[ARC5] Regeneration, and the RU, among others.

[Kenneth G. Gordon]

On 16 Sep 2010 at 23:35, Leslie Smith wrote:

> Hello Ken,
> 
> Below you wrote that the German and US TRF receivers didn't suffer
> from "touchy" operation/regeneration.  Do you mean that these sets
> were "nice" to use, despite requiring double-handed operation?  Or (in
> contrast) do you mean that the design was sufficiently good that these
> sets didn't require adjustment across the band?  (I suspect the
> former, but will look at the design very closely if the latter!)

By all means, the latter!!! 

I have used several U.S. military TRF receivers, mostly those for 
VLF, but my favorite, the RAL for HF. There is absolutely 
NOTHING requiring "two-handed" operation. Even the regen 
control has an auxillary pot attached to the rear of the main tuning 
dial that automatically compensates for the change in regen 
setting across a band. 

You simply set it and forget it.

The German versions are equally well designed and built, 
although I have never had an opportunity to use one.

I HAVE read of their use on various Eurpoean web sites, and they 
are universally praised.

The only drawback to the TRF design is that obtaining what we 
would call "good" RF selectivity today is difficult since ALL that 
selectivity is only available in the RF stages, and this effect get 
worse the higher the frequency. This is why at least two RF 
stages are used in most of them.

Nonetheless, in the RAK for instance, the selectivity is truly 
single-signal: there simply is no other side of zero beat, period.

Both the RAK and the RAL use Litz wire honeycomb basket 
wound toroid coils of extremely high "Q".

On HF, with the RAL, the selectivity is quite adequate, and the 
very very fancy audio filter makes a huge difference.

I have been told that some of the old U.S. Navy radio ops actually 
preferred the RAK/RAL over the RBB/RBC on certain ships since 
the earlier receiver was not as prone to overload by nearby 
transmitters.

You can see both an RAK and an RAL (among others) here:

http://www.w7ekb.com/glowbugs/BA/

Also, there was an article in a recent issue of ER concerning the 
RU, which is also a TRF. The author found it to be a really 
excellent receiver. It, also, does NOT require "two handed" 
operation.

He was very surprised at the stability and sensitivity, which far 
exceeded what he expected to find.

His conclusion was that the RU was, essentially, a really superb 
Direct Conversion receiver.

Ken W7EKB