Newbie with an 800B

[Day Radebaugh]

Hello:

I'm Day Radebaugh from El Dorado, Kansas, and was happy to find this site.  30 years ago, when I was a starving student, I lived in a house in Baltimore that was in the process of being sold.  They had an old Scott console (with a phonograph, as i recall) which i bought for $5.  I couldn't keep the cabinet, but kept all but the phonograph.  It's been stored inside ever since.

So now I'd like to have it restored, and I would build a new console to contain it.  Do you have any suggestions about how to proceed?  Anyone you know of who could tackle a functional restoration of this unit?

Thanks for your help.

Day Radebaugh

[Day Radebaugh]

I take a coax off my outside TV antenna for FM.  AM is a Tecsun tunable loop:https://www.ebay.com/i/270432895082?chn=ps

I'm out on a farm 60 mi outside of Wichita, and get good reception.

[Doug Smith]

On the KT66's, have a look at The Tube Store's site https://www.thetubestore.com/kt66-tube-review .   Originals are now very scarce and pricey, as you probably know.    Depending on the vendor, current KT66's draw 1.3A or more heater current, whereas the original 6L6GC's are at about 900 mA heater current.    You might want to monitor the transformer temperature, to see that it doesn't overheat, and the heater voltage line remains at about 6.3V +/- 10%.

[Day Radebaugh]

Doug:

Thanks very much.  Are you suggesting that I would not have compatibility issues with original Kt66's, or that I should monitor these voltages and currents in any case?

[Dave]

Actually the voltages under operation are about the same. Definitely not taxing to the tranny. I’ve been running 66s a few times a week about 9hrs for the past 15 years. If you want to step it up there’s the obscure Russian 6N3C which I use in the Scott and MC 30s.... best definition of the bunch. The coax driver in the 800 is arguably well into the 90dB range for efficiency, hardly taxing at any volume.

[Doug Smith]

With this kind of substitution, I'd monitor these voltages and currents, because a burned out transformer is expensive.    I measured a B.V.A. KT66 (UK mfg. early 60's) and it came out at 1.28A at 6.3VDC, right on nominal current.  This is likely typical of what you will find.   The existing tube lineup should pull about 6A excluding the 6L6's, 8A including them, and will need to supply 800 mA more with the KT66's.    It should be able to take the extra current, so proceed while verifying the transformer temperature is more-or-less same as before.   If you have the equipment and interest, you could measure the output distortion vs. output power at several output levels, to see if the KT66's are doing anything measurable.   OF course, there is a lot of subjectivity in the way it sounds.

Day Radebaugh said:

Doug:

Thanks very much.  Are you suggesting that I would not have compatibility issues with original Kt66's, or that I should monitor these voltages and currents in any case?

[Day Radebaugh]

From my read of the tube spex on https://www.thetubestore.com/kt66-tube-review, it appears that the Tung-Sol KT66 is a pretty close match to the 6L6G's.  I went searching for the 6N3C's, and they appear to be a rare bird, available in ebay maybe or Ham fests.  My instinct tells me to go with the Tung-Sols.  

[Dave]

Yes the 6n3cs belong on a good tube amp stereo.... very refined musicality over the more hifi 6l6. Can’t go wrong w Tungs, run them all nite, that 800 tranny is just idling along

[Day Radebaugh]

Many thanks.  Ready to pull the trigger on this one, and I will monitor temps on that tranny, and let you know.  

[Bob Bell]

Hmmm ... I live in Oakland and we have cable TV. For radio I really only listen to FM, as AM appears to feature only zealots of differing shades, be they of religious, political or sports bent. I have several old loops lying around from the backs of old radios. Nevertheless, when I hook up one of the latter I get nothing on AM. Not even a crackle. Same with FM, but perhaps that is because I just have the coaxial cable looped over a pipe in my basement shop.

I have the big thick manual, and on Page 8 (fig 6) it suggests placing a 50mmf cap between the AM and FM connection and running a doublet antenna for AM and FM. The two wires of the doublet are connected to the two AM connections - one being the connection that already has there 50mmf cap connected to. What is a doublet? Just two wires? The ground is shown connected to earth - a water pipe in this case.

Fig 7 on the next page shows the same 50mmf cap in the same place, the same earth ground plus the first FM and the first AM terminals are also connected to the ground while a single wire goes from the second AM terminal to either an outside antenna or a loop. 

As I mentioned in an earlier post, I have a coaxial wire coming from the first FM-IF tower. It's about ten feet long and is draped along a pipe under the ceiling. Do you think this is doing anything at all?

My gut feeling is that my lack of any reception at all is not Ariel related, but something else. Nevertheless, it seems sensible to get a decent Ariel in situ before investigating further. 

Any suggestions or comments?

Day Radebaugh said:

I take a coax off my outside TV antenna for FM.  AM is a Tecsun tunable loop:https://www.ebay.com/i/270432895082?chn=ps

I'm out on a farm 60 mi outside of Wichita, and get good reception.

[Day Radebaugh]

Bob:

My first approach here would be to narrow the problem down to either aerial or radio.  I'd hook up a basic FM dipole to the FM leads and see if you get anything out of the radio.  Do you have an old Radio Shack FM dipole around?  They're basically everywhere and will get you a signal if there is one.  I'd be very surprised if you don't have a good FM station in Oakland.

Doublets are well documented on the 'Net; see https://www.electronics-notes.com/articles/antennas-propagation/dip...

[Day Radebaugh]

Bob:

My first approach here would be to narrow the problem down to either aerial or radio.  I'd hook up a basic FM dipole to the FM leads and see if you get anything out of the radio.  Do you have an old Radio Shack FM dipole around?  They're basically everywhere and will get you a signal if there is one.  I'd be very surprised if you don't have a good FM station in Oakland.

Doublets are well documented on the 'Net; see https://www.electronics-notes.com/articles/antennas-propagation/dip...

[Day Radebaugh]

Ordered my TungSol KT-66's.  I'll let you know how they sound.  This radio kicks butt as it is, but this should be interesting.