[TenTec] Paragon problem

Sun Jul 13 16:15:41 EDT 2014

As to any reed relays, K1 and K2 on the Low Pass filter board toggle between 
being closed or open alternately by the T and R voltages.  If for some 
reason these relays are both closed at the same time, RF from the 
transmitter would be fed into the High Pass filter board for the receiver. 
If the K2 relay is stuck closed, then the same issue of RF from the 
transmitter is fed to the Band Pass filter board.

Thus on receive, K1 is open and K2 is energized by the R voltage, connecting 
the Low Pass filter to the receiver antenna at connector 13.  From connector 
13 the receive signal is passed through the receive High Pass filter board 
by way of the rear RX/TRX switch.  The TX/TRX switch on the rear has been 
noted to cause issues.  I just replaced one of these switches a Corsair II 
as it was showing a 3 to 6 S unit signal loss on receive.

In as much as diodes D1 - D8 were open I more suspect a nearby lightning 
strike took out these.  I find this is quite a common occurance.

73
Bob, K4TAX

----- Original Message ----- 
From: "Bob McGraw - K4TAX" <RMcGraw at Blomand.net>
To: "Walt K8CV" <waltk8cv at wowway.com>; "Discussion of Ten-Tec Equipment" 
<tentec at contesting.com>
Sent: Sunday, July 13, 2014 1:34 PM
Subject: Re: [TenTec] Paragon problem

> Since there are no reed relays, or relays of any type, one would do better 
> to do a DC voltage check of each filter section for each band.  This can 
> be done with the RX HP Filter removed but connected to the radio via the 
> ribbon connector. This way the radio can switch bands and one can measure 
> to confirm switching is taking place by measuring the voltage across each 
> of the 16 diodes.  There's 16 of them as indicated on the schematic.
>
> Out of the radio and no power applied, each diode can be accurately 
> checked for forward and reverse resistance with an ohm meter with a 
> suitable diode test feature.  Or use one of the old fashion VOM type 
> meters.
>
> One other note, be mindful if the issue exists on all bands or just one or 
> two bands.  The switching voltage can be observed on connectors #16 and 
> #14.
>
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message ----- 
> From: "Walt K8CV" <waltk8cv at wowway.com>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Sent: Sunday, July 13, 2014 7:41 AM
> Subject: Re: [TenTec] Paragon problem
>
>
>> Have you changed the reed relays or talked to TenTec about them? A stuck 
>> / pitted transmit reed will suck off the receive.
>>
>>
>>
>> Walt K8CV
>> -----Original Message----- 
>> From: Vic Klein
>> Sent: Sunday, July 13, 2014 6:34 AM
>> To: tentec at contesting.com
>> Subject: Re: [TenTec] Paragon problem
>>
>> Thanks for the suggestions. A few days of sleuthing and talking to Garry 
>> at
>> Ten Tec led me to discover that all the input (D1-D8) switching diodes on
>> the Hi-Pass filter board (81330) were "open". Garry said In4148's could 
>> be
>> substituted, which I did, and now all the sections seem to test OK and
>> switch appropriately...but the same symptoms remain: all functions seem
>> normal, but sensitivity is off by around 4 S-units. None of the RF chokes
>> seem to be open, and bypassing the Lo-pass FX board by selecting the
>> external receive antenna makes no difference. I am looking at the 1st 
>> Mixer
>> now, although I do get the appropriate 20dB reduction when switching in 
>> the
>> attenuator, which shuts off the RF stage, so I am still befuddled.
>>
>> One anomally I see is the the voltages on the band switching diodes seems 
>> a
>> bit low. I would have expected a lower voltage at D1 as it has more
>> resistance in the path, but the reverse is true and it reads about 9.4v 
>> as
>> opposed to the other 7 Hi-pass sections at about 7.25v when selected. 
>> That
>> still seems plenty to bias the diodes and pull in the low-pass relays, 
>> but
>> curious.
>>
>> =Vic=
>> WA4THR
>> ____________________________________________________________
>> To: Discussion of Ten-Tec Equipment <tentec at contesting.com>
>> Subject: Re: [TenTec] Paragon problem
>> From: Wade Staggs <tvman1954 at gmail.com>
>> Reply-to: Discussion of Ten-Tec Equipment <tentec at contesting.com>
>> Date: Wed, 9 Jul 2014 17:39:05 -0500
>> List-post: <tentec at contesting.com">mailto:tentec at contesting.com>
>>
>> *Far from being an Expert myself, The first place I would look would be 
>> the
>> RX High Pass Filter Board ( 81330 ) At the Antenna Input to the High Pass
>> Filter Board, there are two LC Coils and a Diode ... Any of which could 
>> be
>> Shorted or open in the case of the LC Coils. You should be able to inject
>> signal or an antenna input on each side of the High pass Filter Board. I
>> would use a Clip Lead and touch my Antenna to the output connection from
>> the board and see what happens. The High Pass Filter board uses Switching
>> Diodes to select the correct Filter for each Band. I am believing that 
>> like
>> Ivory Soap, 99 44/100s percent sure that the problem is somewhere on the
>> High Pass Filter Board.*
>> *                                     73 and May God Bless from 
>> Wade/KJ4WS*
>>
>>
>> On Wed, Jul 9, 2014 at 5:20 PM, K8JHR <jrichards at k8jhr.com> wrote:
>>
>>> Hi Vic -- I am far from expert on this, but I wonder if you can locate
>>> ANOTHER protective diode in the receiver circuit.  I once killed my Omni
>>> VII receiver by hot-switching an "active" receive only antenna - the 
>>> power
>>> connector arced to case ground of a bias-tee injector as I plugged it 
>>> in,
>>> and that fritzed the receiver.  Gary at TenTec service called me to
>> explain
>>> it before he fixed it, and I believe he said there were multiple diodes 
>>> to
>>> protect the rig in such cases.
>>>
>>> So... perhaps you have more than one diode or fuse or other prophylactic
>>> device to check?
>>>
>>> -----------------------------K8JHr ------------------
>>
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>
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