[National] Re: [Boatanchors] National HRO-500

[peter markavage]

Carl:
Why no noise limiter or noise blanker in the 500? And, why are the switch
contacts such a pain to keep the PLL  locked in if you let it sit in one
bandswitch position for long periods of time and then try switching to a
different position. I've heard such frustration from some 500 owners that
they actually hard wired the PLL contacts on the switch for the main
bandswitch position that they use. Of course, a very severe ultimate fix.

An FET front end would probably add life to the receiver and "glow" to
the user.

Also the lamp behind the red lens for the dial indicator (the pointer)
has gone out. I can't remember, since I don't have the receiver or docs
in front of me; do you have to pull the front panel in order to get at
the lamp?

Pete, wa2cwa

On Fri, 30 Dec 2005 15:44:20 -0500 "km1h" <km1h at jeremy.mv.com> writes:
> I have a wee bit of experience with that unit.
> 
> For its day it was well ahead of most anything else on the market. 
> Its 
> primary fault is (as compared to some of todays rigs as well as the 
> R390A) 
> strong signal handling. I keep planning to convert the front end 
> over to 
> FET's but it never reaches a priority around this zoo.
> 
> Carl
> KM1H
> National Radio 1963-69
> Service Tech, Service Manager and some other hats.
> 
> 
> 
> ----- Original Message ----- 
> From: "peter markavage" <manualman at juno.com>
> To: <boatanchors at mailman.qth.net>
> Cc: <national at mailman.qth.net>
> Sent: Friday, December 30, 2005 12:16 PM
> Subject: [National] Re: [Boatanchors] National HRO-500
> 
> 
> > You can do a search on the boatanchor and National archives to 
> review
> > past discussions on the HRO-500. Most of the time the lack of sync 
> lockup
> > can be traced to gold contamination on the bandswitch contacts. 
> Cleaning
> > carefully with deoxit can help alleviate the problem. Also 
> remember that
> > the bandswitch also turns a switch on the top of the chassis 
> through a
> > pulley/cord. Proper physical alignment is a must. I generally rock 
> my
> > bandswitch through all the positions at least once a week even 
> when I'm
> > not using the receiver. The contact switch wiping helps keep the 
> switch
> > contacts clean. Strong front-end overload has always been a 
> problem with
> > this receiver. SSB distortion has also been reported on a number 
> of these
> > receivers. ER magazine also ran several articles on this receiver
> > incuding some mods.
> >
> > Probably one of the more highly over-rated receivers as far as 
> over-all
> > performance.
> >
> > Pete, wa2cwa
> >
> > On Fri, 30 Dec 2005 09:53:54 -0500 flood at Krohne.com writes:
> >> Greetings,
> >>
> >> First of all Happy New year!
> >>
> >> A HRO-500 followed me home yesterday.  Aside from a dent in the
> >> lower back
> >> corner the unit is very good cosmetically.  It powers up but the
> >> synth.
> >> only locks up at 3.5 and 29.5 MHz.  I have the manual and am
> >> starting to
> >> study it but was wondering who the resident HRO-500 experts are.
> >> Boy this
> >> is a lot different than anything I've ever worked on before but 
> at
> >> least I
> >> can still see the parts without a microscope and I don't have to
> >> worry
> >> about sticking my finger on several hundred volts of B+.  Is 
> there a
> >>
> >> better list for help with this beast?   It is after all 
> solid-state
> >> and a
> >> lot lighter than my other toys.
> >>
> >> Also, is there anyone left here in the northeast who repairs 
> these
> >> in case
> >> I get hopelessly lost?
> >>
> >> John Flood KB1FQG
> >> TASC Department
> >> KROHNE, Inc
> >> 7 Dearborn Rd.
> >> Peabody, MA   01960
> >> Tel.:  978-535-6060 / 800-356-9464
> >> Fax:   978-535-8180