[Heath] SB-100 TX audio gain question

[Mark V Johnson]

Pretty much every SB series, or HW series for that matter, piece of Heath gear I’ve ever owned is the same: the mic gain control is pretty close to  max. As per the manual, check you ALC level; assuming the ALC circuit is working OK,  keep the mic level around “6” on the meter on voice peaks. Also, when tuning up in tune mode, you’ll notice the output level rises so far and then there is no further output increase as the gain control is increased. That’s the level you need, when there is no further increase. I use a Heath EV mic: HDP-21 on my  SB-100 and the HDP-21a on my HW-101. 

 

I also use a D-104 on occasion and have to juggle the gain of the in-board pre-amp and the Heath Mic gain control to prevent overdriving. The SB-610 scope helps. 

 

I just finished doing a re-furb on an SB-100. Works great but needed a heck of a lot of work to get it back in shape. 

 

Mark VE3LU

 

 

From: Heath [mailto:heath-bounces at puck.nether.net] On Behalf Of Alexander N. Gerli
Sent: Sunday, December 27, 2015 3:02 PM
To: heath at puck.nether.net
Cc: heathkit at mailman.qth.net
Subject: [Heath] SB-100 TX audio gain question

 

Hi, Folks!

My SB-100 is working fine, with one little exception: to have any TX audio out, I need to have the MIC/CW Level set virtually max. Checked the output waveform on my SB-610 scope, and it appears clean. The tubes in the mic audio chain are good, so I'm not certain what may be up. Seems as if the level should be optimal around 50% or a little greater, but not maxed out.

Anyone have a suggestion where I might start looking?



​73,​

 

​Sandy AC1Y​



Alexander N. Gerli, Sr.

548 Allred Mill Road

Mount Airy, NC 27030-2202

Scotsmen walk about 900 miles each year.

A Scotsman drinks around 45 gallons of Whisky a year.

Scotsmen get about 20 Miles Per Gallon.

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