Heath SB102 on 40 meters

[W5EUQ]

Kenneth has some VERY good information here.  I agree with ALL his 
procedures.  Alignment is important AND "HOW it's done" is important too. 

I use a Neutralization procedure recommended on the Heath list server 
years ago.  Can't recall how to lead you to it right off... research can 
find it....it's a good procedure. 

Alignment in the transmit instead of the receive, is also a good idea.  
I didn't realize it, but I aligned per the book and then I went back and 
aligned the coils on the transmitter to peak it up too... maybe I'm 
doing the same thing as Kenneth and didn't realize it... good idea Kenneth.

The SB's and HW's can run one "around the flag pole a couple of 
times"... I've been there and found myself wondering if I knew anything 
about RF and fixing equipment... then I would figure out that I had 
"missed the obvious"....   IF ALL ELSE FAILS, follow the Heathkit 
procedures to the tee and you will most fix the problem or get it MUCH 
closer.
  *_THEN _*go to the *_Heathkit list server_* _and research_ "*tuning 
procedures for SB and HW rigs" *and you will find _*MUCH BETTER ways to 
tune it up and the "dogs" usually come around.  *_

Good luck. 
Bob

 

Kenneth G. Gordon wrote:
> On 1 Oct 2006 at 21:55, Bernie Murphy wrote:
>
>   
>> I am at a loss to figure out why my SB102 has about 5 db loss on
>> receive and won't transmit at full power on 40 meters.
>>     
>
> In my experience with the restoration of several SB/HW transceivers, 
> this is a common problem if the alignment procedure is not followed 
> exactly.
>
> The coils associated with the driver/preselector tuned circuits are 
> connected in a series-parallel arrangement: i.e., the 80 meter coil 
> stands alone, then the coils for all other bands are connected in series, 
> then that series string is connected in parallel with the 80 meter coil.
>
> The adjustments of all those coils interact.
>
> First of all, for a correct alignment, the 80 meter coil is adjusted first, 
> then 10, then 15, then 20, and lastly 40, in that order.
>
> Secondly, the driver/preselector tuning must be set carefully to those 
> positions shown in the manual in the alignment procedure, WITH THE 
> EXCEPTION that on 40 meters, especially, the tuning of those 
> capacitors must be centered, and the VFO set for the exact center of 
> the band.
>
> Due to the design of the driver/preselector tuned circuits, there is ample 
> range, extending beyond the band edges, for every band, EXCEPT 40 
> meters. On 40 meters, there is BARELY enough range of the 
> driver/preselector control to cover the entire band.
>
> In fact, in some instances, I have favored one end of 40 over the other 
> if the operator uses one end more often than the other.
>
> Thirdly, I always align the driver/preselector coils in TRANSMIT, not 
> receive, as specified in the manual. I use a wattmeter, or, sometimes, 
> and oscilloscope connected to the antenna output jack with the rig 
> feeding a dummy load, then adjust the MIC/CW Level control for SOME 
> output, usually no more than 30 watts or so, final resonated, and adjust 
> the coils for maximum output.
>
> After having done the entire procedure once, I go back and do it, if 
> necessary, several more times to make sure everything is correct.
>
> Oh! I probably should have mentioned this first: the FIRST thing I do is 
> to neutralize the final on 80 meters, as specified in the manual, not on 
> 10 as is usual. However, I remove plate and screen voltages from the 
> final amp, use an oscilloscope on the antenna output jack, and adjust 
> the neutralizition as accurately as possible.
>
> I also set the carrier null using an oscilloscope.
>
> Lastly, I adjust the "neutralizing wire" for the driver as closely as I can 
> before starting the alignment procedure.
>
> You might also make certain that your heterodyne oscillator coils are 
> tuned to the right peak. If any of those are on the wrong peak, it can 
> badly effect output on a particular band.
>
> If the alignment is all correct, you should get 110 watts output on 80, 
> 100 watts output on all the rest, except 10, which should be at least 80 
> watts, and can be as much as 90.
>
> Good luck.
>
> Ken Gordon W7EKB
>
> -----------------------------------------------------------
> Products bought, sold or traded here is the responsibility of the
> parties involved.  This list and the City of Tempe are not responsible
> for losses or misrepresentations of any kind.  Buyer beware!
>
> -----------------------------------------------------------
> This list is a public service of the City of Tempe, Arizona
> -----------------------------------------------------------
>
> Subscription control - http://www.tempe.gov/lists/control.asp?list=HEATH
> To post - HEATH at LISTSERV.TEMPE.GOV
> Archives - http://listserv.tempe.gov/archives/HEATH.html
>
>
>   

-----------------------------------------------------------
Products bought, sold or traded here is the responsibility of the
parties involved.  This list and the City of Tempe are not responsible
for losses or misrepresentations of any kind.  Buyer beware!

-----------------------------------------------------------
This list is a public service of the City of Tempe, Arizona
-----------------------------------------------------------

Subscription control - http://www.tempe.gov/lists/control.asp?list=HEATH
To post - HEATH at LISTSERV.TEMPE.GOV
Archives - http://listserv.tempe.gov/archives/HEATH.html