[Boatanchors] USS Midway notes

[Richard Knoppow]

----- Original Message ----- 
From: <WA5CAB at cs.com>
To: <greenkeys at mailman.qth.net>;
<boatanchors at mailman.qth.net>
Sent: Tuesday, March 01, 2011 1:31 PM
Subject: Re: [Boatanchors] USS Midway notes


> Actually, if it had an RBG-2 nameplate on it, it's part of
> an RBG-2, not an
> HQ-anything.  According to NAVSHIPS 900,004, none of the
> RBG receivers had
> a crystal filter.  RBG-1 had a CHC-46163 receiver with 25
> cps power supply.
> RBG and RBG-2 had a CHC-46140 receiver and were 60 cps.
> Otherwise the only
> differences between the three were the two nameplates and
> the contract
> numbers.  Besides the receiver, the rest of what made up
> an RBG-(*) was a shock
> mount, a loudspeaker, a case of spare parts, and two
> manuals.
>
> I'm pretty sure that Midway never had a RAK-4 aboard
> (while in commission).
> She would have commissioned with RBA/B/C, then probably
> got R-390A's, and
> then R-1051's.  I served on another carrier commissioned a
> few months after
> the Midway and that was the sequence aboard her.  Late
> WW-II ships didn't
> generally have the misfortune of getting the AN/SRR-11, 12
> & 13.  :-)
>
> In a message dated 3/1/2011 2:44:24 PM Central Standard
> Time,
> rinkies at att.net writes:
>> I believe the Hammarlund is the HQ120, or 120X (the "X"
>> had the crystal
>> filter in it).  One way to tell is to look at the tubes;
>> the 129 has all
>> octal, and the 120 has tubes with grid and/or plate caps.
>>
>> I have manuals for both that I can copy if you like, and
>> live in the San
>> Diego area.
>>
>> Ron K2RP
     The CHC-45140 is shown at:
http://www.radiomuseum.org/r/hammarl_mf_rbg_2_chc_46140.html
     It pretty definitely has the crystal filter in it.
However, if the tube line-up given is correct it is not an
HQ-120-X but a modified version with single-ended octal
tubes and somewhat different tubes than were used in the
later HQ-129-X (6SK7 where the HQ-129-X had 6SS7).
     There are a couple of clear photos of the front panel
at:
http://www.ohio.edu/people/postr/bapix/RBG2.htm
     Again showing the crystal filter.
     While Hammarlund evidently made a version of the HQ-120
without the filter I have never see one. The Hammarlund
crystal filter was patented by them and was first introduced
in the HQ-120-X, being made available for the Super-Pro
after that. The Hammarlund xtal filter was excellent
overcoming the defects of the original Lamb circuit as used
by National and Hallicrafters (and others). This is the same
circuit later used by Collins, TMC, etc in their receivers.
     RE 25hz power. The military version of the Super-Pro
was avaiable with a 25hz supply. The difference is in the
power transformer and chokes, they will run fine on 60hz
where a 60hz transformer will overheat badly on 25hz power.
25hz was mostly used for large industrial motors of the sort
used on some electric railways and manuacturing plants. In a
few places home current was also 25hz. I remember this from
visiting the Canadian side of Niagra Falls with my parents,
perhaps in the late 1940's. The local current was 25hz
making lights flicker quite noticably.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com

--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com