[Boatanchors] Update on the National NC-140 that's on the bench

[Bill Henderson]

I've used a rosin block in the past with success but eventually the cord
will have to be restrung.

 - Bill H. / va3hwa



<https://mailtrack.io/> Sent with Mailtrack
<https://chrome.google.com/webstore/detail/mailtrack-for-gmail-inbox/ndnaehgpjlnokgebbaldlmgkapkpjkkb?utm_source=gmail&utm_medium=signature&utm_campaign=signaturevirality>

On Tue, Oct 24, 2017 at 9:18 PM, Phil <ko6bb1 at gmail.com> wrote:

> OK, today is the first chance I've had to fire up the NC-140 on the variac
> and run some preliminary tests (had a Kenwood Dual Bander on the bench til
> today).
>
> The owner reported that it needs alignment, and possibly some audio work
> as the audio doesn't sound right.  Here's what I found so far.
>
> 1. Sensitivity seems way down, even on the AM BC band.  Tuning bandwidth
> seems extremely broad on BCB stations (didn't test SW yet).
>
> 2. Audio weak and heavily distorted.
>
> 3. Slipping main tuning dial cord.
>
> Further testing showed that the audio problem is actually an AGC problem.
> Turned the RF gain control down and suddenly the audio was clear and had
> plenty of volume, and the "S" meter responded to tuning.  I suspect the IF
> strip is clipping until the RF gain is turned down.
>
> Ran out of time today.  Tomorrow I'll pull the chassis and run some
> tests.  Good possibility I'll find a leaky cap.
>
> QUESTION:  I seem to recall that use of a rosin block (for a violin bow)
> is a common fix for slipping dial cords.  Never used one, always restrung
> as needed.  IF the dial cord is otherwise in good condition, should I try
> it, or just order the cord material (assuming the springs aren't stretched)?
>
> If this tube radio work catches on again here, I may eventually have to
> get a tube tester (again) :(  Many years ago when the table I used as a
> bench collapsed under the weight of an R-390A, and nearly put the radio on
> my foot, wifey laid down the law concerning boat anchors!  I gave away the
> really nice Hickock, then later also gave away the smaller "service type"
> tester I bought from a local ham.
>
> --
> 73 From "The Beaconeer's Lair"
> Specializing in DXing NDBs (Longwave Beacons)
> Phil, KO6BB,  http://www.qsl.net/ko6bb/
> KO6BB/B beacon, ~20W on 28.290 MHz, Ringo Vertical
>
> HF/LF RADIOS:
> HOMEBREW:   7 Tube+Rect 1v3 Regen RX for LF (built 2015)
> Icom:       IC-7200 Xceiver, DSP IF & filters (~2015).
> Kenwood:    TS-450SAT Xceiver, cascaded 250/125Hz Inrad filters.
> 10M Beacon: 2 x Realistic HTX-100's on 28.290MHz
> SDR:        Softrock Ensemble II LF (built from a kit 2017).
>
> ACC:   HOMEBREW  LF-MF Pre-Amp, 8Hz Audio Filter.
>        HOMEBREW  4 Port Antenna Multicoupler, Feeds 4 RX's.
>        ANTENNAS: 88 foot Long Ladder-line fed dipole, 35 feet AGL for
> MW/SW.
>           Active Mini-Whip, 36 Feet AGL for LF/MW/SW.
>           37 foot "Low Noise Vertical", 11 feet AGL for LF/MW/SW.
>           Cushcraft AR-10 Ringo Vertical, 14 feet AGL for 10M beacon.
> Merced, Central California, 37, 18, 37N   120, 30, 6W CM97rh
>
>
> ---
> This email has been checked for viruses by AVG.
> http://www.avg.com
>
> ______________________________________________________________
> Boatanchors mailing list
> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Boatanchors at mailman.qth.net
>
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

-- 
CONFIDENTIALITY NOTICE:  The information transmitted in this e-mail is 
intended only for the person to whom it is addressed and may contain 
confidential, personal and/or privileged material.  Any distribution, use 
or copying of this e-mail or the information it contains by anyone other 
than the intended recipient(s) is unauthorized.  If you are not the 
intended recipient and have received this communication in error, please 
notify the sender immediately and delete the message and any attachments 
from your system.