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Author Topic: New SB-221 build - what mods are recommended?  (Read 1068 times)
WE6C
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Posts: 18




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« Reply #15 on: November 10, 2017, 11:12:41 AM »

This is a good idea. The vacuum relay (output switch) and a reed relay (input switch) will eliminate "hot switching" and intermittent oxidized amplifier relay contacts. The W7RY board adds electronic bias regulation and switching. The board is easy to assemble, and Jim offers a suitable reed relay.
Quote
Unless QSK is needed that board and associated parts you have to buy is expensive overkill. Old stock relays slow down with age and are readily available for around $10 from Mouser, etc.
The better rigs allow TX/RX timing to be matched to the relay speed and thats good for regular 30-35 WPM + VOX type CW operation. I havent needed anything fancy in 50+ years.
The main reasons are to get rid of "hot switching" and increase reliability with hermetically-sealed relay contacts. QSK function is a side benefit. In addition to giving you adjustable electronic operating bias, the W7RY board also eliminates relay contacts for switching between operating and cutoff bias. For the spendthrift ham, a second set of reed relay contacts can be used instead. There's no need to use a Band Aid by delaying RF (and not all current and existing rigs can do that). The worst-case vacuum/reed relays toggle in about 1ms while the fastest a rig can produce RF is about 5ms.

Bryan, What would be the ballpark cost for these relays?
Bob
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K0BT
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Posts: 357




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« Reply #16 on: November 10, 2017, 01:10:59 PM »

Definitely keep drawings of anything you do.  It's disconcerting when you can't remember the details just two years later.
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KW4GT
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Posts: 72




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« Reply #17 on: November 10, 2017, 06:33:06 PM »

Definitely keep drawings of anything you do.  It's disconcerting when you can't remember the details just two years later.

Sounds like you're speaking from experience. Cool
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