Author Topic: IFR repair? SPECTRUM ANALYZER ! king has died  (Read 37534 times)

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Online PA0PBZ

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Found a picture of the unit in another A8000, and it indeed looks like the input goes directly to that module, and the thing I called  the LO input is not used there too. But it looks like it is missing a module so who knows...



Oh wait.... Is this the unit you bought? ;)
« Last Edit: July 16, 2013, 07:02:25 pm by PA0PBZ »
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Offline SArepairman

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yes

that guy has to be a real crook if he bent the rf input hardline and stole a module :clap:

OH man, it better not be that silver can on the outside housing of the unit that i threw under the bed and forgot about.

but that still would not really make sense. I think its something custom made for the antenna, pics soon
« Last Edit: July 16, 2013, 07:14:40 pm by SArepairman »
 

Online PA0PBZ

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Well, there is clearly something missing and the input rigid coax seems to have had some bending.
Looks like there was some creative maintenance on this one.
Oh well, looks like you have at least $ 105.39 worth of parts there.
And... you could have told us about the missing stuff.

The silver can on the outside (bottom unit) looks interesting  :-/O

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Offline SArepairman

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I don't really see missing parts. The one missing slot is for some option, and the external thing is just some thing.

There are no screw holes to hold any additional modules besides the 12.3 MHz thing and a 75dB attenuator. And the battery is missing too.

If there was a missing modules there would be screw holes or standoffs for it. there are none.

actually there is one stand off with no screw, but there cannot be a module there because there is a coaxial connector sticking out right next to it. It would have to be a very oddly shaped module.

and of course the tracking generator is absent.
« Last Edit: July 16, 2013, 07:31:49 pm by SArepairman »
 

Online PA0PBZ

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Yeah, but what about the 2 flatcables and the mounting hole (?) just below the rigid input cable on the bottom unit?
(and the missing attenuator, and probably the LO or at least the LO cable)
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Offline SArepairman

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Yeah, but what about the 2 flatcables and the mounting hole (?) just below the rigid input cable on the bottom unit?
(and the missing attenuator, and probably the LO or at least the LO cable)

One is for the external thingamabob and the other one might be for the tracking generator.

http://s24.postimg.org/rtp7nbimc/DSC_0116.jpg
« Last Edit: July 16, 2013, 07:35:32 pm by SArepairman »
 

Online PA0PBZ

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One is for the external thingamabob and the other one might be for the tracking generator.

I admire your optimism but I don't share the feeling. There's just a too nice place for another module in the top left corner on that picture.
Maybe it's for the TG but as I said before, you are missing the input attenuator and as far as I can see also the LO.
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Offline SArepairman

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Offline SArepairman

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the diagram for the 0-75DB attenuator in the 7550 manual would be a perfect fit for the space under it.

http://s16.postimg.org/gertm0mzo/Untitled.jpg
 

Offline SArepairman

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unless of course you replace the 0-60 with the 75!  :--
 

Online PA0PBZ

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the diagram for the 0-75DB attenuator in the 7550 manual would be a perfect fit for the space under it.

http://s16.postimg.org/gertm0mzo/Untitled.jpg

Yes, that is about the place where I'd put it when designing a thing like this, and the rigid cable still looks like it was washed too hot. I'm thinking that this cable could have been the one from the LO to the mixer module, the connector you marked as a TG connection.

I assume that the last picture is the inside of the module you retrieved from under your bed? Let me see if I can say something stupid about it.
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Offline SArepairman

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is it possible there is no LO? I don't see the 5 pin connector that is shown in the picture and I don't see where it plugs in.

the whole RF mother board looks very different, alot of the ribbon cables are not installed.

and the box is the external can
« Last Edit: July 16, 2013, 08:17:50 pm by SArepairman »
 

Offline SArepairman

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I agree that someone may have stolen the attenuator but the big free spot has no external screw marks. I removed the screws for the oven osc in the back and they were screwed on extremely tight and it left a mark in the back. The spot for the screw holes for the "missing" thing is pristine.
 

Offline SArepairman

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the systems engineering of my unit is completely different.

http://s9.postimg.org/nica6witq/lo_l.jpg

I am pretty confident there was nothing where the receive IF box is, unless it was screwed in poorly at the factory.

but there were screw marks where the VCO should be, but there is only one free port in the unit, a coaxial screw on the yig assy.
« Last Edit: July 16, 2013, 08:33:19 pm by SArepairman »
 

Offline KJDS

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There's definitely something very very odd going on.

I rather suspect that it is indeed missing things, including the input attenuator.

Offline SArepairman

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does the VCO have a good reason to connect to a yig filter assy?
 

Offline SArepairman

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I don't think its remotely possible to source modules for this thing.

 :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm: :palm :palm: :palm:
 

Offline SArepairman

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but then again where the hell is the control port for the input attenuator? it does not use a 10 pin connector.
 

Offline SArepairman

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Gentlemen, we can rebuild him.
 

Offline SArepairman

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Hey I noticed that the little can on the outside is one transistor short of a happy meal.

http://s24.postimg.org/iynl320wz/Untitled.png


http://s15.postimg.org/l4sowthm1/Untitled2.png


the VCO is missing in this thing, but the housing is even kind of eerily reminiscent of the actual VCO.

any idea what that machine on the side of the box is?
« Last Edit: July 17, 2013, 03:22:06 am by SArepairman »
 

Offline SArepairman

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I think that I can hack in a aftermarket attenuator and a soon as I can figure out exactly what that external module is I can maybe make the missing part of the VCO circuit. I can maybe get something milled out.
 

Online PA0PBZ

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As far as I can see the external module is the VCO. Now to figure out how to connect the stuff and get the cables. The attenuator is not your biggest problem, you could even put an external one on the input, or if you can find out what the control signals are you can fit something else. I even have a few laying around that probably will do the job.
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Offline SArepairman

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As far as I can see the external module is the VCO. Now to figure out how to connect the stuff and get the cables. The attenuator is not your biggest problem, you could even put an external one on the input, or if you can find out what the control signals are you can fit something else. I even have a few laying around that probably will do the job.

but there are several missing transistors, the VCO schematic has more components then that.

and i want to get this thing working sooo bad i have a nice long bent antenna i found in the trash that I want to fix
 

Online PA0PBZ

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The schematic you have is not for this model, so why worry about one missing transistor?
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Offline SArepairman

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Well, because the thing looks custom made. I dont think its the same box that fits into the empty VCO slot.

The area where the VCO is missing from has three screw marks, and the external "vco' module measures 52x54mm.

If the external VCO module was placed internally then it could at most use one screw, due to the spacing of the holes and the dimensions of the box, leaving two screw marks unexplained.
 


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