[R-390] R390-A Contract Choices.

[Bob Camp]

Hi

To answer the second part of your question.

The 47 pf cap is there to take care of the inductance of the chassis 
mount cap that is on the cathode. Apparently they found that some of 
the parts were not low enough impedance at the high end of the band. 
Fixing the problem isn't quite as easy as it looks. You want to be sure 
you don't create a parallel resonant circuit between the two caps. 
Normal advice on bypass caps is not to worry to much about values as 
long as they are higher than what is specified. This is one place where 
the normal advice doesn't apply ..

	Take Care

		Bob Camp
		KB8TQ


On Mar 28, 2005, at 11:04 PM, Flowertime01 at wmconnect.com wrote:

> In a message dated 3/28/05 3:05:48 PM Eastern Standard Time, 
> K4HCA at alltel.net
> writes:
>
> I have been looking for an R-390A for last few months. Question; 
> Apparently,
> these fine receivers were manufactured by several (?) different 
> companies.
>> From those of you who have had experience with them, are receivers 
>> manufactured
> by one particular company more desirable as a restoration project than
> another? Or, put more simply, if one had a choice, which one would you 
> recommend?
>
> Many thanks,
>
> Harold
>
> __________________
>
> Back when (68-75) we had the receivers by the hundreds. We considered 
> them
> all equal. They were all alike inside and out side. There were 
> differences (wire
> harness, cosmo PTO). Some gear trains ran better than others but any 
> and all
> receivers would work to specifications.
>
> We did not go out of our way to swap modules around but it did happen. 
> If you
> get one that mostly matches inside, you make consider buying some 
> lottery
> tickets. Fair Radio is selling working receiver for $600.00.
>
> Watch the meters. Some receivers had glow in the dark paint on the 
> meter
> face. Some tree huggers though us fellows would be licking the paint 
> on our meter
> faces or throwing R390/A in the land fill. Many receivers had the 
> meters
> pulled before they went to salvage sale. The cost of replacement 
> meters with
> "acceptable" interior paint can drive the cost of a receiver up.
>
> The state of the tube set can increase the price. Consider what it is 
> going
> to cost to replace a set of tubes.
>
> The next real cost is the work that has been done on the receiver. A 
> simple
> semi annual preventive maintenance cleaning and alignment performed by 
> a
> skilled technician takes a minimum of 4 hours. Plan to spend all day 
> Saturday twice
> a year doing a cleaning, tube check and alignment on your receiver. 
> Skilled
> electronic techs are billing $20.00 $25.00 an hour for independent 
> time. More if
> they are supporting a commercial shop overhead. A real gear cleaning, 
> panel
> paint job, recap, audio deck rebuild (different cap values for better 
> audio
> sound) or other real repair can push the price of a receiver up over 
> the 1,000
> mark real easy.
>
> The 3 K item was a real stretch.
>
> Real deals are still being found real regular. Start shopping and do 
> not pass
> over any because of the perceived contract it come from. If its all 
> there it
> can be returned to full function. Some real care and it can out 
> perform the
> generic run. Super smooth gears trains are very doable. Better audio 
> through
> some audio deck changes. Better sensitivity through tube selection 
> (not a lasting
> change as tubes age). Better performance through some cap and resistor
> changes.
>
> You may have to pay for work that has already been done. You can do the
> needed work your self. There are several of us fellows on the 
> reflector here who
> will do work for you. Mostly you will select a local fellow to you as 
> UPS can be
> done but it cost. Crates and freight service is a pain to arrange and 
> also
> cost.
>
> You may already have an offer or two from the list for a receiver.
>
> Let us know what you find. Let us know what problems you find in the 
> receiver.
>
> Happy Operating
>
> Roger KC6TRU
>
>
>
>
>
>
>
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