[Milsurplus] RBC - mods

[Peter Gottlieb]

I did plenty of mods, but almost all were related to power supplies. 


Peter

> On Jun 16, 2016, at 3:18 PM, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
> 
>> On 16 Jun 2016 at 12:31, George Babits wrote:
>> 
>> Ken,
>> 
>> I wonder what percentage of cobbled up product detectors were really an 
>> improvement?
> 
> Not only PDs, George: IMHO, most "modifications" to any of our gear.
> 
>> Maybe 10%?
> 
> That much? I think much fewer.
> 
>> I have had SX-28, R-388, R-390, Super Pros, and 
>> SP-600 receivers with prodector modifications.  All were pretty dismal. 
>> Tells me that the average modifier really didn't know what he was doing.
> 
> I have never, ever said any such thing.
> 
> I will repeat what I have said many times: the original designers of MOST of our old gear 
> were no dummies. They were highly intelligent and capable men. Some, in my opinion, were 
> sheer geniuses. Like Dr. Drake and his boys at ARC, for instance.
> 
> Even so, we HAVE learned a few things since then which CAN improve those rigs. AGCs 
> and detectors. Noise limiters too, perhaps.
> 
> But, any mods have to be properly designed and implemented for the particular rig, and 
> everything about the old rigs has to be taken into account before the soldering iron is even 
> plugged in. Some of us are STILL learning about some of the very interesting features 
> designed into the "ARC-5" receivers, for instance. WHY the designers did what they did is 
> very important to know or to figure out before someone even THINKS about "modifications".
> 
> I would venture to say that well over 90% of the usual "ham" modifications to our old gear 
> makes them work WORSE than they would if left alone.
> 
> My thoughts on "modifications" pretty much follows the medical doctor's rule, "First, do no 
> harm." Most mods do lots of harm, mainly to those features of a rig that the "mod designer" 
> never even considered.
> 
> In my almost 60 years as a ham, I can remember, at most, two modifications which actually 
> helped the associated gear, and I can't even remember now what those were.
> 
> Even so, my PD mod to my BC-779 made an immense improvement to it. Perhaps I was 
> lucky, or perhaps the original problems with it could have been handled a different way.
> 
> There were two very annoying problems with my first, almost new, BC-779: 1) the BFO 
> injection level was way, way too low. A strong CW signal would simply overwhelm it. I had to 
> ride the RF gain control constantly. And 2) it was extremely noisy. I mean internally 
> generated noise from the mixer stage and other stages was way too evident. It masked 
> weak signals. There was a constant, loud hiss from it.
> 
> My PD mod fixed both problems, making that BC-779 a real joy to use. 
> 
> I especially liked the '779's variable IF band-width feature, and the wonderful crystal filter. 
> Hammarlund's crystal filter design was WAY ahead of everyone else's at the time. After my 
> experiences with that receiver, my respect for Hammarlund went way up.
> 
> Ken W7EKB
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