[Heathkit] SB-301 Performance
jack m
oldvette at hotmail.com
Mon Feb 18 13:26:25 EST 2013
Dale, I agree with Glenn - must be something else wrong with your 301. Assuming that all het, rf and osc coils peak ON THE CORRECT (slow) SLOPE SIDE to get the negative 2.x+ volts at the test point, and assuming your re-cap produces the correct B+ and bias voltages at their source, check the RF, mixer and IF stage performance - each voltage on each applicable tube pin is an excellent start. Check for all settings on the mode switch. If one of the 3393 or 3396 sideband crystals are off appreciably, that will show up as tremendously reduced performance. If the frequency is off high, you may be able to pull it back with a padding capacitor across the crystal to save the cost of a new one. If low sensitivity, make certain that the RF Gain circuit and pot-related components are correct and original. A voltage off by perhaps 20% may lead you to a changed resistor value or other problem. (Example - my S-Meter would not zero on my 301. I pulled the 100 ohm resistor, and it read 1200 ohms; replaced it with a used 100 ohm resistor that read 115 ohms, and it's fixed.) Then check the values of coupling capacitors to ensure the original builder got it correct. Also, someone may have had a monitor or scanalyzer attached, and hooked in at the wrong place or improperly, including shorting or damaging adjacent foil lands. Personally, my vote would be for a bubba modification or repair, or some other exotic thing for a single-purpose use, such as "improved" RTTY performance or whatever. A wothwhile exercise would be to go back to the assembly instructions and verify each component's value in the order of construction. Look underside for soldered areas or repairs that look different than the rest of the kit construction, and for added coax not supplied by Heath for clues - should all be RG-174, I think. And, as always, suspect a bad contact somewhere in the bandswitch complex, or shorted coax from excessive heat. In fact, verify that the wafers have been installed correctly and are not 180 degrees out of orientation (don't ask me how I know this). Also, realize that there may be some reason that this Heathkit, if it was a "find", may have been resold because someone else did not, or could not go through the logical troubleshooting process needed to correct a problem brought on by an unexperienced kit builder at the outset. Hopefully, the problem will show itself with just basic troubleshooting. In the end, you will be unbelievably familiar with your 301, or any Heathkit for that matter, which will aid in future problem solving and tunning for peak performance. I've got an SB-303 and greatly prefer the dynamic range of the 301, myself. Sensitivity is just fine and comparable for both. I've also got three 75S-3's and a 75S-3B, like Glen, and although I do like CW, I've never seen the 400 Hz filter as a severe negative when compared to the 200 HZ filter in my 75S-3B, or even the 500 Hz filters in any of my 75S-3's. However, I do prefer the rejection capabilities and BFO control on the Collins equipment. Please post your findings for all of us to review. Jack W3RU
> From: heathkit-request at mailman.qth.net
> Subject: Heathkit Digest, Vol 109, Issue 14
> To: heathkit at mailman.qth.net
> Date: Mon, 18 Feb 2013 12:00:06 -0500
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> Today's Topics:
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> 1. performance of sb-301 (yash at aol.com)
> 2. belden 8421 (yash at aol.com)
> 3. Re: performance of sb-301 (Glen Zook)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 18 Feb 2013 10:01:42 -0500 (EST)
> From: "yash at aol.com" <yash at aol.com>
> To: heathkit at mailman.qth.net
> Subject: [Heathkit] performance of sb-301
> Message-ID: <8CFDBFFFF1A302C-6D8-30DA at webmail-d087.sysops.aol.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Just finished going thru the 301, all the usual stuff, replacing caps, out of tolerance resisters and doing a complete test equipment alignment,all came out just fine ,as per the manual. Have worked on a lot of boat anchors over the years and run a Drake 4 line ,all the time. I was very disappointed with the 301,comparing it to the drake, several swans and a ken wood ts-599. Keeping in mind that these rigs are what they are, the Heath 301 doesn't even come close, to the performance of all the others. Iam I overlooking something with the 301? Gone back and read the old reviews and writ ups in QST and the other out of print mags, all gave the 301 decent marks. I find few if any mod's for the 301 shown anywhere,please let me know of a source, about the rig. I guess I expected more from the old rig. Iam seriously wonder if its worth the trouble to go ahead and rework the 401 transmitter and put them on the air as a working set of Heath twins.
