[Milsurplus] R-1004/GRC-109 restoration and other info.

[Ken Gordon]

On 1 Dec 2024 at 10:14, Matt P wrote:

> 
> After seeing a few R-1004s go up for sale on the auction site, I
> thought I'd take a closer look at my own to see what kind of condition
> it is in. This is one of the lot that I picked up from the Fair Radio
> final auction, so don't want to try putting power to in without a full
> set of tests. Just performing the basic resistance tests from Figure
> 28 in the manual, I don't get anywhere near the listed 15 Megohms on
> the B+ and signal lines, more like 1 Megohm at best. I suspect those
> little black Aerovox caps (0.03 MFD, 400 VDC) that are all over the
> place are the culprits. Of course, the first to go will be C58, the 4
> MFD electrolytic in the AF Amplifier. What has been the Group's
> collective experience getting one of these receivers back on the air?
> 73, Matt, W2NS 

Hmmm....perhaps it is time I checked mine. I have two. I have used my first one quite a lot, 
and have really enjoyed it. I never tested it before I first fired it up, but, perhaps, now, your 
question makes me want to check both of mine a bit closer. 

I'll do that asap and will report back here.

BTW, and FYI, I had bought a spare, almost impossible to find, 1L6 ($50) for "just in case", 
but finally swapped the 1L6 for a solid-state version which a very competent builder sells on 
eBay foir users of the Zenth Transoceanics. The maker builds them into a glass tube with 
pins which allows one to simply plug it into the 1L6 socket. 

No changes, whatever, to the circuit required.

I am amazed at how much better the receiver works with that in place of the 1L6.

The receiver is quierter, appears more sensitive, and (here is the big difference), the receiver 
no longer over-loads or blocks on strong signals.

I very highly recommend that sub for anyone who needs to use a 1L6 in anything.

Another big advantage to this is that all one has to do to revert the receiver to stock is 
un-plug the solid-state "tube" and plug a 1L6 back into the socket.

Ken W7EKB

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