New Browning Mark IV Build

[mark4]

;)My latest project. New browning Mark IV.
New chassis and IF board and to many items to mention.
Receiver board under side of chassis.

[Sandbagger]

Jun 18, 2009 16:42:09 GMT -5 mark4 said:

My latest project. New browning Mark IV.
New chassis and IF board and to many items to mention.
Receiver board under side of chassis.

That's a cool project. I know you've mentioned before that you've built up MkIV's from parts. So I'm curious to know how/where you found these surplus parts. I'd love to take on a project like that. I haven't built a complete tube radio in probably 30 years now, and it would make a cool project, especially considering the pedigree of the radio.

[mark4]

I purchased somethings years ago from Macom.
A guy in Canada.
And other places for years. I stocked up on parts for years.
I came across NOS boards & chassis and a Case fo a IVA. Got lucky.
Barkett also has many parts.
This is not cheap to do by any means!
And a extreme amount of work! Ugraded many parts on the boards before I ever installed them. Notice the upgraded 600V high temp wiring used on the Jones jack.

[Sandbagger]

Jun 19, 2009 15:57:55 GMT -5 mark4 said:

I purchased somethings years ago from Macom.
A guy in Canada.
And other places for years. I stocked up on parts for years.
I came NOS boards chassis and Case! For a IVA. Got lucky.
Barkett also has many parts.
This is not cheap to do by any means!
And a extreme amount of work! Ugraded many parts on the boards before I ever installed them. Notice the upgraded 600V high temp wiring used on the Jones jack.

Yea, I figured it wouldn't be cheap, unless you fell into a good deal somewhere. It's probably cheaper to teardown and rebuild than to build from scratch......

[mark4]

Rebuild is what I did in the past.
A heck of allot less work.
But new chassis look awesome.
Just so much work when your starting from bare bones.
I would look at it and think where should I start.
After weeks of work it starts to comes together.
First I upgrade the boards and then start the wiring on the chassis.

[mark]

Oh My God! I built a Mark IVA from about 4-5 junkers about 10 years ago. I even bought new faceplates when they were available in the fully silkscreened adhesive type. When I was done it was a real gem but... What a pile of work that was! Not to mention the pile of left over parts from the other units. I sold the set for 750.00 back in about 1999 I think.

[Deleted]

Mark4,

I forgot to ask. My friend (a collector), has a Mark IV, and he wants a ping put in like the Mask III. Is this possible? I am working on his Cobra 2000 meter problem right now.

[mark4]

Absolutely. This circuit is the same in the Mark IV/IVA that produces the ping. C243 if the 2uf 450V capacitor is on the board. Some earlier versions had 2 capacitors in the underside of the chassis. One for SSB and one for AM. C7 for AM and C12 for SSB that were wired to the receiver mode switch.

[Deleted]

I have two 2uf 450V caps underneath on the receiver. Change both of these to like a 68uf value?

[2600]

One of those capacitors is active on AM only, and the other one on SSB only.

Just wire your larger cap across the one wired to the AM side of the mode selector. No need to remove the old cap if it's still good.

Adding a switch to turn off the new capacitor should be placed in the GROUND side of the new cap, not the 'hot' side. If you don't leave the 2uf part in place, the quality of the receiver's speaker audio will suffer if there is NO capacitor in the circuit at all. That 2uf part needs to be there unless the larger cap is wired to be active full-time.

73