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Old 27th Mar 2021, 12:25 am   #1
Brett530
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Default Trio 9R59. First Restoration - Need Direction

For my first ever radio restoration project, I bought a used Lafayette HE-30 (Trio 9R59). Overall it is in good shape, but upon opening it, I noticed the 5Y3 rectifier tube was missing. On the under-side, I noticed someone had installed a voltage regulator (probably to improve drift). I later noticed that there were 2 diodes soldered to the bottom of the rectifier socket, I assume as a rectifier tube replacement.

A couple of questions:
1. Are 2 diodes sufficient? Back from my electronics classes, it took 4 diodes to make a full bridge rectifier.
2. What should I check before my initial power on? The radio has a 1A blown fuse in the socket, but I can't imagine that is a large enough fuse for this radio.

Thanks
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Old 27th Mar 2021, 12:48 am   #2
usradcoll1
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Default Re: Trio 9R59. First Restoration - Need Direction

Quote:
Originally Posted by Brett530 View Post
For my first ever radio restoration project, I bought a used Lafayette HE-30 (Trio 9R59). Overall it is in good shape, but upon opening it, I noticed the 5Y3 rectifier tube was missing. On the under-side, I noticed someone had installed a voltage regulator (probably to improve drift). I later noticed that there were 2 diodes soldered to the bottom of the rectifier socket, I assume as a rectifier tube replacement.

A couple of questions:
1. Are 2 diodes sufficient? Back from my electronics classes, it took 4 diodes to make a full bridge rectifier.
2. What should I check before my initial power on? The radio has a 1A blown fuse in the socket, but I can't imagine that is a large enough fuse for this radio.

Thanks
The transformer has a center tap, so two diodes are fine!
Replace the fuse and use dim lamp limiter to check the set for a over current condition. Use a 60 watt incandescent lamp.
There's plenty of information in the radio forums regarding that method to prevent further damage.
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Old 27th Mar 2021, 8:47 am   #3
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Default Re: Trio 9R59. First Restoration - Need Direction

The 5Y3 is a full-wave rectifier, not a bridge so two diodes are fine.
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Old 27th Mar 2021, 2:14 pm   #4
Andrew2
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Default Re: Trio 9R59. First Restoration - Need Direction

The 1 amp fuse should be more than enough for a receiver like this in normal operation.
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Old 28th Mar 2021, 1:04 am   #5
Brett530
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Default Re: Trio 9R59. First Restoration - Need Direction

Thanks for the feedback. I found buried in the manual that it wants a 2A fuse. I was able to power up and no sparks or smoke, just the dial lamp came on, so I'm off to a good start. Now to run some tests. I've been cleaning the case & chassis, but I'll almost be disappointed if I don't have to fix anything inside
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Old 28th Mar 2021, 6:30 pm   #6
G6Tanuki
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Default Re: Trio 9R59. First Restoration - Need Direction

There's loads of info out there on the Trio 9R-59 range of radios to help you with your restoration.

A couple of things to think about 'further down the line' -

[1] the coils in the RF box were slathered with a wax that - over time - absorbs moisture and degrades - this reduces the 'Q' of the coils to the point where the local-oscillator can stop oscillating on the highest-frequency band. Gentle directed heat from a hair-dryer, and the use of a "Q-tip" cotton-bud [appropriately named!] to wipe away the wax as it softens can really improve matters.

[2] there's a yellow wire that connects the antenna tuned-circuit to the 'Ant Trim' panel-control; this runs through the oscillator-compartment of the RF box. Stray capacitance between this wire and the oscillator tuned-circuitry can mean that - on the highest-frequency range - the "Ant Trim" control will shift the LO by quite a few KHz, which makes tuning SSB stations on 21 and 28MHz a real needs-three-hands game.

Re-routing the yellow wire to the Ant-Trim control so it's outside the RF-box really improves overall 'driveability'.

And if yours doesn't have the neon-glow regulator for the LO/BFO's HT-rail - it's really worth fitting it if you want stable reception of SSB stations.
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