[HeathKit-Radios] Help Connecting Heath SB-610 to SB-101 for recv monitor

[Dick KF4NS]

Bob et al,
Just a little tip regarding the tight slugs/cores in the typical 
boatanchor equipment that has been a lifesaver for me considering the 
tight supply of the cores.

If I notice any tightness at all during first attempt to adjust, I 
first get out my can of 100% silicone spray and shoot a short burst of 
it in there and let it set for several minutes to allow penetration 
and evaporation of the propellant, then give it a short twist of the 
tool which usually indicates a much more free movement of the core. 
Give it a try.
Good luck.

73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow!


---------------------original message--------------------
Date:    Wed, 6 Aug 2008 04:23:21 EDT
From:    Bob Burns <G3OOU at AOL.COM>
Subject: Re: [HeathKit-Radios] Help Connecting Heath SB-610 to SB-101 
for recv monitor...

Hi

I have my SB-101 on the bench at the moment doing a tidy up after 
having
spent the last several days adding 160m as an additional band (not a 
task for
the faint hearted!). My SB101 is now showing the same sensitivity  and 
RF output
figures as in the manual so the designers did a good job and  probably 
did
not expect a forty year life!

1. Putting a 1pF capacitor from the anode of V4 to ground causes the S 
meter
to reduce by about half an S point from S6 using the internal 
calibrator
signal - putting my fingers near to the hot end of this capacitor 
causes  more
reduction in signal level. This is what I would expect and the effects 
of  the
additional 1pF should be correctable by a small adjustment of the core 
in  T103.

If you are getting significant loss in sensitivity then I would check 
that
the capacitor that you are using is actually 1pF and not considerably 
larger.

The sensitivity of the SB-610 is stated to be 800mV at low frequencies 
so
you will require a reasonable amount of signal in order to see it. For 
IF
monitoring you need to carry out the changes shown in the manual and 
make sure
that both IF tuned circuits in the SB610 tune correctly. The tuned 
circuit at
the SB610 input sees the capacitance of the coax cable connecting it 
to the
SB101 so keep the coax as short as possible.

Are you using coax inside the SB101 from the 1pF to the rear panel?

2. By the way, I discovered that the cores in the SB-101 RF tuned 
circuits
can break very easily and I thought that this was due to weak cores. 
However, I
 found that the insulated hexagonal trimming tools have shrunk a 
little over
the  forty or so years and no longer fit the cores correctly, 
therefore
exerting more  stress than necessary and causing the core to break. 
The Allen key
that fits the  standard SB101 knobs can sometimes be used to move a 
jammed core
or remove a  cracked core as it appears to be a good snug fit in the 
core
center. Otherwise  you have to dig the core out with a sharp scriber 
without
damaging the coil  former.

Anyone know of a source of newly made trimming tools for Heath  cores?

73

Bob

G3OOU
G-QRP  6907
_http://members.aol.com/rfcburns_ (http://members.aol.com/rfcburns)





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