[R-390] SRR-11/12/13 receiver question...

[Kenneth G. Gordon]

> I just bought one of those SRR recievers - before I find out the hard way,
> how does serving the radio suck? Is it the soldered-in tubes? Or are there
> more horrors?
> 
> Dave Goncalves

Hello, Dave:

I am not sure which SRR receivers Ed is talking about, but I have 
found the SRR-11/12/13 series to be very EASY to work on, 
especially when compared to an SP-600 or R-390(*). Everything is 
so heavily modularized that there is nothing to removing those to 
work on them. The only thing left in the case when the all modules 
are removed is the tuning mechanism and the tuning capacitor.

Also, someone mentioned instability. Again, I have not yet seen 
this either. Putting a tuning wand down in along side the 
connections to the tuning capacitor might make it move frequency, 
but those places are so far away from any adjustment you might 
make that I can't see why you would do this unless it was just to 
see if you could. The oscillators are either stabilized or crystal 
controlled and appear to be pretty stable so far.

By unscrewing two or three captive screws, the covers on top or 
bottom are easily removed, and one can easily connect scope 
leads, and measure voltages since all the tubes are upside down 
and very easily gotten to. You don't have to remove ANY modules 
to check ANY circuit voltage or resistance.

I have 23 of the various models of the receiver and find them fun 
to work on when compared to others. They seem to have been 
designed for service, yet need very little of it.

Further, the receivers use Sprague glass-sealed capacitors, and I 
have yet to find one that is bad. Unlike many receivers in which the 
first thing you do is replace all the paper and some of the mica 
caps, with these receivers, you put that problem way down on your 
list.

The special service cable isn't really needed since it is very easy to 
simply remove the filter-back-plane. In addition, the manual states 
that for certain tests you can't use the test cable anyway since its 
length introduces errors.

Lastly, concerning the RF , mixer and osc coils, although that is a 
(very minor) problem, the coils I have seen so far are NOT epoxy 
enclosed and on Josh Rovero's site 
(http://www.roveroresearch.com) there is a discussion and photos 
of someone who rewound one or two of the coils in his rig, so it isn't 
all that hard to do if you need to.

His site also has info on how to fairly easily make those 
problematic switch crank arms if you ever need to.

Ken Gordon W7EKB