[ARC5] 80 KHZ IF

[tbs50a at aol.com]

 >since its own IF was 455kc.
To be fussy the early HRO's were 456kc, the ones with the big round crystal on top of the filter unit. 
The later sets about 1944 or so moved down a kc and the crystal was mounted inside the filter unit. 
I've read that the reason for this is that the top mounted ones the crystal element it self when unpluggedcould make a rattling noise. Owners thought this was a problem and take the crystal unit apart andmonkey with it. National thought that wasn't such a great idea so it got to the inside where pryingfingers couldn't get at it. 

Terry N3GTE 

 
 
 
-----Original Message-----
From: Kenneth G. Gordon <kgordon2006 at frontier.com>
To: ARC-5 List <arc5 at mailman.qth.net>; Roy Morgan <k1lky68 at gmail.com>; J Mcvey <ac2eu at yahoo.com>
Sent: Sun, Feb 14, 2021 4:22 pm
Subject: Re: [ARC5] 80 KHZ IF

On 14 Feb 2021 at 19:59, J Mcvey via ARC5 wrote:

> I thought the later HRO series had 176KHZ IFs,

No. That would have only been the National's Navy RAS series...and it was 175 kc, not 176.

> but I found a reference to 1939 
> Navy RAS National with a 176Khz IF
> It was fashioned after the HRO junior?

Well, kind of concurrently with the Jr. The 175 kc IF was chosen because the RAS had to 
cover the same frequencies as the IF of most radios at the time. It covered MF (190 kc) and 
up through 30 mc. The HRO had to skip the range around 455 kc since its own IF was 455 
kc.

Ken W7EKB
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