[TenTec] Filters - for the Omni VI v.3

[Dr. Gerald N. Johnson]

On 9/2/2010 8:04 PM, Chris Wagner wrote:
> Jerry,
> thank you for making valid points. As a beginner and future rag-chewer
> rather than contester, the 250 Hz filters are out. To put a 1.8 khz filter
> in the stage 1 slot - would that work?

The 1.8 would work for CW but would be of marginal benefit. I'd not 
consider it worth the cost.
>
> The TRX is still with the seller. No Ten Tec transceiver is type approve for
> Thailand where I am these days. And having 50 ohm coax cable of 3 ft or more
> length carries already a jail term of 5 years. But then, I would guess they
> would deport such an offender after a few weeks without the option. And type
> approval would cost 25,000 Baht or>$ 800 as the regulator makes no
> difference between commercial and amateur requests :X

Ham rigs work just fine with 75 ohm coax. The SWR of many antennas is 
poorer than that mismatch and the RG-6 of TV will stand transmitting 
just fine. RG-59 will stand 100 watts too. Both would be better with a 
copper braid shield than aluminum shield.
>
> SSB is of less interest to me. But would it still be usable with a 1.8 khz
> filter?

1.8 is narrow for SSB, but SSB can be copied through it, sometimes to 
advantage in heavy QRM. I used a Collins 2.1 for many years and that's 
the bandwidth I tend to prefer. You can achieve the 1.8 or narrower 
selectivity with using the Omni's bandpass tuning. With the same filter 
bandwidth (stock situation) in both IF frequencies, and the bandpass 
tuning knob centered you get the full bandwidth. Turning the bandpass 
tuning knob slides the filter pass bands resulting in a narrower working 
passband that is adjustable. Tentecs do that better than any other 
radio. Turning the bandpass tuning knob one direction raises the LF end 
of the passband, the other way lowers the upper end of that pass band 
and which is which depends on the sideband and the band.

The pass band tuning has a different effect when the wide filter is in 
the 9 MHz slot and there's a CW filter in the 6.3 IF slot. Then bandpass 
tuning moves the narrow CW filter across the SSB filter changing the 
center frequency of the CW filter without changing the bandwidth except 
at the edges of the SSB filter passband.

With either filter combination you can achieve a very narrow CW filter 
with the bandpass tuning and stock filters.

When I bought my Corsair II several years ago I also bought a 500 Hz CW 
filter for the 6.3 IF from a different source. I ran the rig more than 
half a year before I bothered plugging in that CW filter because I 
achieved very adequate selectivity with the stock SSB filters and using 
passband tuning.
>
> Wednesdays, I had 2 CW QSOs after years of inactivity. Botched them horribly
> and it was reported on the DX cluster. Hadn't thought of that - but better
> clean up my act - and fast!

Living in countries with a small ham population, you will be in demand 
for short QSOs and QSL cards.
>
> This is the item:
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140445505043&ssPageName=STRK:MEWNX:IT
>
> Thanks also to two kind OM who gave advice and support off the list. Ham
> spirit is alive and i look forward to bringing the Omni on the air.
>
> 73 de Chris HS0ZFE  KF6VCI  MI1ESG
> ______________________________________________________________
>
73, Jerry, K0CQ