[Boatanchors] SWEEP TUBES AND FPM 300S

[Robert Nickels]

On 1/11/2016 12:04 PM, Rob Atkinson wrote:
> they were employed in cheap poorly constructed lightweight table top
> SSB transceivers with crappy audio and drifting VFOs
Hi Rob,

Well, some of us who grew up yearning for that kind of rig still enjoy 
putting them on the air, and having fun with all kinds of radios.  
Different strokes, is all.    For example, last weekend I finally got 
around to replacing all the out-of-spec parts in my WRL Duo-Bander 84, 
which arguably was one of the lightest-weight, cheapest-designed SSB 
transceivers on the market, even though it's $159.95 selling price in 
1967 is the equivalent of over $1100 in todays money.

Leo Meyerson understood hams and the ham equipment market pretty well, 
having over 20 years of experience by that time including the famous 
Globe line of AM transmitters as well as the very popular Galaxy line of 
SSB rigs.   Like everything,  his gear was designed to a price point and 
he always tried to provide optimal performance for the buck, which is 
why he used Heising modulation in the Globe Scout line instead of more 
expensive plate modulation.     The Duo-Bander came out at a time when 
75 meter nets and  SSB mobile operation were popular, and it was 
affordable enough that a ham could justify not hauling it in and out of 
the car.  There are some clever aspects to the design too - such as the 
5.5 Mhz first IF and a VFO tuning 1.5-1.8Mhz that allowed coverage of 
both popular 75 and 40 meter phone bands with simple and inexpensive 
bandswitches. (laugh at the ganged slide-switches if you wish but having 
fought to replace worn contacts on custom rotary switches, they have 
their advantages).    The innovative two-transistor balanced modulator 
made it very easy to null the carrier.    As someone recently pointed 
out, WRL did the kind of value-engineering most hams would do in a 
homebrew project, such as simple flat panels and using transistors where 
it made sense (which is why the Duo-Bander's VFO is so stable).

Since they're a little scarce I put up a short video on the Duobander 84:

https://www.youtube.com/watch?v=GQ6woUIDJeA

Why ridicule radios that don't happen to appeal to you?   There's lots 
of options and it's all good.  Interesting industrial history lessons if 
nothing else.

73, Bob W9RAN