From: Winfield Hill
Subject: Re: Limitations of the BC337
Date: 18 Jan 2003 11:43:57 -0800
Organization: Rowland Institute
X-Newsreader: Direct Read News 4.20
Mike Monett wrote...
> Winfield Hill wrote:
>> Mike Monett wrote...
>>> Do you remember Cam Searle at MIT? He would walk into the
>>> lecture and pull a ball of circuitry from his coat pocket.
>>> He would flatten it out and show everyone it was a 3
>>> transistor amplifier with feedback, built directly over
>>> the schematic. I forget the gain, perhaps 30 dB or so.
>>> The amazing thing it was flat to 100 MHz!
>>> This was in 1968. Transistors were not very good in those days:)
>> Hey you two wags, transistors _were_ pretty good by that time!
>> For example, the 2n2222 suggested in this thread as an improvement
>> over the BC337 had already been available for what, 5 years?
>> (One of my friends was involved in its design.) And many other
>> better transistors were available for RF designs. For example,
>> remember the 2n918, 1300MHz typ at 4mA - 10V, and 1.25pF at 10V?
>> I used the 2n918 in 1965 and it was an old part then, IIRC.
> This brings back memories. Of course you are right. The 2N918 was
> a pretty hot transistor.
>> I'm sure we can come up with a design matching Dr Searle's circuit
>> using parts from that era. Let's see, three transistors, 30dB and
>> 100MHz? Hmm, probably a enhanced variant on a shunt-series pair...
>> - Win
> I was kind of hoping you would say that. I'd like to see what a
> PRB941 could do, and figure out how to get a healthy signal into
> 50 ohms without burning up.
> IIRC, the feedback resistor required a small cap in parallel for
> compensation. This might get tricky at the higher bandwidths.
Mike, let's not drop this subject. We'll use a new title for the rest
of this thread, Prof Searle's 100MHz 30dB 1968-era 3-trannie amplifier