[TenTec] Scout has vy low Pwr out on some bands

[Mike Bryce]

Rick

Check the barrel connectors. 

They route rf in and out of the module. 

The prongs get loose, causing the issues your having. 

Mike wb8vge 

Sent from my iPhone

> On Jul 15, 2014, at 11:48 AM, "Rick - DJ0IP / NJ0IP" <Rick at DJ0IP.de> wrote:
> 
> Tnx for your answer, Wes.
> 
> I meant to say "LOW PASS FILTER" (for the final amp), not BPF.
> The BPF is only used for the RX and it is working OK.
> 
> IMO it must be this LPF circuit, and it has just 2 coils and 3 caps.
> But of course you can't really get at it to see or measure anything.
> (Murphy)
> 
> I don't agree with your logic (but I am not sure).
> Normally the input to the bridge (from the LPF) would be a nominal 50 Ohms
> and on the dummy as it is, also 50 Ohms.
> If either side changes, it causes an imbalance and shows high SWR.
> 
> I think I'm going to have to get out a BIG soldering iron and try to remove
> the metal shielding around the circuit so that I can pull and measure the 5
> components in the LPF.  I hope I don't burn up the board.
> 
> But first I'm going to try bypassing the LPF entirely and just running the
> power straight to the dummy.
> If it's 50 Ohms, then I will know the problem is the LPF.
> It's easy in theory but tough to get at inside the radio.
> 
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
> 
> 
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Wes Attaway
> (N5WA)
> Sent: Tuesday, July 15, 2014 5:36 PM
> To: 'Discussion of Ten-Tec Equipment'
> Subject: Re: [TenTec] Scout has vy low Pwr out on some bands
> 
> I don't know anything about the radio, but it seems like if the BPF is
> causing an SWR problem then the SWR would have to be measured at some point
> between the TX output and the BPF (ahead of the BPF rather than after it).
> Is this the way the schematic shows it?
> 
> I guess you could connect an external SWR meter to confirm this idea.  An
> external SWR meter should not be affected by the BPF. 
> 
> ----------------- Wes Attaway (N5WA) -------------------
> 1138 Waters Edge Circle, Shreveport, LA 71106 
>                  --- 318-393-3289 (Cell) ---
>        Computer Consulting and Forensics
> -------------- EnCase Certified Examiner --------------- 
> 
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Rick -
> DJ0IP / NJ0IP
> Sent: Tuesday, July 15, 2014 9:39 AM
> To: 'Discussion of Ten-Tec Equipment'
> Subject: [TenTec] Scout has vy low Pwr out on some bands
> 
> I received my new (used) Scout yesterday.
> After a long search, I finally found a power plug and 9A Airpax circuit
> breaker in my junkbox.
> I built a cable with the breaker and am powering it from a 963.
> 
> The Scout came with band modules for all bands except 17 & 12.
> There is no NB.
> The RX seems to work fine on all bands.
> 
> On two of the bands (160 and 40m), I get very low output power - about 8w
> and 2w.
> On all other bands it easily brings 50+ watts on my cheap watt meter (10%
> accuracy).
> 
> I changed modules quite a lot, making tests first on a dummy and then on an
> antenna.
> At one point 40m suddenly worked, with full output power.
> I made several 40m SSB QSOs with it.
> 
> Later when I plugged the 40m band module back in, the power was again 2w.
> When I get the 2w, the SWR also shoots up.  When it was working properly,
> the SWR was good.
> 
> I have studied the diagram of the band modules.
> Since the RX seems to work properly, I assume the oscillator and mixer of
> these modules are working OK, as well as the HPF on the 160m module and the
> LPF on the 40m module.
> 
> The only thing left is the actual Bandpass Filter for the TX.  It is
> encapsulated in shielding and I can't really get at it.  
> I have re-soldered all connections on the bottom of the PC board but no
> change.  Still 2w.
> 
> I can't see how it would be anything but the BPF - or am I missing
> something.
> 
> Any tips?
> 
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
> 
> 
> 
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