[ARC5] GRC-109 or RR-2B

[Clare Owens]

Hi Ken,

Do you mean this seller's 1L6 replacements?  Ebay item 121251195330.

Thanks,

Clare


On Wed, Jan 8, 2014 at 7:19 PM, Kenneth G. Gordon
<kgordon2006 at frontier.com>wrote:

> On 9 Jan 2014 at 10:12, Leslie Smith wrote:
>
> >   G'day list readers.
> >   Can any-one on this list  comment on the general capability of the
> >   GRC-109, 3 band receiver, covering 3-6, 6-12 and 12-24 MHz.
> >   This set is also known as RR-2B - a 6 "tube" superhet.  I have a copy
> >   of the TM.
>
> I have an AN/GRC-109 which I use on the air regularly. Over a period
> of several years, I worked 35 countries with it on 40 meters, crystal
> controlled, and I was using a low end-fed wire antenna too.
>
> >   It uses the miniature "toobs", including the hard-to-get 1L6.
>
> I found a fellow who makes a solid-state replacement for the 1L6
> which works much better than even a new 1L6 does. Although I have at
> least two NIB 1L6s, I MUCH perfer the SS replacement. The fellow
> builds them into minuature tubes so they simply plug in to the 1L6
> socket. For one thing, the 1L6 "pulls" frequency on strong signals
> and when keying the transmitter. The SS version doesn't do any of
> this. It is rock solid.
>
> >   The selectivity appears to be broad (9 kHz at 6 dB "down").
>
> Correct. Although I "sweep aligned" mine, it really is wide.
>
> >   (Seems broad for a set with 2 I.F.'s at 455 kHz)
>
> That can probably be improved by working on the IF transformers.
>
> >  Sensitivity is quoted at 5uV.
>
> Although I have not tested mine, I think the actually sensitivity is
> better than that. I have no problem copying any one I need to. I DO
> use an external audio amp though: one of those small 9 V battery
> powered Radio Shack jobs. I also use a "beam filter" with mine, which
> makes a big difference.
>
> >   I have not been able to find a spec relating to stability.
>
> In my opinion, the receiver is quite stable. Also, it is capable of
> being crystal controlled: there is a crystal socket with a built-in
> bypass switch mounted on the front panel.
>
> However, due to the way the T-784 (or its TT equivalient) does "QSK"
> the receiver overloads easily. It has no AGC. Furthermore, again due
> to the QSK method, there is TERRIBLE "suck out" if you use the RX and
> TX on the same frequency. The transmitter's tuned circuits reduce the
> receiver input by 30db. In fact, the manual tells the operator to use
> a separate antenna for the RX if he must operate with RX and TX on
> the same frequency.
>
> Normally, when those rigs were used by the Special Forces in 'Nam,
> the receivers were on a much different frequency from the
> transmitter.
>
> Ken W7EKB
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