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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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14th Dec 2022, 3:58 pm | #1 |
Octode
Join Date: Jan 2014
Location: Oban, Scotland, UK.
Posts: 1,129
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Slightly offset IF cans
I'm considering experimenting with a 4-tube station design (73 magazine, August 1971) which principle image rejection is based on the use of a 1.7MHz IF.
I've heard of a 1.6MHz IF (Denco did a range I believe) and presume such IF's will readily tune (even if a padding capacitor is required) to 1.7MHz but I ponder the original use of 1.7MHz in the first place - I mean, is this an IF that has a history of 'normal' use? It's not as if I've ever seen that frequency in second-hand sales or even seen it in any domestic/commercial stuff. Maybe my world is limited in that respect? The construction article makes no special mention of the 1.7MHz IF - as if it was something used every day - which I somehow doubt. |
14th Dec 2022, 4:04 pm | #2 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Re: Slightly offset IF cans
The US AM broadcast-band is 535-1605 kHz.
So there's a risk that using a 1.6MHz IF could get IF breakthrough. 1.7MHz IF avoids it.
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14th Dec 2022, 4:43 pm | #3 |
Octode
Join Date: Jul 2018
Location: Worthing, West Sussex, UK.
Posts: 1,002
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Re: Slightly offset IF cans
The US AM broadcast-band is 535-1605 kHz.
So there's a risk that using a 1.6MHz IF could get IF breakthrough. 1.7MHz IF avoids it. In recent-ish times the US band has been extended up to 1.7 MHz for lower power broadcasters, they should not be a problem in the UK or Europe though. Here is more on the stations on the "X" band https://mediumwave.info/2020/10/10/am-x-band-stations/ There are are, however stations on 1710 kHz in Norway and Sweden I have just noticed http://www.mwlist.org/mwlist_quick_a...rea=1&kHz=1710 There is also 1701 kHz Portugal, and maybe many more. A comprehensive list is here. http://www.mwlist.org/mwlist_quick_and_easy.php
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