[Hallicrafters] A SX-28 followed me home today

[jeremy-ca]

----- Original Message ----- 
From: "Julian Bunn" <Julian.Bunn at caltech.edu>
To: "jeremy-ca" <km1h at jeremy.mv.com>
Cc: <hallicrafters at mailman.qth.net>
Sent: Friday, September 21, 2007 3:40 PM
Subject: Re: [Hallicrafters] A SX-28 followed me home today


> Excellent purchase!
>
> The extra pages of calculations and schematics sound especially
> interesting ... perhaps you'll be able to scan them and make them
> available if they are of general interest?


Will do if they make some sense and arent idle doodles!



>
> One serious problem I have with the SX-28 is its weight. The thing
> is incredibly heavy.


I had to carry it down 2 flights of stairs, into the car trunk and reverse 
the procedure at home! I'm 66 but work out daily so it was just some good 
exercise.


Just moving it around on the bench is a struggle,
> let alone carrying it any distance. The risks of bending or crushing
> parts, when you have the chassis out of the cabinet, is considerable.


Part of my business is repairing HF amplifiers of similar heft plus I have a 
R-390A. A real boat anchor feels like one!


>
> I'm seriously considering picking up an old Tek scope cart just for the
> SX28 :-)


I cleaned out a cal lab some years ago and sold off a bunch of those carts 
for that purpose.

It would be fairly simple to build a rotisserie that could be used for bench 
work. They are a popular item for auto restorations.

I wonder if anyone has upgraded the RF coils to high Q toroids? Only the top 
2 bands would benefit from a lower noise figure. I might have to do some 
doodling of my own once I get into it.

---------
One hour later

I just took a break and started going thru the notes. Also read the specs in 
the manual. Im not impressed by the published audio response and apparently 
neither was a prior owner. It appears that he made changes to improve the 
high frquency response for BC or SWL'ing; there is no ham call mentioned and 
the last owner wasnt a ham either. Some doodles are marked 1968 and others 
1987 including references to a lot of recapping. Im going to make some 
circuit comparisons with the SX-42 and SX-62 audio after I get it functional 
as is (if it needs it).

Carl
KM1H
National Radio 1963-69
Service Tech
Service Manager
Engr Tech



>
> Julian
>
> jeremy-ca wrote:
>> I guess that my comment yesterday that I hadnt found a SX-28 brought me
>> good luck.
>>
>> Just before going to bed I did a quick Ebay scan of Hallicrafters and
>> there it was. A BIN of $280 and about 8 miles from me. An email, and
>> subsequent phone call got it for $180 along with original 28 and 28A
>> manuals plus original update notes for the 28. He also thru in the S-27
>> parts radio and some other non ham manuals.
>>
>> SN is H151347 which appears to put it around mid 1942. Panel, cabinet,
>> and original knobs are all excellent. Interior is somewhat rusty (mainly
>> the condensor cover)which is typical for this area. Mods noticed are a
>> SS plug in for the rectifier and a 6DJ8 plug in for the 6SC7 audio
>> driver. The manual schematic has several notes as well as loose leaf
>> pages with calculations, schematics, etc. I havent taken the bottom off
>> nor checked tube designations except for the front end which appears
>> correct.
>>
>> The seller only had it for a few days and told me that he was told it
>> was in use until 3-4 years ago. It does have a generic 3 wire cord and
>> molded plug. No other external mods, holes, etc which is a big surprise.
>>
>> Ive already bookmarked several web pages including Julians. Any
>> additional advice, comments, etc will be appreciated. For now its going
>> on the shelf until I finish a few other projects.
>>
>> This makes a SX-28 and SX-62 in one week and Im going to look at a $100
>> SX-115 tommorow. The deals are still out there and even on Ebay.
>>
>> Carl
>> KM1H
>>
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>


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