[600MRG] RBA's and RAK's and RAL's

[Kenneth G. Gordon]

On 3 Nov 2014 at 3:15, NMF wrote:

> One thing I tried on a pristine RAK one owner was to just disconnect the 
> power supply and put it aside...

When the ballast tube is turned on, that power supply uses 300 watts, mostly 
in heat. A much smaller, more modern supply, will work just as well.

> Next was to solder MPF102s to each tube socket base along with 
> appropriate R and C coupling, add 9V battery and it will run for at 
> least 2 weeks if left on...

Hey! That's a darned good idea!

> Keep the tube in in order to not have to 'retune' the selective TRF 
> filters...

Good!

> Adding 2 BNC connectors also made for double use as the TRF stages as an 
> amplified 'pre-selector', man that rig is tight, very high quality!!!

Boy! You can say that again! The RAK really and truly is "single signal" on 
MF/VLF. The other side of zero beat simply isn't there. All the RF coils are 
toroids wound with Litz wire. Their "Q" must be incredibly high for such an 
ancient design.

As far as my experience is concerned, the RAK is the finest TRF VLF 
receiver of the period. The only VLF receiver that is any better is the huge, 
hulking RBA.

The RAK is far, far more stable than any others I have used, including the 
later National RBL which drifts back and forth very noticeably.

The RAK just "sits there" for hours.

I consider its HF brother, the RAL, to be the finest HF TRF receiver ever 
built. I used one for something like 12 years as my only station receiver and 
just loved it. 

I still have several of each receiver here, plus two RBAs, and several RBLs.

Gotta get rid of the excess soon, though. My sweet wife is getting 
concerned...

Ken W7EKB