tuner  with 450 ohm feed line through its antenna port,
Hears very well he gap titan and has the same peak as the

TRANSMITTER with 50 0hm COAX ,into a dummy, load and the matching capacitor at 15 tick marks of being meshed. I saw able to achieve a SWR of 2:1 between the VIKING II and the Matchbox
 
I  was hoping for a better match. For example the  
the matching capacitor fully un-meshed.

Is this a normal result for this combination?

With the RECEIVER tapping a second position on L1,  (directly behind the Tap for the Transmitter at the 10:00 position) There was no peak the loudness was very broad I could turn the matching capacitor
22 deg in either direction before it had any effect on the in coming signal.

I havent decided which position I like best.

I would expect having the receiver more closely peak with the transmitter would make things easier to tune.

Any thoughts?

AC0FA    
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