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 Post subject: Zenith Royal 300 project...
PostPosted: May Fri 20, 2022 4:19 am 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7644
Location: Indianapolis, IN
Hello All,

This Zenith Royal 300 is from the group of seven radios purchased recently from another ARF member. Had never seen one in person and even though not seriously desired, thought it would be a neat addition to the Zenith Royal transistor sub-collection.

It had a small chip on top of cabinet front and needed a couple hours of careful cleaning of battery compartment before power-up. It worked at lower volume with original electrolytics. Completely disassembled and detail-cleaned cosmetics---turned out very well other than fine scratches from handling on aluminum escutcheon. Was surprised to find a tiny phillips flat-head screw at top of cabinet front used to secure the escutcheon. There are small molded "feet" on back of cabinet so it could be laid flat without scuffing the cover.

While replacing the electrolytics, noticed that the tuning cap mounting bracket was very loose. Appeared that the solder had cracked around the rivets, so carefully resoldered and all was fine. When complete, worked great with very good performance and sound quality after a "quicky" alignment by ear, but after a couple minutes it began to "crackle & pop" causing shifts in signal level. Thought perhaps an antenna rod wire had been pinched, so turned off, loosened PCB mounting hardware, and checked. When back together noise was gone, but sensitivity was also down---need to investigate further when time allows ! Possibly a failed transistor and thankfully these are socketed...

This is one of many Zenith radios of that time period that used the same basic chassis as the well-proven Royal 500...

Project pictures below---please "click" on images for larger view !

John


Attachments:
01ARF 300 PRTS1 5-19-22.jpg
01ARF 300 PRTS1 5-19-22.jpg [ 941.2 KiB | Viewed 738 times ]
02ARF 300 PRTS2 5-19-22.jpg
02ARF 300 PRTS2 5-19-22.jpg [ 706.43 KiB | Viewed 738 times ]
03ARF 300 CMPLT INS 5-19-22.jpg
03ARF 300 CMPLT INS 5-19-22.jpg [ 927.5 KiB | Viewed 738 times ]
04ARF 300 CMPLT RT 5-19-22.jpg
04ARF 300 CMPLT RT 5-19-22.jpg [ 444.23 KiB | Viewed 738 times ]
05ARF 300 CMPLT LFT 5-19-22.jpg
05ARF 300 CMPLT LFT 5-19-22.jpg [ 461.28 KiB | Viewed 738 times ]
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 Post subject: Re: Zenith Royal 300 project...
PostPosted: May Fri 20, 2022 4:33 am 
Member

Joined: Feb Fri 01, 2019 10:35 pm
Posts: 825
Location: Riverside Ca. 92504
Location: Riverside, Ca
That is a nice 300. I was lucky with mine and only had to replace the 3 mfd. attached to the volume pot. Like all that line they play loud and strong. They look a little odder than the regular radios with there volume and tuning controls. I got a black Zenith royal 700. I will post some pics of the black and brown one in the future. Tom


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 Post subject: Re: Zenith Royal 300 project...
PostPosted: May Mon 23, 2022 11:22 pm 
Member

Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7644
Location: Indianapolis, IN
Thanks Tom. You might want to replace the other electrolytics, also. It will probably sound even better as the emitter-bypass cap for the audio driver transistor has usually degraded as has the AGC filter. Found this out awhile back as I've also taken the easy route with the audio coupling caps in the distant past. Be sure to post pictures of your 700's and other projects...

Got this radio repaired today !

Tried to recreate the erratic noises heard previously and discovered when I pressed on the ferrite-bar antenna, reception would crackle and cut out. Pulled chassis and a couple of the antenna leads were laid over each other and "waxed" on the edge of fish-paper support next to the metal tab used to support the escutcheon. Could see where they had contacted this tab. Gently pulled antenna wiring free of wax and relocated away from any possible harm, then re-flowed the wax carefully with soldering tip.

While apart, I also decided to attempt re-glue of broken right-side lower chassis support boss. Cleaned both surfaces thoroughly with isopropyl alcohol and applied Superglue gel to cabinet location. Pressed boss into position and held until glue set. Let it cure awhile before reassembly and all seems fine !

Gave radio a careful alignment (which it needed) and all is well---performs & sounds like it should !

John


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 Post subject: Re: Zenith Royal 300 project...
PostPosted: May Fri 27, 2022 11:03 pm 
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Joined: Nov Wed 14, 2007 10:37 pm
Posts: 1513
Nice! Mine looks identical except the dial only goes to 1400 kc.


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 Post subject: Re: Zenith Royal 300 project...
PostPosted: May Fri 27, 2022 11:15 pm 
Member

Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7644
Location: Indianapolis, IN
Metzman---does your control panel say "ALL TRANSISTOR" at the top also ? Saw that some of the early sets had "SEVEN TRANSISTOR" instead and wondered if they were the ones with the "14" at high end of tuning knob...

John


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 Post subject: Re: Zenith Royal 300 project...
PostPosted: May Sat 28, 2022 11:50 pm 
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Joined: Aug Sat 16, 2014 1:19 am
Posts: 2303
Location: Palos Verdes, CA
John - How does the Zenith 300 compare to an early Zenith 500? - Mark


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 Post subject: Re: Zenith Royal 300 project...
PostPosted: May Sun 29, 2022 12:02 am 
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Joined: Oct Mon 26, 2009 9:02 pm
Posts: 7644
Location: Indianapolis, IN
Hello Mark---pretty much identical since circuit/components are basically the same. The tone is a bit different, though, due to the hard-plastic front cover. The back is nylon like the 500 other than the molded feet for laying it flat on a surface.

John


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 Post subject: Re: Zenith Royal 300 project...
PostPosted: May Sun 29, 2022 1:42 am 
Member

Joined: Nov Wed 14, 2007 10:37 pm
Posts: 1513
Quote:
Metzman---does your control panel say "ALL TRANSISTOR" at the top also ? Saw that some of the early sets had "SEVEN TRANSISTOR" instead and wondered if they were the ones with the "14" at high end of tuning knob...


Yes, this one says "SEVEN TRANSISTORS". Also no vernier tuning. Performance doesn't seem to be on par with the 200 series zeniths, but sound quality is very good.


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