[AMRadio] HRO-50

jeremy-ca km1h at jeremy.mv.com
Mon Nov 26 17:54:41 EST 2007

Finally, some one actually read the manual!

The alignment is actually quite simple once youve been thru it once.

The way we determined which way to move that wire was to insert a plastic 
rod with a piece of aluminum glued on one end and powdered iron on the 
other. Aluminum decreases the inductance and iron increases it.

National Radio 1963-69
Service Tech, Service Mgr
Member of NCL-2000 Design Team
----- Original Message ----- 
From: "Larry Will" <lhwill at verizon.net>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Monday, November 26, 2007 5:38 PM
Subject: Re: [AMRadio] HRO-50

> Mike,
> My book indicates, like many National receivers, on D band a single loop 
> of wire inside of the coil is bent to add/subtract inductance.  I just 
> looked at my RF input coil (opened it up) and there is the wire.
> The wire is accessible through the left rear hole, looking from the top of 
> the assembly (the side with the contacts).
> Se page 19 in the HRO50-1 National manual for all the coils.
> I have seen some cases on some receivers (not an HRO-50) where the range 
> may not be sufficient.
> Larry
> W3LW
> 11111
> At 04:03 PM 11/26/2007, you wrote:
>>What a pain in the scrote. The manual says to adjust the coils for the low
>>end of the band, (in this case, I'm using coil set D 1.8-4.0M GC 3,5-4.0 
>>and there aren't any adj. available. I looked in the in each coil set and 
>>can see the coil but it looks as though it was designed not to be adj. and
>>I'm hesitant about attempting to adj. them. The only one that has an
>>adjustment for GC is D-4. It worked well on 160 but it was damn near deaf 
>>75M. I wanted to make it back to standard but its a real tough go. I 
>>have left well enough alone. Well, in for a penny, in for a pound.
>>----- Original Message -----
>>From: Jim Wilhite
>>To: Discussion of AM Radio in the Amateur Service
>>Sent: Monday, November 26, 2007 3:22 PM
>>Subject: Re: [AMRadio] HRO-50
>>Fun isn't it Mike.  That is the way.  If there is an easier way, I would
>>like to see it.

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