> I would sure like to hear from others concerning their results with the 300/301 receiver and as using as a twin setup.
> thanks
> dale wt4t
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 18 Feb 2013 10:46:43 -0500 (EST)
> From: "yash at aol.com" <yash at aol.com>
> To: heathkit at mailman.qth.net
> Subject: [Heathkit] belden 8421
> Message-ID: <8CFDC064896A9F4-6D8-3CFA at webmail-d087.sysops.aol.com>
> Content-Type: text/plain; charset="us-ascii"
>
> I Found a guy with 40' of belden 8421 cable the other day and bought it. Made a set of INJ and OSC cables and have the rest of the remaining cable. If any one in the group is interested in some of the cable,would be happy to cut it into the proper 38' LENGTHS and ship it out. Iam asking for 4.00 for 2, 37" sections ,mailed. Please get back if any interest.
> thanks
> dale wt4t
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 18 Feb 2013 08:04:18 -0800 (PST)
> From: Glen Zook <gzook at yahoo.com>
> To: "yash at aol.com" <yash at aol.com>, "heathkit at mailman.qth.net"
> <heathkit at mailman.qth.net>
> Subject: Re: [Heathkit] performance of sb-301
> Message-ID:
> <1361203458.65803.YahooMailNeo at web160103.mail.bf1.yahoo.com>
> Content-Type: text/plain; charset=iso-8859-1
>
> My SB-301 works fine! ?It is the second one that I have had over the years, the first one being built new in 1968. ?In late 1972, I acquired a Collins 75S-3A (considered by many to be the best of the S-Line receivers) and ran the SB-301 in parallel with the 75S-3A before deciding to go ahead and obtain the matching 32S-3 transmitter. ?This was done for about 6-weeks. ?In 9 out of 10 situations, the SB-301 performed as well as the 75S-3A. ?It was that 10th time that made me go ahead and get a 32S-3 transmitter. ?Things like rejection tuning and slightly steeper "skirts" on the SSB filter, combined with the 200 Hz CW filter instead of the 400 Hz filter in the SB-301 made the difference.
>
> I have worked on a number of Drake R-4 series receivers over the years and definitely prefer the SB-301 to those. ?There is no comparison with any of the Swan units that I have serviced. ?The SB-301 is considerably better.
>
> Presently, I use my SB-301 / SB-401 combination on 160-meters with a home brew transverter (?http://k9sth.com/uploads/transceiver_discription-1.pdf ) and with transverters for 2-meters and 222 MHz. ?On 160-meters, I find the transverter plus SB-301 combination easier to use than my Collins 75A-4.
>
> The SB-300 is not quite as good as the SB-301.
>
> Glen, K9STH
>
>
> Website: http://k9sth.com
>
>
> ________________________________
> From: "yash at aol.com" <yash at aol.com>
> To: heathkit at mailman.qth.net
> Sent: Monday, February 18, 2013 9:01 AM
> Subject: [Heathkit] performance of sb-301
>
> ? ? ? ? ? ? ? ? ? ? ? ? Just finished going thru the 301, all the usual stuff, replacing caps, out of tolerance resisters and doing a complete test equipment alignment,all came out just fine ,as per the manual. Have worked on a lot of boat anchors over the years? and run a Drake 4 line ,all the time. I was very disappointed with the 301,comparing it to the drake, several swans and a ken wood ts-599. Keeping in mind that these rigs are what they are, the Heath 301 doesn't even come close, to the performance of all the others. Iam I overlooking something with the 301? Gone back and read the old reviews and writ ups in QST and the other out of print mags, all gave the 301 decent marks. I find few if any mod's for the 301 shown anywhere,please let me know of a source, about the rig. I guess I expected more from the old rig. Iam seriously wonder if its worth the trouble to go ahead and rework the 401 transmitter and put them on the air as a
> working set of Heath twins.
> ? ? ? ? ? ? ? ? ? I would sure like to hear from others concerning their results with the 300/301 receiver and as using as a twin setup.
>
> ------------------------------
>
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