[Hammarlund] Favorite Hammarlund Radio

Sun Dec 11 20:31:02 EST 2011

----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "Hammarlund Radios" <hammarlund at mailman.qth.net>
Sent: Sunday, December 11, 2011 12:54 PM
Subject: Re: [Hammarlund] Favorite Hammarlund Radio

> On 11 Dec 2011 at 9:17, Carl wrote:
>
>> ** But it had fairly steep IF skirts plus the filter. I find the RBB
>> enjoyable on 80CW even on a crowded band and the RBC is fine on the
>> higher bands.
>
> I found my RBB to be a very enjoyable and useful receiver in its
> range. I was not as impressed by my RBC. However, that may be because
> it wasn't up to snuff.

While they resist the ravages of time better than most they do need a bit of 
TLC if you want to enjoy them as built.

>
> I STILL wish I had the pair in my shack. (sniff...) :-(
>
>> ** Look at the front ends again Ken; circuit design and the tubes
>> used. The RCA's used the latest and quietest while the SP's used the
>> noisest and most obsolete they could find.
>
> Well, I don't know that that is quite true: at the time the SPs were
> designed, the tube and circuits used were the most common. But you
> are certainly correct in your assessment of those circuits and tubes:
> they were NOT the best by any means.

It is absolutely true. The SP-10 used the older big pin glass tubes and the 
1937 SP-100 used 1935 released metal octal tubes in the front end and in the 
audio; old glass elsewhere. The late 1939 SP-200 went to all octal but didnt 
upgrade with improved versions. The 6L7 in particular is one of the noisest 
tubes ever developed and is even worse than the 6K8. The 6K7 only has a Gm 
of 1700, similar to the sorry 6S7 in the HQ-120.
The 6SA7 was out in late 38 and the 6AB7 and 6SK7 in early 39. Preferred 
OEM's had samples long before that. Even Hallicrafters had up to date tubes 
in the 1939 SX-25. Since most SP-100's didnt go beyond 20mc it was a 
blessing in disguise.
National was another who fought tube advancement tooth and nail but at least 
they had minimal loss with the plug in coils and sliding catacomb.

Dont get me wrong as I like my SP-100, 200 and 400 type SP's but even Henry 
Ford went with hydraulic brakes in 1939 (-;

>
>> While most anything will
>> work well where the antenna noise predominates the SP's wisely stopped
>> at 20mc in most models. My SP-400 is deef on 15/10M considering its
>> other qualities and its just a rebadged SP-200. The RBx's are almost
>> too sharp for AM quality and were mainly used for CW and RTTY. AM was
>> for short haul such as entering port.
>
> Yes. As I said, I found my RBB to be just about perfect for CW and
> RTTY at the time I was using them, which was back in the 1960s.
>
>> ** Having spent several years aboard ships with the RBx's and the
>> RAK/RAL as emergency backups I can say without a doubt the RBx's were
>> completely immune to overload. Dont forget that the CW nets were full
>> break-in with seperate RX/TX antennas only seperated by a short
>> distance.
>
> Like **I** did it. :-)
>
> BTW, in my talking about the RBB/RBC, I had momentarily forgotten
> that you were a Navy Chief and spent years in the Navy using those
> receivers, so you know more about them than I ever could.

I left active duty as ET2 and made Chief and WO in the Reserves. My yearly 2 
week vacation was on ships with more modern equipment or Tender duty 
spelling another on leave; or I flew a desk on shore. It was tender duty 
where I really developed my hate for SRR's to perfection. Ive heard more 
than one story at the time of a few getting tossed over the side. By E8/E-9 
Chief time I was mostly involved with Crypto and instructing at the monthly 
weekend duties. As WO there are things I still cant talk about but suffice 
it to say I was called out of retirement (1987) for GW1 but cooled my heels 
in Rota, Spain as things were over quick.

>
>> ** The audio limiter/AGC in the RAK/RAL is equally effective. They are
>> arguably the best regens ever built....another RCA great.
>
> I consider the RAL quite simply the finest HF TRF receiver ever
> built, bar none. I used one for something like 12 years as my main
> station receiver and absolutely loved it. I have two today.
>
> When I read that stupid statement in the CQ magazines Surplus
> Conversion Manual about it being a "hopeless antique" I got highly
> incensed. Obviously whoever wrote that never used one. :-(
>

It required a bit of smarts to get the most out of it; I had enough idle 
time aboard ship to get really good with it since the ET shack and Emergency 
Radio were in the same compartment. I even did some HB and kits there. That 
oiler was always on the go and we spent no more than 28-30 days a year in 
home port, Newport, RI. The reefer was 6 weeks on  and 2 off back and forth 
to the Med. Our liberty port was Palma de Majorca (-;

>> Too bad they
>> blew it with the POS SRR series.
>
> Well, the SRR series had some pretty good points, and some innovative
> ideas. However, after working on those for a considerable period of
> time, it became painfully obvious to me in very short order that RCA
> must have had some new and inexperienced design-engineers working on
> that project.
>
> For one thing, they had all the tubes in that thing with the screens
> operating at the exact same voltage as the plates! Talk about heat
> and wasted power and noise! Geeze!
>
> I fixed quite a number of the SRR-11/12 and 13 one of my early
> employers was using by removing every module, and installing a 56K
> resistor in the screen feeds, bypassed where necessary.
>
> That simple process reduced the heat produced by at least one
> magnitude, and thereby increased their reliability. It ALSO
> dramatically reduced the internally generated noise!
>
> After doing that, I was impressed, overall, by the receiver.
>
> One thing I did like about the SRR was that projection dial readout
> system: as far as I am concerned, it is the only analog dial readout
> that had enough accuracy. It ALMOST equaled a digital readout. The
> "dial scale" was something like 12 feet long.
>
> And the SRR had a real product detector too. I don't know of any
> other receiver of the period which did.
>
> Lastly, I really, really like those subminature tubes used in it.
> Those things are amazingly reliable....when they aren't being cooked
> to death by some stupid kid designer right out of school.
>
> A couple of other things I didn't like about the SRR were the cranks
> in the bandswitching mechanism, especially the early ones, which were
> always breaking, and secondly, the damned coils would go bad on you
> and had to be rewound. But even those two things, if one was careful,
> didn't happen very often...and today, both can be fairly easily
> fixed.
>
> I have several examples of the SRR-11/11A and the SRR-13/13A in the
> queue to be restored, but I have only one SRR-12.
>
> Ken W7EKB
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