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 Post subject: Royal 7000 "mid-production" design change??
PostPosted: Oct Sun 07, 2018 10:23 pm 
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Joined: Aug Thu 23, 2018 1:11 pm
Posts: 13
I have joined the army of folks asking the question "which 'flavor' of Royal 7000 do I have??". Can someone familiar with these radios please answer a few questions?

I have an early Royal 7000, no dash number suffix. According to the sticker on the battery cover it is chassis number 18ZT40Z3. What appears to be a date code is stamped on the chassis: 8-78658. Does this indicate an August 1978 build date and, if so, is this date consistent with an early production (no dash number) design?

Here is my issue, the radio has a plug-in loopstick and the broadcast band antenna tank has a loading coil similar to the design used in the TO 3000-1, but neither of these features appear in the Zenith service manual which purports to cover both the Royal 7000 and the 7000-1 variants. Can someone please point me to the applicable manual.

The issue I am having with the radio is it becomes very noisy at a particular setting of the tuning capacitor, and only on one of the shortwave bands (SW 2 at approximately 3.9 MHz). A search of past posts revealed one similar "case", but with no resolution. The fact that it only occurs on one band rules out shorted plates or bad sliding contacts on the tuning capacitor. Placing my hand close to the loopstick makes the noise worse, which is puzzling since both the LW and BC windings should be shorted by the band switch. But then, that assumes that the schematic I am working from actually represents this particular radio!!

Suggestions for where I could find the "correct" documentation, or a mechanism behind the noise would be greatly appreciated.

Thanks to all,

Johnt46


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 Post subject: Re: Royal 7000 "mid-production" design change??
PostPosted: Nov Mon 05, 2018 12:55 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 6130
Location: Black Hills, SD 57745
I think there's a prior thread on this topic a few months back here in the Transistor Radio subforum. About how to tell which version from which.

I'm pretty sure on the 3000 the rod antenna is active along with the whip on the lower SW band. But to me, excessive hand capacitance usually points to an alignment issue, bad parts in those circuits, perhaps prior user alterations of adjusting coils, chokes or moving critical wiring layouts. And it could still be dirt on the tuning cap bearings/wipers or crud between plates.

The 7000 is a different beast which I've never owned, so I can't comment with any hands-on experience or study of it. In those cases, I give it my best baleful stare. :lol:
-Ed


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 Post subject: Re: Royal 7000 "mid-production" design change??
PostPosted: Nov Mon 05, 2018 4:21 am 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 5735
Location: Mountains of Mourne. Ireland.
Padgett Peterson's archived web-pages.
viewtopic.php?p=2872572#p2872572

Nostalgia air - Transoceanic resource library.
This archived page June 8 2012 works for all downloads.
https://web.archive.org/web/20120608163404/http://www.transoceanic.nostalgiaair.org/

Greg.

viewtopic.php?p=1801908#p1801908
more→ https://www.google.com/search?q=18ZT40Z ... radios.com


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 Post subject: Re: Royal 7000 "mid-production" design change??
PostPosted: Nov Tue 06, 2018 8:31 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 13196
Dry bearings/ground contact for moving slicer in tuning cap can cause noise at certain settings.

_________________
Tom


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