[Heath] Fw: SB-301 help

[Glen Zook]

I vote #1.  However, for the SB-301 and NOT the SB-101 over the SB-303 (fat fingers?).

Stability and selectivity are about the same.  Both receivers use the same i.f. filter.  After 5-minutes, or less "warm up", the SB-301 is just as stable, if not more so, than the SB-303.  Calibration on the SB-301 is usually as good as, in some cases, actually a little bit better, than the SB-303.  This is assuming that the SB-303 has the TRW version of the LMO.  If not, then the calibration of the LMO is going to be a LOT better in the SB-301.

Because of internal noise, the SB-301 is generally more sensitive than the SB-303.

Reliability:  For holding alignment, both are about the same.  For component reliability, there are certain transistors in the SB-303 (especially in the audio circuits) that are prone to failure.  However, every so often, one needs to unplug and then re-install the circuit boards because the edge connectors do become corroded and that causes problems.  Unplugging and then re-installing the circuit boards usually cleans the contact surface and eliminates connectivity problems for a year, or so.  Then the operation needs to be repeated.

For repair:  The dual gate MOSFET devices in the SB-303 are getting very difficult to locate these days and are fairly expensive when found.  One must have the fairly scarce extender cards to easily work on the SB-303, especially when aligning.  The 6AS11 tube in the SB-301 is not as common as the remainder of the tubes but is still available.  One has to be careful when repairing the SB-303 because of the possibility of "lifting" the plating from the printed circuit boards.  As for the majority of components, both use commonly available parts.

For overload:  The SB-301 wins "hands down".  The SB-303 overloads very easily on strong signals and is very difficult to use if there are other amateur radio stations nearby transmitting on the same band.  "Intermod" is basically non-existent on the SB-301 but can be a problem with the SB-303.

As for heat:  Yes, the tubes in the SB-301 do put out more heat.  However, this is usually not a concern, especially when the matching SB-401 is used with the receiver.
 
 
Glen, K9STH


Website:  http://k9sth.com


________________________________
 From: Chris Kepus <ckepus at comcast.net>
To: Heath at puck.nether.net 
Sent: Wednesday, January 2, 2013 4:05 PM
Subject: Re: [Heath] Fw:  SB-301 help
 

 
Wow! What a great response from the “Puck” group! Thank you! As I told the “Heath” group,  I appreciate every comment.  As a couple of you commented, it will be interesting to see if there is clear cut choice.
 
I hope more folks check in with their views and rationale.  
 
I will summarize all this but since I have some rather pressing matters to take care of in the next several days, it will likely have to wait until next week.
 
To assist with the compilation, it would help me greatly if you would come back to me one more time using this scheme to record your opinion/preference**:
Give me a "1" if you strongly prefer/recommend the SB-101 over the SB-303; "2"  if you slightly prefer the SB-101 over the SB-303; "3" if you would be equally happy with either; "4" if you slightly prefer the SB-303 over the SB-301; "5" if you strongly prefer the SB-303 over the SB-301.  Also, let's also simplify the main reasons for your preference. Please use these descriptions: Stability; Selectivity; Sensitivity; Ease of repair; Reliability (as in needing only infrequent under the hood repair); Energy consumption (hot vs.not); Concern over parts availability and/or cost; strong signal handling (intermod performance); Prefer Tube equipment, Prefer solid state equipment. Whew! 
 
One of the more creative recommendations was: "If you can find a SB-403, keep the SB-303"! :-)
 
**Some of you do not need to come back again as you made it real easy for me to put your preference on the scale and stated your rationale clearly.
 
Again, thanks for taking part in this opinion poll.  In the end it will help me and I'm sure many others who are on the fence. 
 
73,
Chris
W7JPG
 
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