[Collins] Collins R-391

[Dr. Gerald N. Johnson]

On Tue, 2009-07-07 at 21:45 +0000, pjdobosz at juno.com wrote:
> I am trying to establish a realistic market value for a Collins R-391 receiver I currently own.  Due to the relative rarity of these receivers, there isn’t a lot of information from prior sales therefore I’m looking to this group for an opinion of the value both as is and after restoration.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
>  
> The R-391 is complete, unmodified and is in reasonably good cosmetic condition.  The receiver is operational but there is a fair amount of hum in the audio and leading me to suspect the electrolytic caps in the power supply need replacement.   The rotary switches and mechanical linkages need cleaning and lubrication but other than that everything else is in decent condition.  It is definitely an excellent candidate for restoration. 
>  
> I’m trying to decide if I keep it and restore it or try to sell it.  A lot will depend on its value before and after the restoration since my pension income now that I'm retired doesn’t give the luxury of doing too many projects of this type.  What says the group on value?
>  
> Paul – K8PD
> ____________________________________________________________
There was one sold on ebay in 2007. They don't remember it now.

A 2002 survey of prices put the range of R390A prices from 250 to 1000,
and the R391 prices from 450 to 998. I expect the motorization adds
considerably to the mechanical complexity and doesn't improve manual
operation any, so any added price is more collecting than for using.

Tubes can contribute hum, from heater to cathode leakage. That will be
60 Hz, usually sinewave (no harmonics). Hum from filter capacitors is at
120 Hz usually and has a saw tooth shape with many harmonics. Filter
capacitors that let the radio hum have on occasion exploded and released
their contents into the insides of a radio. All their contents are
conductive. Its a real pain to clean, so that's not a safe operating
condition. New can type electrolytics are getting hard to find.

Needing filter capacitors and a thorough cleaning and lubrication takes
away from the user value, but may not hurt the collector value as much.
Its not an interest of mine to have one.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer