[Boatanchors] Comarison?

[Carl]

----- Original Message ----- 
From: "Drew P." <drewrailleur807 at yahoo.com>
To: <boatanchors at mailman.qth.net>
Sent: Saturday, December 19, 2009 12:42 AM
Subject: Re: [Boatanchors] Comarison?


> On his receiver design, Carl wrote:
>
>>...a double tuned manually controlled preselector. Saves trying to find 
>>the right components to get it all to track. I hate drive belts, gears and 
>>all that mechanical crap.
>
> I like the way the mechanicals look and operate in the R-390A.  That sort 
> of arrangement would be a nightmare for a home constructor to implement, 
> however.


But its a lot simpler than the non A version.


 If you don't mind a little carefully managed non-signal path silicon, how 
about an encoder on the PTO/LMO shaft feeding a microcontroller feeding a 
stepper motor to tune the front end?  Tracking is just a matter of tweaking 
values entered into a lookup table.


Im limiting my silicon to 2 terminal devices.


>
>>Beam deflection mixers are vintage history and the only good one is 
>>getting real pricey.
>
> So, what is so bad about the beam deflection tubes intended for color tv 
> demodulator service versus the 7360?  Yes, the price of a 7360 is going 
> stratospheric.  The 6ME8 and its ilk are cheap and abundant. That alone 
> makes their use tempting.


Ive no personal experience with the alternatives but from what Ive read only 
the 6JH8 holds promise. However a dual triode is simpler to implement and 
the Pullen has a performance edge. The 7360's I stuffed in my 75A4 in 65 can 
still hold their own with anything BUT all BDM's appear to age and unbalance 
fairly rapidly. Luckily I stashed away several NIB 7360's when they were 
considered worthless; that A4 still gets used a lot.


>
>>The lowest distortion audio that you can build ending up with PP 6V6's at 
>>a minimum.
>
> What, no 2A3?  C'mon, ya gotta have a little audiophoolery!


Oh, I have plenty of those and other audiophool tubes NIB. However its more 
fun to stick them on Ebay a few at a time and watch the feeding frenzy. Its 
better than a 401K by far.


>
>>Bells and whistles:  Output for a digital readout...
>
> That digital readout must, of course, use Nixies, or maybe even Decatrons, 
> whose low upper frequency limit would be accommodated by use of some 
> bizarre variant on a multi-modulus counter.  Mercury delay lines and 
> Williamson tubes!  Bearskins and stone knives!


Next you will expect a Wunderlich detector!


>
> Kidding aside, I like the sound of your design and the expertise you lend 
> to this forum, Carl.


Thanks Drew. It comes from playing with this stuff since the 50's in labs 
and at home and doing a lot of reading. The "ancients" did all the hard work 
and I havent pattened any circuits yet (-;

Carl


> Drew
>
>
>
>
>
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